tag:theconversation.com,2011:/ca/topics/quantum-dots-9920/articlesQuantum dots – The Conversation2024-03-28T01:37:12Ztag:theconversation.com,2011:article/2264012024-03-28T01:37:12Z2024-03-28T01:37:12ZQuantum computing just got hotter: 1 degree above absolute zero<figure><img src="https://images.theconversation.com/files/584893/original/file-20240327-26-7h2dj1.JPG?ixlib=rb-1.1.0&rect=11%2C2%2C1985%2C1266&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Diraq</span></span></figcaption></figure><p>For decades, the pursuit of quantum computing has struggled with the need for extremely low temperatures, mere fractions of a degree above absolute zero (0 Kelvin or –273.15°C). That’s because the quantum phenomena that grant quantum computers their unique computational abilities can only be harnessed by isolating them from the warmth of the familiar classical world we inhabit.</p>
<p>A single quantum bit or “qubit”, the equivalent of the binary “zero or one” bit at the heart of classical computing, requires a large refrigeration apparatus to function. However, in many areas where we expect quantum computers to deliver breakthroughs – such as in designing new materials or medicines – we will need large numbers of qubits or even whole quantum computers working in parallel.</p>
<p>Quantum computers that can manage errors and self-correct, essential for reliable computations, are anticipated to be gargantuan in scale. Companies like Google, IBM and PsiQuantum are preparing for a future of entire warehouses filled with cooling systems and consuming vast amounts of power to run a single quantum computer.</p>
<p>But if quantum computers could function at even slightly higher temperatures, they could be much easier to operate – and much more widely available. In new research <a href="https://www.nature.com/articles/s41586-024-07160-2">published in Nature</a>, our team has shown a certain kind of qubit – the spins of individual electrons – can operate at temperatures around 1K, far hotter than earlier examples.</p>
<h2>The cold, hard facts</h2>
<p>Cooling systems become less efficient at lower temperatures. To make it worse, the systems we use today to control the qubits are intertwining messes of wires reminiscent of <a href="https://en.wikipedia.org/wiki/ENIAC">ENIAC</a> and other huge computers of the 1940s. These systems increase heating and create physical bottlenecks to making qubits work together.</p>
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<a href="https://theconversation.com/how-long-before-quantum-computers-can-benefit-society-thats-googles-us-5-million-question-226257">How long before quantum computers can benefit society? That's Google's US$5 million question</a>
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<p>The more qubits we try to cram in, the more difficult the problem becomes. At a certain point the wiring problem becomes insurmountable. </p>
<p>After that, the control systems need to be built into the same chips as the qubits. However, these integrated electronics use even more power – and dissipate more heat – than the big mess of wires. </p>
<h2>A warm turn</h2>
<p>Our new research may offer a way forward. We have demonstrated that a particular kind of qubit – one made with a quantum dot printed with metal electrodes on silicon, using technology much like that used in existing microchip production – can operate at temperatures around 1K.</p>
<p>This is only one degree above absolute zero, so it’s still extremely cold. However, it’s significantly warmer than previously thought possible. This breakthrough could condense the sprawling refrigeration infrastructure into a more manageable, single system. It would drastically reduce operational costs and power consumption.</p>
<p>The necessity for such technological advancements isn’t merely academic. The stakes are high in fields like drug design, where quantum computing promises to revolutionise how we understand and interact with molecular structures.</p>
<p>The research and development expenses in these industries, running into billions of dollars, underscore the potential cost savings and efficiency gains from more accessible quantum computing technologies.</p>
<h2>A slow burn</h2>
<p>“Hotter” qubits offer new possibilities, but they will also introduce new challenges in error correction and control. Higher temperatures may well mean an increase in the rate of measurement errors, which will create further difficulties in keeping the computer functional. </p>
<p>It is still early days in the development of quantum computers. Quantum computers may one day be as ubiquitous as today’s silicon chips, but the path to that future will be filled with technical hurdles. </p>
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<p>Our recent progress in operating qubits at higher temperatures is as a key step towards making the requirements of the system simpler.</p>
<p>It offers hope that quantum computing may break free from the confines of specialised labs into the broader scientific community, industry and commercial data centres.</p><img src="https://counter.theconversation.com/content/226401/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Dzurak works at Diraq. Through Diraq, he receives funding from Australian Research Council (ARC), UNSW Sydney, US Army Research Office (ARO), the US Air Force Office of Scientific Research (AFOSR) and the Australian Government, among other organisations.</span></em></p><p class="fine-print"><em><span>Andre Saraiva works at Diraq. Through Diraq, he receives funding from Australian Research Council (ARC), UNSW Sydney, US Army Research Office (ARO), the US Air Force Office of Scientific Research (AFOSR) and the Australian Government, among other organisations.</span></em></p>Quantum computers that work at slightly higher temperatures could be cheaper and more accessible.Andrew Dzurak, Scientia Professor Andrew Dzurak, CEO and Founder of Diraq, UNSW SydneyAndre Luiz Saraiva De Oliveira, Solid State Physicist, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2157472023-10-20T12:25:50Z2023-10-20T12:25:50ZQuantum dots − a new Nobel laureate describes the development of these nanoparticles from basic research to industry application<figure><img src="https://images.theconversation.com/files/554426/original/file-20231017-23-nsxqeq.jpg?ixlib=rb-1.1.0&rect=617%2C37%2C7403%2C5450&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Louis Brus, center, shares Nobel recognition with two other quantum dots pioneers.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/screen-shows-this-years-laureates-us-chemist-moungi-bawendi-news-photo/1705016177?adppopup=true">Jonathan Nackstrand/AFP via Getty Images</a></span></figcaption></figure><p><em>The Nobel Prize in chemistry for 2023 goes to three scientists “for the <a href="https://www.nobelprize.org/prizes/chemistry/2023/press-release/">discovery and synthesis of quantum dots</a>.” <a href="https://theconversation.com/becoming-a-nobel-laureate-louis-brus-on-his-discovery-of-quantum-dots-podcast-215915">The Conversation Weekly podcast</a> caught up with one of this trio, physical chemist <a href="https://scholar.google.com/citations?user=GT0oh5QAAAAJ&hl=en&oi=ao">Louis Brus</a>, who did foundational work figuring out that the properties of these nanoparticles depend on their size. Brus’ phone was off when the Nobel reps called to inform him of the good news, but now plenty of people have gotten through with congratulations and advice. Below are edited excerpts from the podcast.</em></p>
<p><strong>When you were working at Bell Labs in the 1980s and discovered quantum dots, it was something of an accident. You were studying solutions of semiconductor particles. And when you aimed lasers at these solutions, called colloids, you noticed that the colors they emitted were not constant.</strong></p>
<p>On the first day we made the colloid, sometimes the spectrum was different. Second and third day, it was normal. There certainly was a surprise when I first saw this change in the spectrum. And so, I began to try to figure out what the heck was going on with that.</p>
<p>I noticed that the property of the particle itself began to change at a very small size.</p>
<p><strong>What you’d found was a quantum dot: a type of nanoparticle that absorbs light and emits it at another wavelength. Crucially, the color of these particles changes depending on the actual size of the particle. How do you even see a quantum dot crystal, since one is just a few hundred thousandths the width of a human hair?</strong></p>
<p>Well, you can’t see them with an optical microscope because they’re smaller than the wavelength of light. There are ways to see them too, using other types of specialist microscopes, such as an electron microscope. And a common way of demonstrating them is to line up a row of brightly colored glass flasks each with a solution of different sized quantum dots inside it.</p>
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<a href="https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of a molecule next to a soccer ball next to a planet" src="https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=186&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=186&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=186&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=234&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=234&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554425/original/file-20231017-21-wzhcci.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=234&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A quantum dot is a crystal that often consists of just a few thousand atoms. In terms of size, it has the same relationship to a soccer ball as a soccer ball has to the size of the Earth.</span>
<span class="attribution"><a class="source" href="https://www.nobelprize.org/prizes/chemistry/2023/press-release/">Johan Jarnestad/The Royal Swedish Academy of Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><strong>One of your fellow laureates, <a href="https://www.nobelprize.org/prizes/chemistry/2023/ekimov/facts/">Alexei Ekimov</a>, was a Russian scientist, and he’d actually observed quantum dots in colored glass, but you weren’t aware of his findings at the time?</strong></p>
<p>Yes, that’s right. The Cold War was going on at that time, and he published in the Russian literature, in Russian. And he wasn’t allowed to travel to the West to talk about his work.</p>
<p>I asked around among all the physicists, was there any work on small particles? I was trying to make a model of the quantum size effects. And they told me no, nobody’s really working on this. Nobody had seen his articles, basically.</p>
<p>I was part of the U.S. chemistry community, doing synthetic chemistry in the laboratory. He was in the glass industry in the Soviet Union, working on industrial technology.</p>
<p>When I eventually found his articles in the technological literature, I wrote a letter to the Soviet Union, with my papers, just to say hello to Ekimov and his colleagues. When the letter came, the KGB came to talk to the Russian scientists, trying to figure out why they had any contact with anybody in the West. But in fact they had never talked to me or anyone in the West when my letter arrived in the mail.</p>
<p><strong>Have you met him since?</strong></p>
<p>Yes, they were able to come out of the Soviet Union during Glasnost, this would be the late 1980s. There’s Ekimov, and then there is his theoretical collaborator <a href="https://scholar.google.com/citations?user=upaytw8AAAAJ&hl=en">Sasha Efros</a>, who now works at the <a href="https://www.nature.com/articles/d41586-023-03179-z">U.S. Naval Research Lab</a>. I met them as soon as they came to the U.S.</p>
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<p><em>Listen to the interview with Louis Brus on The Conversation Weekly podcast. Each week, academic experts tell us about the fascinating discoveries they’re making to understand the world and the big questions they’re still trying to answer.</em></p>
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<p><strong>One of the issues with quantum dots, when you first observed them, was how to actually produce them and keep them stable. Then, in the 1990s, your fellow laureate, <a href="https://scholar.google.com/citations?user=8086TkwAAAAJ&hl=en&oi=ao">Moungi Bawendi</a>, figured this out. What do you think is the most striking thing that you’ve seen quantum dots used in so far?</strong></p>
<p>Usually when a new material is invented, it takes a long time to figure out what it’s really good for. Research scientists, they have ideas, you might use it for this, you might use it for that. But then, if you talk to people in the actual industry, who deal every day with manufacturing problems, these ideas are often not very good.</p>
<p>But the knowledge that we gained, the scientific principles, could be used to help to design new devices.</p>
<p>As far as first applications, people began to try to use them in biological imaging. Biochemists attach quantum dots to other molecules to help map cells and organs. They’ve even been used to detect tumors, and to help guide surgeons during operations.</p>
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<span class="caption">Quantum dot particles were continually improved so they would reliably emit very particular colors.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/quantum-dot-royalty-free-image/1311600163?adppopup=true">Tayfun Ruzgar/iStock via Getty Images Plus</a></span>
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<p>And as scientists kept working to synthesize quantum dots, the quality of the particles kept improving. They were emitting pure colors, rather than distributions of light – like maybe red with a little bit of green, or maybe red with some pink. When you got a better particle, it would be just pure red, for instance.</p>
<p>So then people made the connection to the display industry – computer displays and television displays. In this application, you want to convert electricity into three colors: red, green and blue. You can make up any kind of image, starting with just those three colors in different proportions.</p>
<p>It takes a lot of courage. You have to invest a lot of money to develop the technology, and maybe at the end of it, it’s not good enough, and it will not replace what you already have. And there’s a lot of credit due to the Samsung Corporation in Japan. Hundreds of billions of dollars were invested in the technology of these particles to get them to the point where they could begin to manufacture displays and flat-panel TVs using quantum dots.</p>
<p><strong>Your work is an example of the importance of basic research, of being curious, trying to solve mysteries without a particular endpoint or industrial application in sight. What message would you have for a young chemist starting out today working on such basic research?</strong></p>
<p>The world is a huge place, and you could do basic research in a huge number of different areas. You want to pick a problem where, if you are spectacularly successful and you actually discover something really interesting, it might have some application in the world.</p>
<p>For better or for worse, you have to make a choice in the beginning, and it takes some intuition.</p>
<p>A good way to do it is you pick a subject that you know is important to technology, but there’s no understanding of the science at the present time. It’s a complete black box. Nobody understands the basic principles. That kind of problem, you can begin to take it apart and look to see what the basic steps are.</p>
<p><strong>What changes for you now that you’ve won the Nobel Prize?</strong></p>
<p>Well, this Nobel Prize, for better or for worse, has a special meaning in people’s minds all over the world. Yesterday when the mailman came I happened to be at the front door and he recognized me because my face was in the local newspaper. And he said, “I’ve never shaken the hand of a Nobel laureate before.”</p>
<p>For better or for worse, this is where I am right now, in a special category whether I like it or not. I still have my office in the university, but I don’t have a research group. I’m trying to leave that to the younger people. So this recognition probably means less for my research than it would if I was 40 years old.</p>
<p>I have received congratulations by email from a number of people who won the prize in past years. Their main recommendation is you must learn to say no. People will ask you to do all kinds of crazy things, and your time will be entirely taken up with these honorific university visits and giving little speeches. In order to have a real life and to be productive, you have to say no to all of these extraneous invitations.</p>
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<span class="caption">The Nobel Prize awards ceremony in Stockholm is a black-tie affair.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/general-view-of-the-nobel-prize-awards-ceremony-at-news-photo/1448161113?adppopup=true">Pascal Le Segretain/Getty Images</a></span>
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<p>And they also told me to have fun in Sweden! It’s an extremely elaborate schedule of events for that week in December when this award ceremony is. Extremely fancy. American culture, physics culture is different – if you win a prize from the American Physical Society, it’s a very low-key event. You just show up in an auditorium. It’s not even necessary to wear a suit.</p>
<p>So I will take my family, my grandchildren to Sweden and we’ll try to enjoy this as a great vacation.</p><img src="https://counter.theconversation.com/content/215747/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louis Brus does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Louis Brus explains some of the foundational research – and how even the letter carrier wants to shake your hand when you’ve just won a Nobel Prize.Louis Brus, Professor Emeritus of Chemistry, Columbia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2159152023-10-19T10:21:23Z2023-10-19T10:21:23ZBecoming a Nobel laureate: Louis Brus on his discovery of quantum dots – podcast<p>Imagine a particle so small that it’s the same relative size to a football as that ball is to the planet Earth. That’s the size of a quantum dot – a type of nanocrystal that changes colour depending on its size, and was once thought impossible to actually produce. </p>
<p>Today, they’re found in some <a href="https://theconversation.com/nobel-prize-in-chemistry-awarded-for-quantum-dot-technology-that-gave-us-todays-high-definition-tvs-214976">high-definition television and computer screens</a>, and are used in medicine to map what’s happening in cells and even tumours. And three scientists who helped discover and produce these quantum dots have now been awarded the <a href="https://www.nobelprize.org/prizes/chemistry/">2023 Nobel prize in chemistry</a>. </p>
<p>In this week’s episode of <a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901"><em>The Conversation Weekly</em></a> podcast, we speak to Louis Brus, one of these new Nobel laureates and an emeritus professor of chemistry at Columbia University in New York, about his work on quantum dots and what winning the accolade means to him. </p>
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<p>Brus wasn’t actually looking for quantum dots, the particles that would go on to win him a Nobel prize, when he first discovered them. “We knew that they existed, at least in principle … but I wasn’t trying to do this,” he tells us. It was the early 1980s and Brus was working at <a href="https://www.nature.com/articles/s42254-022-00426-6">Bell Labs</a>, an American industrial research company famous for its long list of alumni who have gone on to win a Nobel prize. </p>
<p>Brus was mixing up solutions containing different types of semiconductor particle, aiming lasers at them to see what kind of photochemistry would happen on their surfaces. “I noticed that the property of the particle itself began to change at a very small size,” he remembers. What he’d observed were quantum dots: nanocrystals that absorb light and emit it at another wavelength, with the colour changing depending on the size of the particle. </p>
<p>Brus wasn’t the first scientist to have observed this phenomenon. A Russian scientist called Alexei Ekimov had also observed quantum dots in coloured glass a few years earlier, but because of the cold war, Brus was unaware that Ekimov had published journal articles about it in Russian. </p>
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Read more:
<a href="https://theconversation.com/quantum-dots-a-new-nobel-laureate-describes-the-development-of-these-nanoparticles-from-basic-research-to-industry-application-215747">Quantum dots − a new Nobel laureate describes the development of these nanoparticles from basic research to industry application</a>
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<p>“We did not read the journals in the west and he was not allowed to travel to the west to talk about his work,” Brus explains. Ekimov, along with a third chemist Moungi Bawendi, who perfected the synthesis of quantum dots in the 1990s, now share the 2023 Nobel prize in chemistry with Brus. </p>
<p>Listen to our full interview with Louis Brus on <a href="https://podfollow.com/the-conversation-weekly/view">The Conversation Weekly</a> podcast to hear more about his discovery, its applications, and his advice for young chemists starting out today.</p>
<p>A <a href="https://cdn.theconversation.com/static_files/files/2881/The_Conversation_Weekly_Quantum_Dots_episode_transcript.pdf?1698330817">transcript of this episode</a> is now available.</p>
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<p><em>This episode was written and produced by Gemma Ware and Katie Flood with assistance from Mend Mariwany. Eloise Stevens does our sound design, and our theme music is by Neeta Sarl. Gemma Ware is the executive producer of the show.</em></p>
<p><em>Newsclips in this episode are from the <a href="https://www.youtube.com/channel/UC-V6odR7HzLCuqjYeowPjLA">Nobel Prize</a>.</em></p>
<p><em>You can find us on Twitter <a href="https://twitter.com/TC_Audio">@TC_Audio</a>, on Instagram at <a href="https://www.instagram.com/theconversationdotcom/">theconversationdotcom</a> or <a href="mailto:podcast@theconversation.com">via email</a>. You can also subscribe to The Conversation’s <a href="https://theconversation.com/newsletter">free daily email here</a>.</em></p>
<p><em>Listen to <em>The Conversation Weekly</em> via any of the apps listed above, download it directly via our <a href="https://feeds.acast.com/public/shows/60087127b9687759d637bade">RSS feed</a> or find out <a href="https://theconversation.com/how-to-listen-to-the-conversations-podcasts-154131">how else to listen here</a>.</em></p><img src="https://counter.theconversation.com/content/215915/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louis Brus does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Louis Brus, one of the newest Nobel laureates in chemistry, speaks to The Conversation Weekly podcast.Gemma Ware, Editor and Co-Host, The Conversation Weekly Podcast, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2149762023-10-05T09:20:07Z2023-10-05T09:20:07ZNobel prize in chemistry awarded for ‘quantum dot’ technology that gave us today’s high definition TVs<p>The 2023 Nobel prize in chemistry <a href="https://www.nobelprize.org/prizes/chemistry/2023/press-release/">has been awarded</a> to a trio for the discovery and development of particles so tiny they were once thought too small to be possible. They are widely used in television screens, LED lights and to guide surgeons removing cancer tumours.</p>
<p><a href="https://chemistry.mit.edu/profile/moungi-bawendi/">Moungi G. Bawendi</a> from Massachusetts Institute of Technology (MIT) in the US, <a href="https://www.chem.columbia.edu/content/louis-e-brus">Louis E. Brus </a>from Columbia University in the US and <a href="https://www.nobelprize.org/prizes/chemistry/2023/ekimov/facts/">Alexei I. Ekimov</a> from Nanocrystals Technology Inc. in New York in the US will share the prize sum of 11 million Swedish kronor (£822,910).</p>
<p>The trio all contributed to the discovery and development of quantum dots, which are nanoparticles (particles between one to 100 nanometres in size) so small that their size actually determines their properties. </p>
<p>Such particles obey the rules of quantum mechanics, governing nature on the smallest of scales, meaning they have optical and electronic properties that are different from those of larger particles. </p>
<p>For example, quantum dots absorb light and emit it at another wavelength – with the resulting colour depending on the particle’s size.</p>
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<a href="https://theconversation.com/the-future-is-bright-the-future-is-quantum-dot-televisions-35765">The future is bright, the future is ... quantum dot televisions</a>
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<p>The work started in the early 1980s when Ekimov discovered how to create coloured glass using nanoparticles of copper chloride. A few years later, Brus was the first scientist to prove that nanoparticles in a fluid exhibit quantum effects.</p>
<p>In 1993, Bawendi revolutionised the chemical production of quantum dots, which meant they could be used for practical applications such as in technology and healthcare. </p>
<figure class="align-center ">
<img alt="Drawing of quantum dots absorbing light." src="https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=561&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=561&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=561&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=705&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=705&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552064/original/file-20231004-19-ych3n5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=705&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">How quantum dots absorb light.</span>
<span class="attribution"><span class="source">Johan Jarnestad/The Royal Swedish Academy of Sciences</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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</figure>
<p>So why are quantum dots so important in the fields of display devices and medical imaging?</p>
<p>As technology for home and commercial use has increased in complexity, so has the resolution and contrast performance of display screens. High definition displays were introduced from 2003 to 2009 where they became the dominant display type available to the public. The successor, ultra high definition, has become today’s standard. </p>
<p>Quantum dots helped increase the range of display colours to more accurately reflect the range of colours the human eye can naturally perceive. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/CiDB6OBx3Qo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>A major problem for technology researchers was how to increase the pallet of colours and sub-colours to do this. Quantum dots give us that flexibility and control.</p>
<p>Quantum dots ultimately offer more accuracy when developing technologies because you can change their properties, such as colour, by changing their size. </p>
<p>Nanotechnology techniques allow us to create molecules of different sizes, to emit different wavelengths of light more accurately and consistently. Quantum dots are bringing us much closer to display screens that reproduce the full range of colours humans can discern. </p>
<p>Quantum dots have been a game changer for medical imaging, too. They have helped create more advanced systems for tumour detection, to study human cells, angiograms (a type of X-ray to examine blood vessels) and even camera-guided surgery and robotic surgery. </p>
<p>Researchers studying the immune system and chemical reactions in the body rely on quantum dots to illustrate their studies more accurately. </p>
<p>We still have not realised the full potential of quantum dots. They have already made their mark on the technology and medical sectors. But they also have the potential to create more accurate imaging for other sectors too, such as astronomy. They might even help create next generation solar cell technology to improve solar cell efficiency for power production.</p>
<p>Not so long ago, we didn’t know quantum dots had different frequencies. Now they are an important part of the technology in our TVs, our lights and the medical science that treats and diagnoses diseases. It’s hard to say how we will be using quantum dots in the future - the limit may be our imagination.</p><img src="https://counter.theconversation.com/content/214976/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laurence Murphy consults for JVC , Pansonic and SMPTE.</span></em></p>Quantum dot technology has also helped revolutionise medical imagining.Laurence Murphy, Senior Lecturer & Researcher in Media Technology, University of SalfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2150152023-10-04T21:19:46Z2023-10-04T21:19:46ZQuantum dots are part of a revolution in engineering atoms in useful ways – Nobel Prize for chemistry recognizes the power of nanotechnology<figure><img src="https://images.theconversation.com/files/552184/original/file-20231004-19-i1snbm.jpg?ixlib=rb-1.1.0&rect=143%2C24%2C3655%2C2727&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Flasks of quantum dots fluorescing at the Nobel Prize announcement.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/laboratory-flasks-are-used-for-explanation-during-the-news-photo/1705001725">Jonathan Nackstrand/AFP via Getty Images</a></span></figcaption></figure><p>The 2023 Nobel Prize for chemistry <a href="https://www.nobelprize.org/prizes/chemistry/2007/summary/">isn’t the</a> <a href="https://www.nobelprize.org/prizes/physics/1986/summary/">first Nobel</a> <a href="https://www.nobelprize.org/prizes/chemistry/2010/summary/">awarded for</a> <a href="https://www.nobelprize.org/prizes/chemistry/2016/summary/">research in</a> <a href="https://www.nobelprize.org/prizes/chemistry/1996/summary/">nanotechnology</a>. But it is perhaps the most colorful application of the technology to be associated with the accolade.</p>
<p>This year’s prize recognizes <a href="https://scholar.google.com/citations?user=8086TkwAAAAJ&hl=en&oi=ao">Moungi Bawendi</a>, <a href="https://scholar.google.com/citations?user=GT0oh5QAAAAJ&hl=en&oi=ao">Louis Brus</a> and <a href="https://www.nobelprize.org/prizes/chemistry/2023/ekimov/facts">Alexei Ekimov</a> for the <a href="https://www.nobelprize.org/prizes/chemistry/2023/press-release/">discovery and development of quantum dots</a>. For many years, these <a href="https://doi.org/10.1021/acsanm.0c01386">precisely constructed nanometer-sized particles</a> – just a few hundred thousandths the width of a human hair in diameter – were the darlings of nanotechnology pitches and presentations. As a <a href="https://scholar.google.com/citations?user=b8NhWc4AAAAJ&hl=en">researcher</a> and <a href="https://en.wikipedia.org/wiki/Andrew_D._Maynard">adviser</a> on nanotechnology, <a href="https://2020science.org/wp-content/uploads/2009/01/maynard-ucla-090417-handouts.pdf">I’ve even used them myself</a> when talking with developers, policymakers, advocacy groups and others about the promise and perils of the technology.</p>
<p>The origins of nanotechnology predate Bawendi, Brus and Ekimov’s work on quantum dots – the physicist Richard Feynman speculated on what could be possible through nanoscale engineering <a href="http://calteches.library.caltech.edu/1976/">as early as 1959</a>, and engineers like Erik Drexler were speculating about the possibilities of atomically precise manufacturing <a href="https://www.penguinrandomhouse.com/books/42881/engines-of-creation-by-k-eric-drexler/">in the the 1980s</a>. However, this year’s trio of Nobel laureates were part of the earliest wave of modern nanotechnology where researchers began <a href="https://andrewmaynard.substack.com/p/living-in-a-material-world">putting breakthroughs in material science to practical use</a>.</p>
<p>Quantum dots brilliantly <a href="https://www.britannica.com/science/fluorescence">fluoresce</a>: They absorb one color of light and reemit it nearly instantaneously as another color. A vial of quantum dots, when illuminated with broad spectrum light, shines with a single vivid color. What makes them special, though, is that their color is determined by how large or small they are. Make them small and you get an intense blue. Make them larger, though still nanoscale, and the color shifts to red.</p>
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<a href="https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of colorful circles of different sizes" src="https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=186&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=186&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=186&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=234&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=234&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552172/original/file-20231004-26-sy0ozo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=234&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The wavelength of light a quantum dot emits depends on its size.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.3389/fnins.2015.00480">Maysinger, Ji, Hutter, Cooper</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>This property has led to many arresting images of rows of vials containing quantum dots of different sizes going from a striking blue on one end, through greens and oranges, to a vibrant red at the other. So eye-catching is this demonstration of the power of nanotechnology that, in the early 2000s, quantum dots became iconic of the strangeness and novelty of nanotechnology.</p>
<p>But, of course, quantum dots are more than a visually attractive parlor trick. They demonstrate that unique, controllable and useful interactions between matter and light can be achieved through engineering the physical form of matter – modifying the size, shape and structure of objects, for instance – rather than playing with the chemical bonds between atoms and molecules. The distinction is an important one, and it’s at the heart of modern nanotechnology.</p>
<h2>Skip chemical bonds, rely on quantum physics</h2>
<p>The wavelengths of light that a material absorbs, reflects or emits are usually determined by the chemical bonds that bind its constituent atoms together. <a href="https://www.sciencedirect.com/topics/engineering/synthetic-dye">Play with the chemistry of a material</a> and it’s possible to fine-tune these bonds so that they give you the colors you want. For instance, some of the earliest dyes <a href="https://thedreamstress.com/2013/09/terminology-what-are-aniline-dyes-or-the-history-of-mauve-and-mauveine/">started with a clear substance such as aniline</a>, transformed through chemical reactions to the desired hue.</p>
<p>It’s an effective way to work with light and color, but it also leads to products that <a href="https://www.sciencemuseum.org.uk/objects-and-stories/chemistry/colourful-chemistry-artificial-dyes">fade over time as those bonds degrade</a>. It also frequently involves using chemicals that are <a href="https://doi.org/10.1016/B978-0-12-822850-0.00013-2">harmful to humans and the environment</a>.</p>
<p>Quantum dots work differently. Rather than depending on chemical bonds to determine the wavelengths of light they absorb and emit, they rely on very small clusters of semiconducting materials. It’s the <a href="https://www.britishcouncil.org/voices-magazine/what-quantum-dot">quantum physics of these clusters</a> that then determines what wavelengths of light are emitted – and this in turn depends on how large or small the clusters are.</p>
<p>This ability to tune how a material behaves by simply changing its size is a game changer when it comes to the intensity and quality of light that quantum dots can produce, as well as their resistance to bleaching or fading, their novel uses and – if engineered smartly – their toxicity.</p>
<p>Of course, few materials are completely nontoxic, and quantum dots are no exception. Early quantum dots were often based on cadmium selenide for instance – the component materials of which are toxic. However, the <a href="https://theconversation.com/are-quantum-dot-tvs-and-their-toxic-ingredients-actually-better-for-the-environment-35953">potential toxicity of quantum dots needs to be balanced</a> by the likelihood of release and exposure and how they compare with alternatives. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="people walk past colorful multi-screen display at a trade show" src="https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552185/original/file-20231004-21-o7term.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Quantum dots are now a normal part of many consumer items, including televisions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/trade-visitors-walk-past-televisions-with-quantum-dots-news-photo/1040134228">Soeren Stache/picture alliance via Getty Images</a></span>
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<p>Since its earlier days, quantum dot technology has evolved in safety and usefulness and has found its way into an increasing number of products, from <a href="https://www.wired.com/2015/01/primer-quantum-dot/">displays</a> and <a href="https://doi.org/10.1021/acs.chemrev.2c00695">lighting</a>, to <a href="https://doi.org/10.1016/B978-0-323-88431-0.00025-9">sensors</a>, <a href="https://doi.org/10.2147/IJN.S357980">biomedical applications</a> and more. In the process, some of their novelty has perhaps worn off. It can be hard to remember just how much of a quantum leap the technology is that’s being used to promote the <a href="https://www.cnet.com/tech/home-entertainment/this-top-secret-prototype-display-will-blow-your-mind/">latest generation of flashy TVs</a>, for instance.</p>
<p>And yet, quantum dots are a pivotal part of a technology transition that’s revolutionizing how people work with atoms and molecules.</p>
<h2>‘Base coding’ on an atomic level</h2>
<p>In my book “<a href="https://andrewmaynard.net/films-from-the-future/">Films from the Future: the Technology and Morality of Sci-Fi Movies</a>,” I write about the concept of “<a href="https://andrewmaynard.substack.com/p/how-our-mastery-of-biological-physical-and-cyber-base-code-is-transforming-how-we-think-about-b2eae9d589d0">base coding</a>.” The idea is simple: If people can manipulate the most basic code that defines the world we live in, we can begin to redesign and reengineer it. </p>
<p>This concept is intuitive when it comes to computing, where programmers use the “base code” of 1’s and 0’s, albeit through higher level languages. It also makes sense in biology, where scientists are becoming increasingly adept at reading and writing the base code of DNA and RNA – in this case, using the chemical bases adenine, guanine, cytosine and thymine as their coding language. </p>
<p>This ability to work with base codes also extends to the material world. Here, the code is made up of atoms and molecules and how they are arranged in ways that lead to novel properties.</p>
<p>Bawendi, Brus and Ekimov’s work on quantum dots is a perfect example of this form of material-world base coding. By precisely forming small clusters of particular atoms into spherical “dots,” they were able to tap into novel quantum properties that would otherwise be inaccessible. Through their work they demonstrated the transformative power that comes through coding with atoms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="alt" src="https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=514&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=514&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=514&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=646&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=646&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552183/original/file-20231004-25-wr0i0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=646&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An example of ‘base coding’ using atoms to create a material with novel properties is a single molecule ‘nanocar’ crafted by chemists that can be controlled as it ‘drives’ over a surface.</span>
<span class="attribution"><a class="source" href="https://news.rice.edu/news/2020/rice-rolls-out-next-gen-nanocars">Alexis van Venrooy/Rice University</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>They paved the way for increasingly sophisticated nanoscale base coding that is now leading to products and applications that would not be possible without it. And they were part of the inspiration for a <a href="https://www.nature.com/articles/d41586-022-02146-4">nanotechnology revolution</a> that is continuing to this day. Reengineering the material world in these novel ways far transcends what can be achieved through more conventional technologies.</p>
<p>This possibility was captured in a 1999 U.S. National Science and Technology Council report with the title <a href="https://trid.trb.org/view/636880">Nanotechnology: Shaping the World Atom by Atom</a>. While it doesn’t explicitly mention quantum dots – an omission that I’m sure the authors are now kicking themselves over – it did capture just how transformative the ability to engineer materials at the atomic scale could be.</p>
<p>This atomic-level shaping of the world is exactly what Bawendi, Brus and Ekimov aspired to through their groundbreaking work. They were some of the first materials “base coders” as they used atomically precise engineering to harness the quantum physics of small particles – and the Nobel committee’s recognition of the significance of this is well deserved.</p><img src="https://counter.theconversation.com/content/215015/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Maynard has previously received funding for nanotechnology-based work from the National Institutes of Health, the National Science Foundation, and the Pew Charitable Trusts</span></em></p>Quantum dots are a prime example of the way nanotechnology engineers materials at an atomic scale.Andrew Maynard, Professor of Advanced Technology Transitions, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1237432019-10-15T11:16:56Z2019-10-15T11:16:56ZQuantum dots that light up TVs could be used for brain research<figure><img src="https://images.theconversation.com/files/296465/original/file-20191010-188829-18m0ayu.jpg?ixlib=rb-1.1.0&rect=3%2C177%2C392%2C282&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Red quantum dots glow inside a rat brain cell.</span> <span class="attribution"><a class="source" href="https://doi.org/10.1039/C9NA00334G">Nanoscale Advances, 2019, 1, 3424 - 3442</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>While many people love colorful photos of landscapes, flowers or rainbows, some biomedical researchers treasure vivid images on a much smaller scale – as tiny as one-thousandth the width of a human hair. </p>
<p>To study the micro world and help advance medical knowledge and treatments, these scientists use fluorescent nano-sized particles.</p>
<p>Quantum dots are one type of nanoparticle, more commonly known for their use in TV screens. They’re super tiny crystals that can transport electrons. When UV light hits these semiconducting particles, they can emit light of various colors.</p>
<p>That fluorescence allows scientists to use them to study hidden or otherwise cryptic parts of cells, organs and other structures.</p>
<p>I’m part of a group of nanotechnology and neuroscience researchers at the University of Washington investigating <a href="https://doi.org/10.1039/C9NA00334G">how quantum dots behave in the brain</a>. </p>
<p>Common brain diseases are estimated to cost the U.S. <a href="https://doi.org/10.1002/ana.24897">nearly US$800 billion</a> annually. These diseases – including Alzheimer’s disease and neurodevelopmental disorders – are hard to diagnose or treat.</p>
<p>Nanoscale tools, such as quantum dots, that can capture the nuance in complicated cell activities hold promise as brain-imaging tools or drug delivery carriers for the brain. But because there are many reasons to be concerned about their use in medicine, mainly related to health and safety, it’s important to figure out more about how they work in biological systems.</p>
<h2>Quantum dots as next-generation dyes</h2>
<p>Researchers first <a href="https://en.wikipedia.org/wiki/Quantum_dot">discovered quantum dots in the 1980s</a>. These tiny particles are different from other crystals in that they can produce different colors depending on their size. They are so small that that they are sometimes called zero-dimensional or artificial atoms.</p>
<p>The most commonly known use of quantum dots nowadays may be TV screens. Samsung launched their <a href="https://theconversation.com/the-future-is-bright-the-future-is-quantum-dot-televisions-35765">QLED TVs in 2015</a>, and a few other companies followed not long after. But scientists have been eyeing quantum dots for almost a decade. Because of their unique optical properties – they can produce thousands of bright, sharp fluorescent colors – scientists started using them as optical sensors or imaging probes, particularly in medical research.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296742/original/file-20191012-96217-5efo1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tubes of quantum dots emit bright, colorful light.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/glass-tubes-quantum-dots-perovskite-nanocrystals-700118455">rebusy/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Scientists have long used various dyes to tag cells, organs and other tissues to view the inner workings of the body, whether that be for diagnosis or for fundamental research.</p>
<p>The most common dyes have some significant problems. For one, their color often cannot survive very long in cells or tissues. <a href="https://doi.org/10.1038/nbt764">They may fade in a matter of seconds or minutes</a>. For some types of research, such as tracking cell behaviors or delivering drugs in the body, these organic dyes simply do not last long enough. </p>
<p>Quantum dots would solve those problems. They are very bright and fade very slowly. <a href="https://doi.org/10.1186/1742-2094-9-22">Their color can still stand out after a month</a>. Moreover, they are too small to physically affect the movement of cells or molecules.</p>
<p>Those properties make quantum dots popular in medical research. Nowadays quantum dots are mainly used for high resolution 3D imaging of cells or molecules, or real-time tracking probes inside or outside of animal bodies that can last for an extended period.</p>
<p>But their use is still restricted to animal research, because scientists are <a href="https://doi.org/10.2217/nnm.12.152">concerned about their use in human beings</a>. Quantum dots commonly contain cadmium, a heavy metal that is highly poisonous and carcinogenic. They may <a href="https://doi.org/10.1016/j.biomaterials.2011.10.070">leak the toxic metal</a> or form an unstable aggregate, causing cell death and <a href="https://doi.org/10.1038/nnano.2007.223">inflammation</a>. Some organs may tolerate a small amount of this, but the brain cannot withstand such injury.</p>
<h2>How quantum dots behave in the brain</h2>
<p>My colleagues and I believe an important first step toward wider use of quantum dots in medicine is understanding how they behave in biological environments. That could help scientists design quantum dots suitable for medical research and diagnostics: When they’re injected into the body, they need to stay small particles, be not very toxic and able to target specific types of cells.</p>
<p>We looked at the <a href="https://doi.org/10.1039/C9NA00334G">stability, toxicity and cellular interactions of quantum dots in the developing brains of rats</a>. We wrapped the tiny quantum dots in different chemical “coats.” Scientists believe these coats, with their various chemical properties, control the way quantum dots interact with the biological environment that surrounds them. Then we evaluated how quantum dots performed in three commonly used brain-related models: cell cultures, rat brain slices and individual live rats.</p>
<p>We found that different chemical coats give quantum dots different behaviors. Quantum dots with a polymer coat of polyethylene glycol (PEG) were the most promising. They are more stable and less toxic in the rat brain, and at a certain dose don’t kill cells. It turns out that PEG-coated quantum dots activate a biological pathway that ramps up the production of a molecule that detoxifies metal. It’s a protective mechanism embedded in the cells that happens to ward off injury by quantum dots. </p>
<p>Quantum dots are also “eaten” by <a href="https://www.sciencedirect.com/topics/neuroscience/microglia">microglia</a>, the brain’s inner immune cells. These cells regulate inflammation in the brain and are involved in multiple brain disorders. Quantum dots are then transported to the microglia’s lysosomes, the cell’s garbage cans, for degradation.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296743/original/file-20191012-96226-k0ck7i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Quantum dots encounter different conditions in a cell, a slice of brain, or a live animal.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/rat-brain-vector-illustration-625395848">Beatriz Gascon J/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>But we also discovered that the behaviors of quantum dots vary slightly between cell cultures, brain slices and living animals. The simplified models may demonstrate how a part of the brain responds, but they are not a substitute for the entire organ. </p>
<p>For example, cell cultures contain brain cells but lack the connected cellular networks that tissues have. Brain slices have more structure than cell cultures, but they also lack the full organ’s blood-brain barrier – its “Great Wall” that prevents foreign objects from entering.</p>
<h2>What’s the future for quantum dots?</h2>
<p>Our results offer a warning: Nanomedicine research in the brain makes no sense without carefully considering the organ’s complexity. </p>
<p>That said, we think our findings can help researchers design quantum dots that are more suitable for use in living brains. For example, our research shows that PEG-coated quantum dots remain stable and relatively nontoxic in living brain tissue while having great imaging performance. We imagine they could be used to track real-time movements of viruses or cells in the brain.</p>
<p>In the future, along with MRI or CT scans, quantum dots may become vital imaging tools. They might also be used as traceable carriers that deliver drugs to specific cells. Ultimately, though, for quantum dots to realize their biomedical potential beyond research, scientists must address health and safety concerns. </p>
<p>Although there’s a long way to go, my colleagues and I hope the future for quantum dots may be as bright and colorful as the artificial atoms themselves.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/123743/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mengying Zhang does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>These tiny nanoparticles might provide a new way to see what’s happening in the brain and even deliver treatments to specific cells – if researchers figure out how to use them safely and effectively.Mengying Zhang, PhD Candidate in Molecular Engineering and Sciences, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1034872018-09-21T11:07:54Z2018-09-21T11:07:54ZSamsung’s foldable phone could soon be a reality<figure><img src="https://images.theconversation.com/files/237125/original/file-20180919-158225-4dixv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://news.samsung.com/us/samsung-displays-unbreakable-panel-certified-underwriters-laboratories/">Samsung</a></span></figcaption></figure><p>We rarely see a truly remarkable new technology more than once a decade. After <a href="https://theconversation.com/why-are-flexible-computer-screens-taking-so-long-to-develop-53143">years of undelivered promises</a>, such a technology looks finally set to enter the market: the flexible computer screen.</p>
<p>Imagine, a tablet display you can fold up and put in your pocket, a smart watch whose strap is the screen, or a handbag that is also a monitor and keyboard. Nokia <a href="https://www.cam.ac.uk/news/cambridge-and-nokia-introduce-new-stretchable-and-flexible-mobile-phone-concept">originally called</a> this proposed technology “Morph” back in 2008 because of the plethora of applications it would make possible. Now it looks like it will become a reality.</p>
<p>After nearly <a href="https://www.militaryaerospace.com/articles/print/volume-15/issue-10/features/technology-focus/display-technology-leaps-to-the-next-generation.html">two decades of work</a>, Samsung <a href="https://bgr.com/2018/09/05/samsung-foldable-galaxy-phone-more-design-details/">is rumoured</a> to be getting ready for the launch of the first flexible smartphone. The company’s head of mobile <a href="https://www.cnbc.com/2018/09/04/samsung-unveiling-a-foldable-smartphone-this-year.html">recently said</a> it was “time to deliver” such a phone, and that the development process for it was “nearly concluded”.</p>
<p>But perhaps more significantly, the Samsung Display division of the company <a href="https://news.samsung.com/us/samsung-displays-unbreakable-panel-certified-underwriters-laboratories/">recently said</a> it had developed an “unbreakable smartphone panel” that had passed rigorous safety testing. Even after being subjected to temperatures of 71˚C and -32˚C, and dropped from a height of 1.8 metres, the display showed no signs of damage and functioned normally. </p>
<p>This display is a flexible organic light emitting diode (OLED) panel made of an unbreakable surface with a plastic overlay window attached to it, making it simultaneously lightweight and tough as glass but a lot more robust. Manufacturers have yearned for many years to make displays with flexible, bendable properties and a paper-like feel with electronic functionality. If Samsung has truly found a way to protect a flexible OLED then it has solved a major technical challenge in removing the need for the glass screens used on most other displays today.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/237326/original/file-20180920-129859-13xw3qt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Smartphone of the near future?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/flexible-smartphone-concept-illustration-screen-layout-159538328?src=kg8nz5EEKv0q5zuQsPTtGg-1-2">Grzegorz Petrykowski/Shutterstock</a></span>
</figcaption>
</figure>
<p>Glass was originally needed to actually stop displays from bending. Old-fashioned liquid crystal displays easily distorted when bent because the molecules in the liquid inside them would become misaligned. <a href="https://www.whathifi.com/advice/what-oled-tech-benefits-best-oled-tvs-and-oled-phones">Today’s OLED screens</a> are based on a solid layer of light-emitting material that doesn’t easily distort in this way. But glass is also used to protect the organic molecules in an OLED display from being degraded by water vapour and other gases that would shorten their lifespan. Until now, encapsulating displays in flexible plastic hasn’t been enough to protect them.</p>
<p>A more advanced, <a href="https://www.androidauthority.com/quantum-dot-vs-oled-explained-659321/">better quality</a> kind of screen known as a <a href="https://www.cnet.com/news/how-quantum-dots-could-challenge-oled-for-best-tv-picture/">quantum dot light emitting diode</a> (QLED) display can also be made flexible. These use nano-crystals to produce high-quality, pure and sharp monochromatic light. They convert the backlight into the pure basic colours without the use of filters. But encapsulating QLED displays is even harder than OLEDs and so are likely to take a lot longer to turn into a flexible product.</p>
<h2>Increasing flexibility</h2>
<p>Samsung’s flexible OLED screen is likely to be have the most basic level of flexibility, with the ability to be bent and curved without distorting the display but not completely folded. The level of flexibility might be increased as the nanotechnology in the screens improves, as the nanowires used to carry electricity through the displays become <a href="https://www.nature.com/articles/srep45903">more flexible at smaller diametres</a>. </p>
<p>In the future we may eventually see rollable displays that can be rolled up like a scroll. The most advanced type of flexible screen will be one that can be folded or even crushed like a sheet of paper and still produce a seamless image. The newest and most exciting idea for creating these screens is to use <a href="https://www.nature.com/articles/s41467-017-00399-6">new “auxtetic” materials</a>, which become thicker as they are stretched rather than thinner.</p>
<p>These materials can absorb high energy impacts and are made of single molecules or crystals that can self-align once distorted. They are typically lightweight and would allow the creations of screens with hinge-like design features that can flex significantly.</p>
<p>In the meantime, appears that within a year we could be able to snuggle up in bed reading from a screen that we don’t have to worry about damaging if we fall asleep on it. I, for one, can’t wait to get my hands on this new tech.</p><img src="https://counter.theconversation.com/content/103487/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ravi Silva does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>After two decades of work, the technical challenges of a bendable screen may have been overcome.Ravi Silva, Director, Advanced Technology Institute, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/974762018-05-31T11:03:44Z2018-05-31T11:03:44ZElon Musk says nanotechnology is ‘BS’ – here’s how it’s already changing the world<figure><img src="https://images.theconversation.com/files/221149/original/file-20180531-69497-1g96i2k.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C4508&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/colorful-background-disco-posters-748875727?src=ROD7BsVt0r7gzrKCP_nDyA-1-46">Shutterstock</a></span></figcaption></figure><p>You might expect Elon Musk, the business magnate, engineer and serial entrepreneur would be a fan of all things techy. After all, his radical enterprises are built on pushing science to its limit. He’s behind a raft of visionary projects ranging from Tesla’s <a href="https://theconversation.com/could-teslas-model-x-drive-us-towards-electric-cars-for-all-48452">driverless electric cars</a> and SpaceX’s <a href="https://theconversation.com/how-to-launch-a-rocket-into-space-and-then-land-it-on-a-ship-at-sea-57675">self-landing reusable rockets</a> to plans for 1,000kph <a href="https://theconversation.com/how-we-can-make-super-fast-hyperloop-travel-a-reality-71100">“hyperloop” trains</a>. But it appears there is a size limit to Musk’s technophilia. He recently tweeted that he thinks nanotechnology is “BS”.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"999579712484790272"}"></div></p>
<p>Folks on Twitter got a bit cross about this blanket dismissal of a field of research that bridges engineering, chemistry and physics. But Musk stuck to his guns, backing up his assertion by linking to Uncylcopedia, a crowd-edited satirical website, of all things.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"999808730106445824"}"></div></p>
<p>So is nanotech just a buzzword used to jazz up some otherwise dull research? Or is it a real branch of scientific discovery that’s actually making a difference to the world?</p>
<p>Nano means small, really small. One nanometre is just one billionth of metre. At this scale we’re dealing with individual molecules and atoms (a carbon atom is about 0.3 nanometres across). So nanotech is about arranging matter that’s between one nanometre and 100 nanometres across in at least one dimension, to create usable medicines, electronics and materials.</p>
<p>The idea of deliberately doing science and engineering at this scale may well have started <a href="https://www.aps.org/publications/apsnews/201611/nanotechnology.cfm">back in 1959</a>, with a talk entitled <a href="http://media.wiley.com/product_data/excerpt/53/07803108/0780310853.pdf">There’s Plenty of Room at the Bottom</a>
by the great physicist Richard Feynman. But, in fact, people in ancient times used nanotechnology to create <a href="https://www.theguardian.com/nanotechnology-world/nanotechnology-is-ancient-history">stunning works of art</a>, without realising the scales at which they were manipulating matter.</p>
<h2>Quantum dots</h2>
<p>Today we’ve purposefully harnessed nanotechnology to do some incredible things. Take quantum dots. They may sound like the name of a <a href="https://www.quantumdotmusic.com/about-1/">Belgian indie band</a> but, in fact, these real and incredibly versatile nanomaterials are being used in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5546783/">medical imaging</a>, display technologies and <a href="https://www.nature.com/articles/s41467-017-01362-1">photovoltaic solar cells</a>.</p>
<p>A quantum dot is a particle of semiconducting material just a few nanometres in diameter. Due to their miniscule size, they have electronic properties that sit between what you would expect for a single molecule and a larger bulk material. One of the most useful outcomes of this is that the dots fluoresce (glow) with a colour that depends on the size of the particle. This means that by tweaking the size of the dot you can tune the colours they give off. And that property makes them an ideal candidate for use in your <a href="https://theconversation.com/the-future-is-bright-the-future-is-quantum-dot-televisions-35765">next flat screen TV</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=351&fit=crop&dpr=1 600w, https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=351&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=351&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=441&fit=crop&dpr=1 754w, https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=441&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/221154/original/file-20180531-69508-6ie6q0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=441&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Nanopores mean faster DNA sequencing.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Nanobiotechnology</h2>
<p>Nature has a jump on us when it comes to nanotech. The protein molecules that replicate your DNA, digest your food and fight off infections are all nano-sized machines perfectly evolved to do a specific job in your bodies. This makes them ideal places to look for inspiration when trying to engineer something on the nanoscale.</p>
<p>A great example of this in action is a technique known as <a href="https://nanoporetech.com/how-it-works">nanopore DNA sequencing</a>. This technology involves proteins called porins that are normally used by bacteria to allow materials to enter and leave the cells. The porins are placed in a membrane to create channels or pores through it, and an electrical field is then applied. When DNA is forced through the pores the electrical current changes in response to the part of the DNA molecule (the base) that is in the pore.</p>
<p>By measuring the current as the molecule passes through the pore you can work out what the bases that comprise it are and sequence the DNA. This can be done at breakneck speed – up to <a href="https://www.nature.com/articles/nbt.4060">450 bases a second</a> – using a tiny desktop device.</p>
<h2>Graphene</h2>
<p>You can’t mention nanotech without graphene cropping up. It’s been dubbed a <a href="https://theconversation.com/from-pencil-to-high-speed-internet-graphene-is-a-modern-wonder-3146">wonder material</a> due to its strength, conductivity and elasticity. Made up of two-dimensional arrays of carbon atoms arranged in a honeycomb pattern, graphene sheets can be just a few atoms thick but with a total area nearer the <a href="https://phys.org/news/2017-07-large-single-crystal-graphene.html">size of a poster</a>. </p>
<p>When mixed with resins and plastics, the resulting material will be incredibly strong and lightweight. Graphene-based <a href="https://www.graphene-info.com/graphene-composites">composite materials</a> are already being used for a range of applications including <a href="http://donbasile.me/3-ways-graphene-is-revolutionizing-sports-gear/">sporting equipment</a> and <a href="http://www.bbc.co.uk/news/uk-england-manchester-36866915">vehicle body panels</a>. Meanwhile graphene’s electrical properties mean it can also <a href="https://www.nature.com/articles/s41467-017-01823-7">enhance battery technologies</a>. </p>
<p>Doesn’t that sound like something an electric car manufacturer might want to look into?</p><img src="https://counter.theconversation.com/content/97476/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Lorch does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Nanotechnology isn’t science fiction – you can find it in the latest TV screens, solar cells and tennis rackets.Mark Lorch, Professor of Science Communication and Chemistry, University of HullLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/359532015-01-07T20:32:26Z2015-01-07T20:32:26ZAre quantum dot TVs – and their toxic ingredients – actually better for the environment?<p>Earlier this week, <a href="https://theconversation.com/the-future-is-bright-the-future-is-quantum-dot-televisions-35765">The Conversation</a> reported that, “The future is bright, the future is … quantum dot televisions.” And judging by the buzz coming from this week’s annual Consumer Electronics Show (<a href="http://www.cesweb.org/">CES</a>) that’s right – the technology is providing manufacturers with a cheap and efficient way of producing the next generation of brilliant, high-definition TV screens.</p>
<p>But the quantum dots in these displays also use materials and technologies – including engineered nanoparticles and the heavy metal cadmium – that have been a magnet for health and environmental concerns. Will the dazzling pictures this technology allow blind us to new health and environmental challenges, or do their benefits outweigh the potential risks?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68360/original/image-20150107-1995-9a8g1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Vials of quantum dots producing vivid colors from violet to deep red.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Quantum_Dots_with_emission_maxima_in_a_10-nm_step_are_being_produced_at_PlasmaChem_in_a_kg_scale.jpg">Antipoff</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Answer’s not black and white</h2>
<p>Quantum dots are a product of the emerging field of nanotechnology. They are made of nanometer-sized particles of a semiconducting material – often cadmium selenide. About 2,000 to 20,000 times smaller than the <a href="http://www.nano.gov/nanotech-101/what/nano-size">width</a> of a single human hair, they’re designed to absorb light of one color and emit it as another color – to fluoresce. This property makes them particularly well-suited for use in products like tablets and TVs that need bright, white, uniform backlights.</p>
<p>There are of course other chemicals, such as phosphor, that fluoresce and are used in consumer products. What is unique about quantum dots is that the color of the emitted light can be modified by simply changing the size of the quantum dot particles. And because this color-shifting is a physical phenomenon, quantum dots far outperform their chemical counterparts in brightness, color and durability.</p>
<p>Unfortunately, the heavy metal cadmium used in the production of many quantum dots is a health and environmental hazard. Under the <a href="http://ec.europa.eu/environment/waste/rohs_eee/legis_en.htm">European Restrictions on Hazardous Substances</a> directive, its use is restricted in electronic equipment. And cadmium and cadmium compounds have been classified as <a href="http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-8.pdf">carcinogenic to humans</a> by the International Agency for Research on Cancer.</p>
<p>On top of this, the potential <a href="http://dx.doi.org/10.1093/toxsci/kfq372">health and environmental impacts</a> of engineered nanoparticles like quantum dots have been raising concerns with toxicologists and regulators for over a decade now. Research has shown that the size, shape and surface properties of some particles influence the harm they are capable of causing in humans and the environment; smaller particles are often more toxic than their larger counterparts. That said, this is an area where scientific understanding is still developing.</p>
<p>Together, these factors would suggest caution is warranted in adopting quantum dot technologies. Yet taken in isolation they are misleading.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68381/original/image-20150107-2005-10h10nk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cadmium selenide nanocrystals on top of a silicon wafer. Each hexagon is 45 microns across.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/argonne/8023118362">Argonne National Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>Quantum dots under glass</h2>
<p>The quantum dots currently being used in TVs are firmly embedded in the screens – usually enclosed behind multiple layers of glass and plastic. As a result, the chances of users being exposed to them during normal operation are pretty much nil.</p>
<p>The situation is potentially different during manufacturing, when there is a chance that someone could be inadvertently exposed to these nanoscopic particles. Scenarios like this have led to agencies like the US National Institute for Occupational Safety and Health taking a close look at safety when <a href="http://www.cdc.gov/niosh/topics/nanotech/">working with nanoparticles</a>. While the potential risks are not negligible, good working practices are effective at reducing or eliminating potentially harmful exposures.</p>
<p>End-of-life disposal raises additional concerns. While the nanoparticles are likely to remain firmly embedded within a trashed TV’s screen, the toxic materials they contain, including cadmium, could well be released into the environment. Cadmium is certainly a health and environmental issue with poorly regulated e-waste disposal and recycling. However, when appropriate procedures are used, exposures should be negligible.</p>
<p>These concerns could be enough to tip the balance against using quantum dots in consumer electronics for some. But they only tell part of the story because these small, bright particles also come with environmental benefits.</p>
<h2>But there are bright benefits</h2>
<p>Quantum dot TVs can be upward of 20% more energy efficient than conventional LED TV screens. And because quantum dots are such an efficient source of bright light, the amount of light-emitting material in these screens (as low a milligram of cadmium in some models) may actually reduce the overall amount of toxic materials used.</p>
<p>These energy and material savings translate into reduced environmental and health impacts. But are they enough to justify the use of a potentially toxic material? </p>
<p>The company <a href="http://www.qdvision.com/">QD Vision</a> has grappled with precisely this question. In developing quantum dots for products like TCL’s <a href="http://www.qdvision.com/content1657">Quantum Dot TV</a> (debuting at CES this year), the company explicitly adopted an approach to responsible development that considered health and environmental impacts. As a result, in 2014 they won the Presidential Green Chemistry Challenge Award from the US Environmental Protection Agency (EPA).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68378/original/image-20150107-1985-1buni27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coal-fired power plant emissions include cadmium.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/derguy/4586888887">Guy Gorek</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Although it seems counter-intuitive, analysis by the company that was made available to the EPA showed QD Vision’s products lead to a net decrease in environmental cadmium releases compared to conventional TVs. Cadmium is one of the pollutants emitted from coal-fired electrical power plants. Because TVs using the company’s quantum dots use substantially less power than their non-quantum counterparts, the combined cadmium in QD Vision TVs and the power plant emissions associated with their use is actally lower than that associated with conventional flat screen TVs. In other words, using cadmium in quantum dots for production of more energy-efficient displays can actually results in a net reduction in cadmium emissions.</p>
<p>This is a neat trick, and it eloquently demonstrates the dangers of jumping to conclusions over risks without seeing the full picture. It does, however, depend on a commitment to responsible innovation and development that considers future health and environmental impacts.</p>
<p>This week at CES, the future of quantum dot televisions is certainly shining bright. With smart approaches to balancing risks and benefits, there’s no reason why this light shouldn’t continue to shine – as long as manufacturers and consumers keep their eye on the big picture.</p>
<hr>
<p><em>This article has been updated to correct the manufacturer of one quantum dot TV that debuted at CES 2015.</em></p><img src="https://counter.theconversation.com/content/35953/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Maynard receives funding from the National Institute of Environmental Health Sciences. He directs the University of Michigan Risk Science Center, which is partly supported through the Gelman Educational Foundation. </span></em></p>Earlier this week, The Conversation reported that, “The future is bright, the future is … quantum dot televisions.” And judging by the buzz coming from this week’s annual Consumer Electronics Show (CES…Andrew Maynard, Director, Risk Science Center, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/357652015-01-06T05:55:56Z2015-01-06T05:55:56ZThe future is bright, the future is … quantum dot televisions<figure><img src="https://images.theconversation.com/files/68208/original/image-20150105-13848-yzva16.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pure, bright, quantum colours.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/argonne/5218967216">Argonne National Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>The Consumer Electronics Show (<a href="http://www.cesweb.org/">CES</a>) has arrived again, the world’s largest consumer electronics and technology exhibition in Las Vegas, where manufacturers will show off the new technologies available in 2015.</p>
<p>Wearables, 3D printers, curved displays and other technology that has graduated from the cutting edge into products available to the consumer – all of them have had their moment in the spotlight at CES. </p>
<p>Korean electronics and display manufacturer LG has set the ball rolling by announcing its <a href="https://theconversation.com/you-dont-need-a-curved-tv-but-4k-is-the-future-21859">4K</a> ultra high-definition television displays (<a href="http://www.techradar.com/news/television/ultra-hd-everything-you-need-to-know-about-4k-tv-1048954">UHDTVs</a>) that use <a href="http://www.trustedreviews.com/opinions/quantum-dots-explained-what-they-are-and-why-they-re-awesome">quantum dot technology</a>, an improved method for producing colour displays.</p>
<h2>What exactly is a quantum dot?</h2>
<p>A significant improvement on existing LCD or LED methods, the technology works by shining blue light through nanocrystals of varying size from two to ten nanometres, which absorb light of one wavelength and emit light of another, very specific wavelength. Each dot emits a different colour depending on its size. A film of quantum dots of a size suitable to produce red and green light is added in front of the screen’s backlight. Generating light via the quantum dots narrows the wavelength of the red and green light produced, meaning less light is caught by the LCD filter. This means better colour rendition and brighter colours.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=327&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=327&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=327&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=411&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=411&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68209/original/image-20150105-13827-1uj9moe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=411&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cadmium-based quantum dot showing pure, highly specific green colour response.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:CdSeqdots.jpg">NASA</a></span>
</figcaption>
</figure>
<p>LG got its announcement in ahead of other manufacturers to try and gain a lead by associating its products with the higher contrast, improved saturation, and impressively wide <a href="http://www.wideformatonline.com/index.php/workshops/colour-management/801-colour-gamut-in-laymans-terms.html">colour gamut</a> (the range of colours a display can reproduce) that quantum dots provide. This makes such displays ideal for viewing high-definition and ultra high-definition content, and for those working in graphic design, photo or film production.</p>
<h2>Upgrading ‘broadcast quality’</h2>
<p>The move towards UHDTV is not just about more pixels and higher-resolution screens. Manufacturers and broadcasters want to create an environment where video and images can be delivered to the public with as high a dynamic range as possible, while remaining economical to manufacture. </p>
<p>And this isn’t in the far future; in fact, the new standards – required for all technologies to become established – have already been sanctioned. The <a href="http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6784055">ITU-rec 2020</a> standard for ultra high-definition television allows for higher frame rates of up to 120 fps, higher bit rates and larger contrast and colour gamuts. </p>
<p>At the moment, content termed “high-definition” is broadcast at 1920 x 1080 pixels with a specific frame rate, range of colour and contrast, allowing consistent reproduction across all compatible displays. But both the broadcast and cinema industries can already produce material that exceeds these standards, there are just no devices yet that can take advantage of the best-quality images possible – there isn’t much point delivering more information than the current displays can handle.</p>
<p>So the use of quantum dots extends the capability of ultra high-definition displays, allowing the delivery of higher dynamic range media to the public in the future. As a bonus, quantum dots are significantly cheaper than other competing high-quality display technologies, such as <a href="http://www.techradar.com/news/television/hdtv/is-oled-dead-the-great-hope-for-tv-tech-is-fading-fast-1265506">OLED</a>, organic light-emitting diodes, which were heralded as the next big thing at previous CES shows, but whose star is already waning.</p>
<p>At the moment quantum dots are being used only combined with other types of backlights, but it’s possible to engineer a method of using them without. In any case, for 2015 and the foreseeable future, the world’s best video and image reproduction for high-definition content will be delivered with quantum dots.</p><img src="https://counter.theconversation.com/content/35765/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laurence Murphy is affiliated with
The Society of motion picture and television engineers, the institution of Engineering and Technology and the British Computing Society</span></em></p>The Consumer Electronics Show (CES) has arrived again, the world’s largest consumer electronics and technology exhibition in Las Vegas, where manufacturers will show off the new technologies available…Laurence Murphy, Senior Lecturer & Researcher in Media Technology, University of SalfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/254912014-04-14T06:10:57Z2014-04-14T06:10:57ZPeptide power: the science behind the 30-second phone charger<figure><img src="https://images.theconversation.com/files/46334/original/j2syf43y-1397453031.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Frustrated by battery drain? A new superfast charger is still a couple of years off ... but it'll be more environmentally friendly than the toxic batteries we use today.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/rpavich/13605581545">rpavich/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>If you’re one of the thousands of <a href="http://forums.androidcentral.com/android-4-1-4-2-4-3-jelly-bean/310053-my-s4-battery-drains-too-fast.html">smartphone users</a> experiencing <a href="https://discussions.apple.com/message/24079637#24079637">battery drain</a>, you’d have been pleased to read that Tel Aviv-based start-up <a href="http://www.store-dot.com/">StoreDot</a> recently unveiled a prototype charger that <a href="http://techcrunch.com/2014/04/07/storedots-bio-organic-battery-tech-can-charge-from-flat-to-full-in-30-seconds/">fully charges</a> a Samsung Galaxy 4 battery in around 30 seconds. </p>
<p>The unit – demonstrated at Microsoft’s <a href="http://blogs.wsj.com/digits/2014/04/07/charge-your-phone-in-30-seconds-an-israeli-firm-says-it-can/">Think Next</a> conference in Tel Aviv – is the size of a small brick, but the company hopes it can <a href="http://blogs.wsj.com/digits/2014/04/07/charge-your-phone-in-30-seconds-an-israeli-firm-says-it-can/">produce and commercialise</a> a more compact model by the end of 2016.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9DhJZAhjbcI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">See for yourself here.</span></figcaption>
</figure>
<p>So what makes this prototype special – and how does it differ to what we use today? To get a good idea of its processes we need to look at it from a quantum perspective.</p>
<h2>Lots of quantum dots</h2>
<p>The new technology, which seems to be a brainchild of <a href="https://www.eng.tau.ac.il/%7Egilr/">Gil Rosenman</a> and colleagues at Tel Aviv University in Israel, is based on biological quantum dots.</p>
<p>A quantum dot is a tiny crystal that is typically made of a <a href="http://en.wikipedia.org/wiki/List_of_semiconductor_materials">semiconductor material</a> such as <a href="http://whatis.techtarget.com/definition/gallium-arsenide-GaAs">gallium arsenide</a>, and is small enough (less than 10 nanometres) to exhibit <a href="http://scitation.aip.org/content/aip/journal/jcp/95/11/10.1063/1.461258">quantum confinement effects</a> (which allow the electronic and optical properties of quantum dots to be controllably tuned).</p>
<p>The concept of using quantum dots for electronics is not new. In the past, electronic devices have focused on using inorganic quantum dots for transistor, solar cell, light emitting diode (LED) and diode laser technologies. </p>
<figure class="align-right zoomable">
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<span class="attribution"><a class="source" href="https://www.flickr.com/photos/emsl/4252247060">EMSL/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>They are the building blocks of modern electronic devices, but these inorganic quantum dots are prepared using highly toxic components such as cadmium, zinc, sulphides and selenides.</p>
<p>Professor Rosenman’s group is working on bio-inspired self-assembly of biological, organic materials – peptides – to achieve the similar tasks as achieved by traditional inorganic semiconductors.</p>
<h2>Going organic</h2>
<p><a href="https://theconversation.com/essendon-faces-a-doping-investigation-but-what-are-peptides-12042">Peptides</a> are short chains of amino acids that play different roles in our body. </p>
<p>In nature, the controlled self-assembly of peptides and proteins is critical for us to perform different tasks. If those processes are disturbed, they can lead to uncontrolled aggregation of peptides which can cause various disorders such as <a href="https://theconversation.com/explainer-what-is-alzheimers-disease-24662">Alzheimer’s disease</a>.</p>
<p>Over the past decade, knowledge gained from nature has enabled scientists to fine-tune the self-assembly of peptides in the laboratory, so peptides can now be artificially modified to self-assemble in different conditions, and function outside a biological organism. </p>
<p>This has led to new applications of peptides in areas such as bio-nanomedicine, bio-nanotechnology, electronics, optics and energy storage.</p>
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<span class="attribution"><a class="source" href="https://www.flickr.com/photos/mikeshaheenphotography/8807354169/">Michael Shaheen/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>StoreDot seems to have manipulated the chemistry of such peptides. This has allowed controllable self-assembly of two peptide molecules into an organic quantum dot of only two nanometres in size. </p>
<p>Since biomimetic self-assembly processes are highly specific, this may lead to an organic quantum dot manufacturing process with high yield and fewer imperfections in the final product. </p>
<p>It is critical to maintain a narrow size range of quantum dots in the final product. This is because different sized quantum dots act differently, but the current manufacturing protocols for inorganic quantum dots tend to suffer from such challenges.</p>
<h2>Beyond chargers</h2>
<p>It is clear that different biological semiconductors can be created to perform a myriad of tasks relevant to electronic devices. These include quick charging batteries and <a href="http://www.store-dot.com/#!our-products/c8c8">visible light emission</a> for displays, on which StoreDot is currently concentrating. </p>
<p>It is not fully clear whether the rapid charging capacity shown by biological semiconductors makes use of the <a href="http://www.princeton.edu/%7Eachaney/tmve/wiki100k/docs/Ferroelectricity.html">ferroelectricity</a> (spontaneous electric polarisation), <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/solids/piezo.html">piezoelectricity</a> (charge acquired through compression or distortion) and/or other properties of self-assembled peptides such as <a href="http://www.nature.com/ncomms/2014/140117/ncomms4109/full/ncomms4109.html">second harmonic generation</a> (where two photons “combine” to create new photons with twice the energy).</p>
<p>Overall, the proof-of-concept demonstration to speed up charging times of current electronic devices is clearly remarkable.</p>
<p>Based on the crystallinity of the peptide-based quantum dots, StoreDot claims that they are stable over multiple cycles of charging – but bio-molecules such as peptides are prone to degrade under standard operating conditions. </p>
<p>Only time will tell whether such bio-based electronic devices will pass the rigorous stability tests expected by consumers across a range of environmental conditions.</p><img src="https://counter.theconversation.com/content/25491/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vipul Bansal receives funding from Australian Research Council through its Discovery, Linkage, and Linkage Infrastructure and Equipment Grant schemes.</span></em></p>If you’re one of the thousands of smartphone users experiencing battery drain, you’d have been pleased to read that Tel Aviv-based start-up StoreDot recently unveiled a prototype charger that fully charges…Vipul Bansal, Associate Professor of Materials Chemistry and Nanobiotechnology and Leader of NanoBiotechnology Research Laboratory (NBRL), RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.