In April 1981, The Washington Post&nbsp;reported that the U.S. supermarket chain, Giant Food Inc., was about to stop marking prices on individual items in its stores in a bid to reduce operating costs. If there was no consumer backlash, the report predicted, the rest of the industry would follow, as it did when the company was the first food retailer to introduce barcode scanners at its checkouts, spurring the spread of that technology across the country.Fast forward 40 years and individually priced items in supermarkets have long been consigned to history, with shelf pricing now the accepted norm. And it has, as Giant Food hoped, reduced operating costs for retailers that can stock as many as 50,000 different product lines. As recently as the 1990s, 7,000 product lines was considered average. Now technology is overhauling shelf labeling anew, and supermarkets will be the likely trailblazers once again.<h2>The beginning of the end for paper labels</h2>Electronic shelf labels (ESL) are connected, low-power &lsquo;e-paper&rsquo; display devices that can replace traditional paper labels and can display text, numbers, icons, lines, barcodes and pictures. They enable retailers to automatically update individual shelf price labels from a central point across multiple stores and branches&mdash;or in certain geographic locations&mdash;at the touch of a button. Comprised of a Cloud platform, access points or gateways, and wirelessly connected shelf labels, pricing commands can be sent from a web-based dashboard to store-located gateways, from which point commands are relayed to the smart labels.According to analyst ABI Research, by the end of last year, 788 million electronic shelf labels (ESL) had been installed globally. The number may seem significant, but with tens of billions of paper labels still on shelves, the technology has yet to make it mainstream, despite not really counting as a &lsquo;new&rsquo; technology. Primitive versions using liquid crystal displays that could display a price but nothing else have been around for some 30 years. There are a number of reasons the technology has yet to hit the big time, including market fragmentation, cost of deployment, concerns over interoperability, security, and a fear of obsolescence. Now this could be about to change.Earlier this year, the Bluetooth Special Interest Group (SIG), announced the release of the <a href="https://www.bluetooth.com/learn-about-bluetooth/use-cases/electronic-shelf-labels/?utm_campaign=2021%20wevolver" rel="noopener noreferrer" target="_blank">new wireless standard for the ESL market</a>, with the goal of making Bluetooth the standard protocol for ESL.&nbsp;The scalable, low-power, secure ESL standard (consisting of ESL Profile and Service specifications) has been developed by a working group comprised of a leading ESL vendor and enabling technology suppliers, and standardizes the process for message transmission between access points and ESLs. To do so it leverages feature enhancements introduced in the Bluetooth Core Specification Version 5.4, including Periodic Advertising with Responses (PAwR) and Encrypted Advertising Data (EAD).In general, PAwR and EAD are intended for one-to-many applications that involve a large number of devices (tags) receiving and transmitting small amounts of data from and to an access point, that accept longer latencies (e.g. 2 seconds) in exchange for extended battery life. Together, they enable connectionless, bidirectional, secure communication with thousands of very low-power end nodes in a star topology, essential in a retail ESL application where many thousands of labels could be required to cover all of the items stocked. For a technical deep dive on ESL, PAwR and EAD see <a href="https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/whats-new-in-bluetooth-v5-4-an-overview?utm_campaign=2021%20wevolver" rel="noopener noreferrer" target="_blank">What&#39;s new in Bluetooth v5.4: An overview</a>.<h2>Dynamic, efficient pricing operations</h2>If the introduction of the standard has the intended effect on the retail industry and ESL becomes widespread, retailers are set to benefit in several ways. Updating paper price labels requires staff to change thousands of tags every week. It&rsquo;s not only a lot of labor to do very little, it also takes time and is prone to error, and inaccurate pricing on shelves even for a short time can cost grocery retailers profit. ESL eliminates the manual process and at the same time enables dynamic pricing strategies allowing retailers to adjust pricing based on stock levels, demand, and market conditions.Standardization is key here to ensure interoperability, security and to allow retailers to have systems that can be installed and easily maintained over a long lifespan. At the same time, Bluetooth can also be leveraged to keep tags updated with the latest firmware, using Over-The-Air Device Firmware Updates from the gateway itself.Moreover, by using Bluetooth as the protocol, some ESL systems can mix and match with other Bluetooth technologies, such as Bluetooth Direction Finding for a quick positioning, enabling staff to quickly and easily identify the specific location of individual product lines across the store. This is particularly beneficial to staff responsible for picking and replenishing stock. Paired with Wi-Fi-connected shelf cameras and Cloud-based AI models, savvy retailers are also remotely monitoring stock to ensure shelves are well stocked and only replenished when necessary.The smart labels can also be used as beacons for marketing to consumers in close proximity via compatible smartphone apps, at the same time allowing retailers to gather insights into customer behavior to provide improved shopping experiences, personalized marketing, and to increase conversion rates in store.<h2>Widescale adoption looms</h2>Nordic Semiconductor, as the market leader in Bluetooth LE, has already introduced the PAwR and EAD features as standard in its qualified Bluetooth 5.4 SoftDevice Controller in the <a href="https://www.nordicsemi.com/Products/Development-software/nRF-Connect-SDK?utm_campaign=2021%20wevolver" rel="noopener noreferrer" target="_blank">nRF Connect SDK</a>, and companies developing ESLs can start working with this technology today thanks to the pre-release reference example (both gateway and tags) now available on request by opening a <a href="https://devzone.nordicsemi.com/support/add?utm_campaign=2021%20wevolver" rel="noopener noreferrer" target="_blank">private ticket on DevZone</a> or by <a href="https://www.nordicsemi.com/About-us/Contact-Us?utm_campaign=2021%20wevolver" rel="noopener noreferrer" target="_blank">contacting Nordic sales</a>.Nordic&rsquo;s SoCs meet the ultra low power requirements of ESLs where the number of tags involved prohibits even infrequent battery changes, while the Flash and RAM allocation ensures they can store the volume of information required to implement a fully-featured ESL system. Both the nRF53 Series and several of the nRF52 Series SoCs also support Direction Finding, enabling optimized order picking and replenishment functionality.The announcement of the standard has provided retailers with the impetus to commit to this technology. ABI Research claims 185 million ESL units were shipped last year, and that by 2028 annual shipments will reach 558 million, with a total installed base of some three billion ESLs. For example, Fortune 500 leading light and U.S. retail behemoth Walmart has entered an agreement to roll out 60 million digital shelf labels across 500 locations over the next 12 to 18 months. Others will follow.<hr>This article was first published on Nordic&#39;s <a href="https://blog.nordicsemi.com/getconnected" target="_blank" rel="nofollow" id="isPasted"></a><a href="https://blog.nordicsemi.com/getconnected?utm_campaign=2021%20wevolver" target="_blank" rel="nofollow">Get Connected Blog</a>. &nbsp;

Electronic shelf labels (ESL) are connected, low-power ‘e-paper’ display devices that can replace traditional paper labels and can display text, numbers, icons, lines, barcodes and pictures. They enable retailers to automatically update individual shelf price labels from a central point across multiple stores and branches—or in certain geographic locations—at the touch of a button.

Bluetooth Electronic Shelf Label standard heralds new retail dawn

In this episode, we discuss research from Harvard that tackles the blurriness and lack of disruption recovery with most holograms which prevents users from having an immersive experience.

Podcast: Key To Unlock Immersive Holograms

In this episode, we discuss research from Harvard that tackles the blurriness and lack of disruption recovery with most holograms which prevents users from having an immersive experience.&nbsp;<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/ea72a4ca-0f64-4727-91ca-0edfe4b226a9?dark=false" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe> <hr><h3 id="isPasted">EPISODE NOTES</h3>(0:50) - <a href="https://www.wevolver.com/article/new-light-sheet-holography-overcomes-the-depth-perception-challenge-in-3d-holograms" target="_blank">New light sheet holography overcomes the depth perception challenge in 3D holograms</a><hr>As always, you can find these and other interesting &amp; impactful engineering articles on Wevolver.com.To learn more about this show, please visit our<a href="https://www.wevolver.com/profile/the.next.byte" target="_blank">&nbsp;shows page</a>. By following the page, you will get automatic updates by email when a new show is published. Be sure to give us a follow and review on<a href="https://podcasts.apple.com/nl/podcast/the-next-byte/id1548255861?l=en" rel="nofollow" target="_blank">&nbsp;Apple</a> podcasts,<a href="https://open.spotify.com/show/6lPPsRtegnivsRUEsQ09R7?si=IPMiah7xT_apJtPjqvXMlA" rel="nofollow" target="_blank">&nbsp;Spotify</a>, and most of your favorite podcast platforms!

20230723-Podcast: Key To Unlock Immersive Holograms

Build your digital signage solution to manage advertising displays with single-board computers.


Building Cost-Effective Advertising Displays with SBCs

Researchers have developed new technology that could usher in the &quot;next-generation&quot; of thinner, higher-resolution and more energy efficient screens and electronic devices. The international team from Nottingham Trent University in the United Kingdom, The Australian National University (ANU) and UNSW Canberra has&nbsp;created nanoparticles called &quot;metasurfaces&quot; that perform better than current displays like LCDs and LEDs. LCDs and LEDs rely on liquid crystal cells to create a display on TVs and other screens. The research team&#39;s metasurfaces are 100 times thinner than liquid crystal cells, offer a tenfold greater resolution and consume 50 per cent less energy. The researchers believe their technology is compatible with modern electronic displays. &quot;We have paved the way to break a technology barrier by replacing the liquid crystal layer in current displays with a metasurface, enabling us to make affordable flat screens liquid crystal-free,&quot; lead researcher Mohsen Rahmani, Professor of Engineering at Nottingham Trent University, said. &quot;The most important metrics of flat panel displays are pixel size and resolution, weight and power consumption. We have addressed each of these with our meta-display concept. &quot;Most importantly, our new technology can lead to a huge reduction of energy consumption - this is excellent news given the number of monitors and TV sets being used in households and businesses every single day. We believe it is time for LCD and LED displays to be phased out in the same way as former cathode ray tube (CRT) TVs over the past ten to 20 years.&quot; Dragomir Neshev, Director of the ARC Centre for Excellence in Transformative Meta-Optical Systems (TMOS) and ANU Professor in Physics, said: &quot;The capability of conventional displays has reached its peak and is unlikely to significantly improve in the future due to multiple limitations. &quot;Today there is a quest for fully solid-state flat display technology with a high-resolution and fast refresh rate. We have designed and developed metasurface pixels that can be ideal for the next-generation display. &quot;Unlike liquid crystals, our pixels do not require polarised lights for functioning, which will halve screens&#39; energy consumption.&quot; Khosro Zangeneh Kamali, a PhD scholar at ANU and the first author of the study, said: &quot;Metasurfaces are proven to exhibit extraordinary optical behaviour. &quot;However, inventing an effective way to control them is still a subject of heavy research. We have proposed electrically programmable silicon metasurfaces, which is a versatile platform for programmable metasurfaces.&quot;&nbsp; Dr Lei Xu, a team member from Nottingham Trent University, said: &quot;There is significant room for further improvements by employing artificial intelligence and machine learning techniques to design and realise even smaller, thinner and more efficient metasurface displays.&quot; Professor Andrey Miroshnichenko, a team member from UNSW Canberra, said: &quot;Our pixels are made of silicon, which offers a long lifespan in contrast with organic materials required for other existing alternatives. Moreover, silicon is widely available, CMOS compatible with mature technology, and cheap to produce.&quot; Professor Miroshnichenko said the team hoped their development could generate a frontier technology in new flat displays with a global market value of about $117 billion in 2020. The work is reported in the journal&nbsp;<a href="https://aus01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fanu.us2.list-manage.com%2Ftrack%2Fclick%3Fu%3D73b3c4bf45063d7aa04d62036%26id%3D7b14896d75%26e%3Da3d1be9eda&data=05%7C01%7Cjames.giggacher%40anu.edu.au%7C3aa53e73db6f43b787c308db15138a89%7Ce37d725cab5c46249ae5f0533e486437%7C0%7C0%7C638126945905851498%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1XgS6ghU7I9hrvV%2BPDdflpeNRGWeOEOf4kRtvlLVivo%3D&reserved=0" target="_blank">Light: Science &amp; Applications</a>. &nbsp;

PhD scholar Khosro Zangeneh. Photo: Jamie Kidston/ANU

Researchers have developed new technology that could usher in the "next-generation" of thinner, higher-resolution and more energy efficient screens and electronic devices.

New tech could create cheaper and thinner flat screens

XTPL developed an unique an totally new approach of printing functional materials with unparallel precision and repeatability. Technology called Ultra-Precise Deposition (UPD) is a nanodispensing method capable to print high density and high viscous materials with the resolution down to 1 &micro;m in feature size and with high ratio of width to height after single pass. For this method material extrusion is controlled by a pressure, which means it is not supported with high electric field. Thanks to this there are no limitation if the substrate is conductive or dielectric.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjY3OTQ0NDk1MzczLUltZy0xLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 736px;" class="fr-fic fr-dib">The combination of unique parameters of the UPD approach opens new possibilities, previously not covered by any other printing methods. First of all, the resolution of the conductive traces can reach 1/1 &micro;m L/S. What is more, similar resolution can be achieved even on complex, 3D topographies. This enables printing high density interconnections through even 90&deg; steps (for example wire-bonding alternative for chip interconnections). Two more unique features were originally tested for conductive structures, but can have a huge benefit for printing other materials like QD ink. These features are micro-bumps deposition and via/micro-cavity filling with the highest repeatability comparing to other printing methods. The biggest needs for QD Color Conversion are ultra-high resolution, possibility of using high solid content inks for high efficiency and repeatability for high homogeneity of the display.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1667944549431-Img-2.jpg" style="width: 764px;" class="fr-fic fr-dib">The precise microdots deposition capability can be used for deposition of micro-bumps for flip chip application. Currently the results presented on the slide below are made using highly-concentrated silver paste (CL85). The dot diameter is around 8 &micro;m, and the dot height is around 800 nm, which gives a relatively high aspect ratio compared to printed electronics techniques, like inkjet or EHD, and competitive repeatability. The cross-section analysis of the dots shows parabolic geometry, which, for example, simplifies the deposition of subsequent layers without the risk of cracks. A photo of Albert Einstein made of hundreds of thousands of 8 &micro;m micro-bumps presents also the stability of the process over the time.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1667944610806-Img-3.jpg" style="width: 750px;" class="fr-fic fr-dib">The ability of UPD to extrude ink with femtoliter precision allows not only to print microdots but also to fill microcavities. This feature may help manufacture high-resolution multilayers or through silicon via interconnections. To fill a microcavity, one has to precisely position the printing nozzle and dispense a certain amount of material. In the slide below you can see microcavity with a depth of 10 &mu;m and a diameter of 25 &mu;m, which we uniformly fill with a silver paste (85 wt.% of solid content). Similar capabilities of precise microcavity filling can be used in deposition of QD material into structures like photoresist windows or nanorings to significantly increase color conversion efficiency (CCE). Compared to other digital additive manufacturing techniques like inkjet and EHD, UPD technology allows to fill the structures with high uniformity and repeatability with use of inks with higher concentration of QDs. Combination of unique capabilities of the UPD printing method provides a solution for efficient fabrication of QD color conversion for next generation Micro-LED displays.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1667944645211-Img-4.jpg" style="width: 751px;" class="fr-fic fr-dib">

A unique new approach of printing functional materials with unparallel precision and repeatability. Technology called Ultra-Precise Deposition (UPD) is a nanodispensing method capable to print high density and high viscous materials with the resolution down to 1 µm in feature size and with high ratio of width to height after single pass. For this method material extrusion is controlled by a pressure, which means it is not supported with high electric field. Thanks to this there are no limitation if the substrate is conductive or dielectric.

Ultra-Precise Deposition for the Fabrication of Next-Generation MicroLED and QD-LED Displays

Building on their groundbreaking work for <a href="file:///Users/cmsj/Downloads/for%20any%20display%20or%20VR%20application.%2010:42:28%20You%20need%20to%20have%203%20colors,%20red,%20green,%20and%20blue,%20so%20so%20very%20important%20to%20have%20them,%20and%20also%20very%20important%20to%20have%20a%20stable%20emission.%2010:42:39%20So%20that,%20you%20know,%20when%20your%20display%20becomes%20brighter.%2010:42:42%20You%20have%20seen%20the%20same%20color%20right%3f%20if%20it's%20not%20stable%20when%20you%20increase%20the%20brightness,%20then%20the%20green%20becomes%20the%20bluish,%20red%20of%20it%20becomes%20greenish,%20so%20it's%20not%20a%20high%20quality%20display.%2010:42:57%20And%20so%20what's%20really%20important%20here%20is%20a%20way%20to%20make%20them%20very,%20very%20stable%20for%20such%20a%20small%20size%20LEDs,%20and%20be%20able%20to%20grow%20them%20directly%20on%20the%20silicon%20wave,%20which%20is%20really%20really%20important%20for%20the%20future%20manufacturing%2010:43:10%20integration%20process" target="_blank">highly-efficient red micro light emitting diodes (LEDs),&nbsp;</a>Prof. Zetian Mi&rsquo;s research team have now achieved a new approach for the design, fabrication, and integration of high-performance green micro-LEDs on silicon. These highly stable micro-LEDs are important for a broad range of applications in on-chip optical communication, including emerging augmented reality/mixed reality devices, and ultrahigh-resolution full-color displays.&ldquo;It&rsquo;s very important to have a stable emission of all three colors &ndash; red, green, and blue &ndash; to achieve a high-quality display,&rdquo; Mi said. &ldquo;And it&rsquo;s especially important to grow these small, stable LEDs directly on the silicon wafer for the future manufacturing and integration process.&rdquo;LEDs, which are typically stacks of semiconductor thin films, have already revolutionized the lighting and display world. They are far superior in efficiency, stability, and device volume compared to traditional devices, such as incandescent light bulbs and cathode tubes.However, LEDs have many limitations when it comes to supporting virtual and augmented reality, as well as other emerging optoelectronic applications. These new applications demand micrometer or smaller LEDs that are highly stable, highly efficient, have ultralow power consumption, and can support full-color emission and brightness. In other words, they need to be one million times smaller than conventional broad area devices without sacrificing their quality.Mi&rsquo;s team recently succeeded in creating red micro-LEDs that are nearly three orders of magnitude smaller in surface area than previously reported devices while exhibiting external quantum efficiency of ~1.2%, but green micro-LEDs come with their own challenges.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1666235664577-pandey-malhotra-1024x332.jpg" style="width: 766px;" class="fr-fic fr-dib">Mi&rsquo;s red micro-LED research: (L) Postdoctoral researcher Ayush Pandey helped plan the parameters of the nanowires for growth in the MBE system, and then fabricated the actual LEDs in the Lurie Nanofabrication Facility. (R) ECE doctoral student Yakshita Malhotra helped plan the parameters and then grow the nanowire crystals using the MBE system in Prof. Mi&rsquo;s lab.&nbsp;&ldquo;You can make very efficient large-area blue LEDs and large area red LEDs, but it is extremely difficult to make very efficient large area green LEDs. This is called the &lsquo;Green Gap,&rsquo;&rdquo; Mi said. &ldquo;But shrinking a device&rsquo;s dimension to about one micrometer is extremely challenging whether it&rsquo;s green or red.&rdquo;In addition, it&rsquo;s important for these micro- and submicron-LEDs to be grown on silicon, instead of the traditional sapphire wafer. Silicon wafers improve the manufacturing process, allow for improved scalability and integration with small electronics, and are more cost-efficient. Specifically, they&rsquo;re more suitable for integration with complementary metal-oxide-semiconductor (CMOS) electronics, which would pave the way for much more powerful photonic circuits. But using silicon also creates a mismatch in the lattice parameter, for the crystal structure is different.To address these challenges, Mi&rsquo;s team developed III-nitride submicron-scale green micro-LEDs using arrays of nanowires, each of which is only 100-200 nm in diameter and tens of nanometers apart.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1666235687610-GreenLED-content.jpg" style="width: 766px;" class="fr-fic fr-dib">Yixin Xiao, center, a PhD student, and Yuanpeng Wu, a postdoctoral research fellow, both in ECE, and members of Professor Zetian Mi&rsquo;s research group, working in the molecular beam epitaxy lab in the EECS Building on the North Campus of the University of Michigan. In the lab they are growing Indium gallium nitride (InGaN) nanowire micro-LEDs using molecular beam epitaxy. Photo: Brenda Ahearn/College of Engineering&nbsp;&ldquo;We use the nanowire structure to filter out the threading dislocations caused by lattice mismatch between the nitride materials and the silicon substrate,&rdquo; said Yuanpeng Wu, a postdoc in Mi&rsquo;s group and first author on the paper.The result is the first high-performance, highly stable green micro-LEDs grown on silicon. They plan to apply the same sort of process for blue micro-LEDs.&ldquo;The approach we developed for green readily applies to blue,&rdquo; Mi said. &ldquo;The next step is integrating directly on the silicon wafer without transferring, which would be a huge improvement for manufacturing.&rdquo;With red, green, and blue micro-LEDs, the future of next-generation display technology begins.The research is detailed in&nbsp;<a href="https://trebuchet.public.springernature.app/get_content/f868891b-9374-4648-bd01-13235847ca08" target="_blank">&ldquo;InGaN micro-light-emitting diodes monolithically grown on Si: achieving ultra-stable operation through polarization and strain engineering&rdquo;</a> by Yuanpeng Wu, Yixin Xiao, Ishtiaque Navid, Kai Sun, Yakshita Malhotra, Ping Wang, Ding Wang, Yuanxiang Xu, Ayush Pandey, Maddaka Reddeppa, Walter Shin, Jiangnan Liu, Jungwook Min, and Zetian Mi,&nbsp;Light Science &amp; Application,&nbsp;October 2022.Fabrication work was accomplished in the&nbsp;<a href="https://lnf.umich.edu/" target="_blank">Lurie Nanofabrication Facility,</a> and technical support was provided by the&nbsp;<a href="https://mc2.engin.umich.edu/" target="_blank">Michigan Center for Materials Characterization</a>.Some intellectual property related to GaN-based nanowires was licensed to NS Nanotech Inc., which was co-founded by Mi. The University of Michigan and Mi have a financial interest in NS Nanotech, Inc.

Yuanpeng Wu, right, a postdoctoral research fellow, and Yixin Xiao, a PhD student, both in ECE, and members of Professor Zetian Mi’s research group, working in the molecular beam epitaxy lab in the EECS Building on the North Campus of the University of Michigan. In the lab they are growing Indium gallium nitride (InGaN) nanowire micro-LEDs using molecular beam epitaxy. Photo: Brenda Ahearn/College of Engineering

Prof. Zetian Mi’s team are the first to achieve high-performance, highly stable green micro-LEDs with dimensions less than 1 micrometer on silicon, which can support ultrahigh-resolution full-color displays and other applications.

Breakthrough in green micro-LEDs for augmented-mixed reality devices

As anyone who has recently tried out an augmented reality headset knows, the technology is not yet ready to be part of our everyday lives. Researchers have been working to perfect high-performing augmented reality (AR) glasses, but there are a number of challenges. One major problem with conventional AR glasses is that there is a tradeoff in terms of quality and brightness between the external scene you actually see and the contextual information you also want to visualize. Early solutions like Google Glass used multiple bulky optical components that were partially reflective and partially transmissive to mix the real-world and contextual scenes, with the result of a dimmed and distorted vision of both scenes.More recent AR head-mounted-display eyeglasses have been patterned with diffractive gratings (fine grooves) with wavelength-sized spacing that deflect contextual information from a miniprojector beside the glasses to the viewer&rsquo;s eye. But these eyeglasses still dim and distort the external scene because real-world light passing through the glass inevitably gets scattered and dispersed by the gratings. The distortions get worse when several sets of overlapping gratings must be used to handle multiple distinct colors from the miniprojector. AR glasses that perfectly blend the external environment and contextual information for the human eye would be highly useful for many applications. As a head-up display, the technology could give navigation instructions to someone driving a car or feed data from sensors to the pilot flying a plane without requiring them to look away from their windshields. As a head-mounted display, the technology could enable surgeons and soldiers to view information related to their tasks at hand with unprecedented ease and efficiency.The glass needs to not only be highly transparent over almost the entire visible spectrum, allowing for unattenuated and undistorted vision of the outside world, but also to function as a highly efficient lens that focuses light from a miniprojector into the human eye to form a visual context accompanying the external real-world scene.<h2>Study demonstrates new kind of wavelength-selective, wavefront-shaping glass<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664972880052-multifunctional-nonlocal-metasurface-enabled-ar-demonstration.jpg" style="width: 766px;" class="fr-fic fr-dib">Illustration showing the operation of an augmented reality headset with multifunctional nonlocal metasurfaces as optical see-through lenses. Credit: Nanfang Yu, Stephanie Malek, Adam Overvig/Columbia Engineering&nbsp;</h2><section id="isPasted">Researchers at <a href="http://engineering.columbia.edu/" target="_blank">Columbia Engineering</a> report that they have now invented just this kind of glass. Led by <a href="https://www.engineering.columbia.edu/faculty/nanfang-yu" target="_blank">Nanfang Yu</a>, associate professor of <a href="https://www.apam.columbia.edu/" target="_blank">applied physics and applied mathematics</a>, the team has created a flat optical device that focuses only a few selected narrowband colors of light while remaining transparent to nonselected light over the vast majority of the spectrum. The <a href="https://www.nature.com/articles/s41377-022-00905-6" target="_blank">paper</a> was published online August 8, 2022, by Light: Science &amp; Applications.</section><section><blockquote>We&rsquo;ve built a very cool flat optical device that appears entirely transparent&mdash;like a simple piece of glass&mdash;until you shine a beam of light with the correct wavelength onto it, when the device suddenly turns into a lens. To me this is optical magic.<footer>NANFANG YUASSOCIATE PROFESSOR OF APPLIED PHYSICS AND APPLIED MATHEMATICS</footer></blockquote></section><section>&ldquo;We&rsquo;ve built a very cool flat optical device that appears entirely transparent&mdash;like a simple piece of glass&mdash;until you shine a beam of light with the correct wavelength onto it, when the device suddenly turns into a lens,&rdquo; said Yu, a leader in nanophotonics research. &ldquo;To me this is optical magic.&rdquo;<h2>Metasurfaces</h2></section><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664972967719-flat-glass-visual.jpg" style="width: 766px;" class="fr-fic fr-dib">Top row: (Left) Illustration showing the operation of a wavelength-selective metalens, with &ldquo;green&rdquo; light being focused, while the other colors are passed without distortion. (Middle) Optical image of a wavelength-selective metalens composed of rectangular apertures etched into a silicon thin film. (Right) Scanning electron microscope (SEM) images of the metalens at its center and edge.&nbsp; Bottom row: A series of two-dimensional (2D) far-field scans shows that focusing is most efficient at the center of the resonance, l= 1590 nm, with the focusing efficiency dropping at the two shoulders of the resonance, l= 1575 nm and 1600 nm, and that the focal spots become almost undetectable at wavelengths tens of nanometers away from the center of the resonance. Credit: Nanfang Yu, Stephanie Malek, Adam Overvig/Columbia Engineering&nbsp;<a href="https://www.apam.columbia.edu/faculty/nanfang-yu" target="_blank">Yu&rsquo;s group</a> develops flat optical devices based on metasurfaces&mdash;ultra-thin optical components&mdash;to control light propagation in free space and in optical waveguides. Metasurfaces are made of two-dimensional (2D) arrays of designer scatterers, called &ldquo;optical antennas&rdquo; &mdash; a tiny version of radio antennas that have nanometer-scale dimensions. The key feature of metasurfaces is that the optical scatterers are all different optically. The light they scatter can have different amplitude, phase, or polarization, so that metasurfaces can introduce a spatially varying optical response that can control light in extremely flexible ways. As a result, metasurfaces make it possible to realize functionalities that conventionally require 3D optical components or devices with a much larger footprint, such as focusing or steering light beams, or switching optical signals on integrated photonic chips.<h2>Nonlocal metasurfaces</h2>Yu&rsquo;s team invented a &ldquo;nonlocal metasurface&rdquo; that can manipulate light waves in distinct ways at distinct targeted wavelengths, while leaving light at untargeted wavelengths unaffected. The new devices exert both spatial and spectral control over light by selecting a color (spectral) and focusing it (spatial) not just at a single wavelength but also independently at multiple different wavelengths. For example, one demonstrated device functions both as a converging lens that focuses light at one color, and as a concave lens that disperses light at a second color, while staying transparent, like an unpatterned slab of glass, when illuminated with light at colors over the rest of the spectrum.<h2>Breaking symmetry to radiate light and shape its wavefront</h2><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664972997562-flat-glass-visual2.jpg" style="width: 766px;" class="fr-fic fr-dib">Left: Illustration showing the operation of a three-function metalens doublet. The doublet is able to generate three distinct focal patterns (two focal lines orthogonal to each other and a star-shaped focal spot) at three different wavelengths, while staying transparent at other wavelengths. The doublet is composed of a quasi-radial metalens as a diverging element and a dual-function cylindrical metalens as a converging element. Middle: Optical images of the quasi-radial metalens and the dual-function cylindrical metalens. Right: SEM images showing the corners of the quasi-radial metalens and the dual-function cylindrical metalens. Credit: Nanfang Yu, Stephanie Malek, Adam Overvig/Columbia Engineering&nbsp;These new devices originated from theoretical explorations by Adam Overvig, a former PhD student in Yu&rsquo;s group and co-author of the study, into how to manipulate symmetry in photonic crystal (PhC) slabs, such as a 2D periodic structure that is a square array of square holes defined in a thin film of silicon. PhC slabs are known to support a set of modes, the frequencies or colors of which are determined by the geometry of the slab (e.g., periodicity of the array and size of the holes). The modes are essentially a sheet of light that is spatially extended (nonlocal) along the slab but otherwise confined in the direction normal to the slab.Introducing a symmetry-breaking perturbation to an otherwise structurally repetitive PhC slab, such as simply by deforming square holes of the PhC into rectangular ones, lowers the degree of symmetry of the PhC so that the modes are no longer confined to the slab: they can be excited by shining a beam of light from free space with the correct color and can also radiate back into free space.Significantly, instead of applying a uniform perturbation over the entire PhC slab, the researchers spatially varied the perturbation, orienting the rectangular holes along different directions over the device. In this way, the surface emission from the device could have a molded wavefront in relation to the pattern of the orientation angles of the rectangles.<h2>First to make lenses that focus light of just the desired color</h2>&ldquo;This is the first time that anyone has experimentally demonstrated wavelength-selective, wavefront-shaping optical devices using an approach that is based on symmetry-breaking perturbations,&rdquo; explained Stephanie Malek, a doctoral student in Yu&rsquo;s group who was lead author of the study. &ldquo;By carefully choosing the initial PhC geometry, we can achieve wavelength selectivity, and by tailoring the orientations of the perturbation applied to the PhC, we can sculpt the wavefront of the selected color of light. This means that we can make lenses that focus light of only the selected color.&rdquo;<h2>The most highly multifunctional and multicolor metasurface yet</h2>The team demonstrated a multifunctional device that shapes the optical wavefronts independently at four distinct wavelengths but acts as a transparent substrate at other nonselected wavelengths. This makes it the most highly multifunctional and multicolor metasurface that has been demonstrated so far, and also suggests that in the future full-color AR displays can be made by independently controlling a few colors of virtual information.<h2>AR applications</h2>These new wavelength-selective, wavefront-shaping &ldquo;nonlocal&rdquo; metasurfaces offer a promising solution for AR technologies, including head-up displays on the front windshield of cars. The optical see-through lens can reflect contextual information to the viewer&rsquo;s eye at selected narrow-band wavelengths of the miniprojector while also allowing an unobstructed, undimmed, broadband view of the real world. And, because the wavelength-selective metasurface lenses are thinner than a human hair, they are well-suited to developing AR goggles that look and feel like comfortable and fashionable eyeglasses.<h2>Quantum optics</h2><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664973027349-flat-glass-visual3.jpg" style="width: 766px;" class="fr-fic fr-dib">A series of 2D far-field scans showing the three focal patterns at l=1,424 nm, 1,492 nm, and 1,626 nm and minimal wavefront shaping over the rest of the spectrum. Credit: Nanfang Yu, Stephanie Malek, Adam Overvig/Columbia Engineering&nbsp;Yu&rsquo;s flat metasurfaces can also be used to substantially reduce the complexity of quantum optics setups that manipulate ultracold atoms. Because multiple laser beams at distinct wavelengths have to be independently controlled for cooling, trapping, and monitoring cold atoms, these setups can become massive. This complexity has made it difficult for researchers to widely adopt cold atoms for use in atomic clocks, quantum simulations and computations. Now, instead of building several ports around the vacuum chamber for the cold atoms, each with their unique beam-shaping optical components, a single metasurface device can be used to simultaneously shape the multiple laser beams used in the experiment.<h2>What&rsquo;s next: demonstrating the concept in visible spectrum range</h2>The devices in this study simultaneously and independently control the wavefronts of several near-infrared beams using nanostructured silicon thin films. The team plans next to demonstrate the concept in the visible spectral range, to fully control the wavefronts of three narrowband visible laser beams using a device platform featuring low absorption loss in the visible, such as thin-film silicon nitride and titanium dioxide. They are also exploring the scalability of the wavelength-selective metasurface platform by including more than two perturbations into a single metasurface and by stacking more than two metasurfaces into a compound device.Device fabrication was carried out at the <a href="http://cni.columbia.edu/" target="_blank">Columbia Nano Initiative</a> cleanroom, and at the <a href="https://asrc.gc.cuny.edu/nanofab/" target="_blank">Advanced Science Research Center NanoFabrication Facility</a> at the Graduate Center of the City University of New York.

Columbia engineers invent a flat lens that exclusively focuses light of a selected color—it appears entirely transparent until they shine a beam of light with the correct wavelength onto it, when the glass turns into a lens.

Optical Magic: New Flat Glass Enables Optimal Visual Quality for Augmented Reality Goggles

The researchers, from the Department&#39;s <a href="https://ee.eng.cam.ac.uk/" target="_blank">Electrical Engineering division</a>, designed the <a href="https://www.nature.com/articles/s41467-022-31853-9" target="_blank">next-generation smart lighting system</a> using a combination of nanotechnology, colour science, advanced computational methods, electronics and a unique fabrication process.They found that by using more than the three primary lighting colours used in typical LEDs, they were able to reproduce daylight more accurately. Early tests of the new design showed excellent colour rendering, a wider operating range than current smart lighting technology, and wider spectrum of white light customisation.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664766264335-quantum-dots-copy_0.jpg" style="width: 766px;" class="fr-fic fr-dib">As the availability and characteristics of ambient light are connected with wellbeing, the widespread availability of smart lighting systems can have a positive effect on human health since these systems can respond to individual mood. Smart lighting can also respond to circadian rhythms, which regulate the daily sleep-wake cycle, so that light is reddish-white in the morning and evening, and bluish-white during the day.When a room has sufficient natural or artificial light, good glare control, and views of the outdoors, it is said to have good levels of visual comfort. In indoor environments under artificial light, visual comfort depends on how accurately colours are rendered. Since the colour of objects is determined by illumination, smart white lighting needs to be able to accurately express the colour of surrounding objects. Current technology achieves this by using three different colours of light simultaneously.Quantum dots have been studied and developed as light sources since the 1990s, due to their high colour tunability and colour purity. Due their unique optoelectronic properties, they show excellent colour performance in both wide colour controllability and high colour rendering capability.The Cambridge researchers developed an architecture for quantum-dot light-emitting diodes (QD-LED) based next-generation smart white lighting. They combined system-level colour optimisation, device-level optoelectronic simulation, and material-level parameter extraction.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664766274411-3d.jpeg" style="width: 766px;" class="fr-fic fr-dib">TEM images of the red, green, cyan, and blue QDs used for device fabrication and charge transport simulation.The researchers produced a computational design framework from a colour optimisation algorithm used for neural networks in machine learning, together with a new method for charge transport and light emission modelling.The QD-LED system uses multiple primary colours &ndash; beyond the commonly used red, green and blue &ndash; to more accurately mimic white light. By choosing quantum dots of a specific size &ndash; between three and 30 nanometres in diameter &ndash; the researchers were able to overcome some of the practical limitations of LEDs and achieve the emission wavelengths they needed to test their predictions.The team then validated their design by creating a new device architecture of QD-LED based white lighting. The test showed excellent colour rendering, a wider operating range than current technology, and a wide spectrum of white light shade customisation.The Cambridge-developed QD-LED system showed a correlated colour temperature (CCT) range from 2243K (reddish) to 9207K (bright midday sun), compared with current LED-based smart lights which have a CCT between 2200K and 6500K. The colour rendering index (CRI) &ndash; a measure of colours illuminated by the light in comparison to daylight (CRI=100) &ndash; of the QD-LED system was 97, compared to current smart bulb ranges, which are between 80 and 91.The design could pave the way to more efficient, more accurate smart lighting. In an LED smart bulb, the three LEDs must be controlled individually to achieve a given colour. In the QD-LED system, all the quantum dots are driven by a single common control voltage to achieve the full colour temperature range.&ldquo;This is a world-first: a fully optimised, high-performance quantum-dot-based smart white lighting system,&rdquo; said <a href="http://www.eng.cam.ac.uk/profiles/jmk71" target="_blank">Professor Jong Min Kim</a> from Cambridge&rsquo;s Department of Engineering, who co-led the research. &ldquo;This is the first milestone toward the full exploitation of quantum-dot-based smart white lighting for daily applications.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1664766304130-4l.jpeg" style="width: 766px;" class="fr-fic fr-dib">Voltage-dependent chromaticity variations of the fabricated lighting systems with identical (green dots) and optimised (blue dots) emission pattern widths.&ldquo;The ability to better reproduce daylight through its varying colour spectrum dynamically in a single light is what we aimed for,&rdquo; said <a href="http://www.eng.cam.ac.uk/profiles/gaja1" target="_blank">Professor Gehan Amaratunga</a>, who co-led the research. &ldquo;We achieved it in a new way through using quantum dots. This research opens the way for a wide variety of new human responsive lighting environments.&rdquo;The structure of the QD-LED white lighting developed by the Cambridge team is scalable to large area lighting surfaces, as it is made with a printing process and its control and drive is similar to that in a display. With standard point source LEDs requiring individual control this is a more complex task.

Researchers have designed smart, colour-controllable white light devices from quantum dots, tiny semiconductors just a few billionths of a metre in size, which are more efficient and have better colour saturation than standard LEDs, and can dynamically reproduce daylight conditions in a single light

Quantum Dots That Produce Smart White Lighting For Daylight

The first slide shows the battery gap- Ahmed has collected data by year showing that power demand of phones far exceeds the power supply level of batteries, creating a &quot;battery gap&quot; which widens each year as more power-hungry features are added whilst battery technologies imporves only incrementally. Some 70% of power consumption of a mobile phone or tablet is by the display, showing its outsize importance in shrinking this gap. The second slide shows the improvements in the efficiency (lm/W) of &#39;released&#39; OLED devices per year. The OLED efficiency has clearly plateaued in produced or released products. The backdot represents the projected potential of microLEDs, showing how the microLED technology can be a game changer. The third slide shows that there is a gap between EQE of laboratory OLEDs and that of released products. The origins are not clear but likely involve trade-offs neccessary in production and trade-offs between lifetime stability and EQE. The four side compares the efficiency of GaNw LEDs at various wavelenghts vs organic LEDs (from previous slides). It shows that GaN LEDs offer dramatically higher EQE levels compared to OLEDs at all wavelenghts except red. Indeed, there is a red efficiency gap in GaN microLED technology, the filling of which is the subject of intense global R&amp;D This charts clearly demonstrate that while OLED technology seems to have plateaued and thus will not likely ever overcome the Battery Gap, the emerging microLED technology offers high promise to do us. Of course development and manufacturing of microLEDs involves other challenges such as rapid transfer as well as high-yield production which we will disucss elsewhere To learn more about microLED technologies, join the world&#39;s first ever specialist technology on the topic. Check out the world-class agenda at www.TechBlick.com/microLEDs <a data-attribute-index="2" href="https://www.linkedin.com/feed/hashtag/?keywords=microled&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#microled</a> <a data-attribute-index="3" href="https://www.linkedin.com/feed/hashtag/?keywords=miniled&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#miniled</a> <a data-attribute-index="4" href="https://www.linkedin.com/feed/hashtag/?keywords=qd&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#qd</a> <a data-attribute-index="5" href="https://www.linkedin.com/feed/hashtag/?keywords=quantumdot&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#quantumdot</a> <a data-attribute-index="6" href="https://www.linkedin.com/feed/hashtag/?keywords=displaytechnology&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#displaytechnology</a> <a data-attribute-index="7" href="https://www.linkedin.com/feed/hashtag/?keywords=displays&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#displays</a> <a data-attribute-index="8" href="https://www.linkedin.com/feed/hashtag/?keywords=oled&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#oled</a> <a data-attribute-index="9" href="https://www.linkedin.com/feed/hashtag/?keywords=gan&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#GaN</a> <a data-attribute-index="10" href="https://www.linkedin.com/feed/hashtag/?keywords=led&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6966071204499619841" target="_blank">#led</a>&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1662557033458-1.png" style="width: 687px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1662557044006-2.png" style="width: 690px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1662557052709-3.png" style="width: 658px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1662557064178-4.png" style="width: 729px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1662557072042-5.png" style="width: 715px;" class="fr-fic fr-dib">

Why can microLED technology can help narrow the energy gap in electronic devices? The first slide shows the battery gap- Ahmed (Intel) has collected data by year showing that power demand of phones far exceeds the power supply level of batteries, creating a "battery gap" which ...

Why can microLED technology help narrow the energy gap in electronic devices?

Komori has recently achieved excellent results with gravure printing of microbumps on wafers for microLEDs. The results will be unveiled at TechBlick&#39;s upcoming microLED event on 30 Nov-1 Dec 2022: www.TechBlick.com/microLEDsAs seen in the slides below, gravure printing can print microbumps printed using flux paste, achieving a printing precision of 5 &micro;m within a range of 300 mm. The first slides show the precision of the printing position on a wafer. In particular, it compares it with screen printing, showing how gravure printing advances the fine feature printing capability w.r.t screen printing (+/-10 um although screen printing too can and will also advance)As shown in slide two, the minimum diameter that can be printed with SAC (Sn, Ag, Cu) solder paste is 6 &mu;m and the distance between the centers of the bumps is 30 &mu;m. Reflow has been successful with a minimum diameter of 10 &micro;m. This way for example, a microLED die in the size of 30um by 50 or 80um can be supported.Furthermore, as shown in slide three, this technique also offers the possibility to control the thickness by printing several diameters. The smaller the bump diameter, the higher the aspect ratio.This are very nice results, showing the viability of gravure printing technique for microbumps. This technology can support current and near-term generations of microLEDs but will it evolve as microLED dies further shrink in the longer term?Join Komori and other members of the community to learn about all aspects of microLEDs from GaN microLED technology to transfer and tiling technology to bumping and color conversion technology and beyond. You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more &nbsp;<a href="//www.TechBlick.com/microLEDs" rel="noopener noreferrer" target="_blank">www.TechBlick.com/microLEDs</a> Read more at&nbsp;<a href="https://www.techblick.com/post/gravure-wafer-printing-to-support-6um-microbumps-in-microled-displays" id="isPasted" rel="noopener noreferrer" target="_blank">https://www.techblick.com/post/gravure-wafer-printing-to-support-6um-microbumps-in-microled-displays</a><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU1MDE5NDU4LTEucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 727px;" class="fr-fic fr-dib"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU1MDM3MDEwLTIucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 615px;" class="fr-fic fr-dib"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU1MDQ4Mzc3LTMucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 626px;" class="fr-fic fr-dib"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU1MDU4MjkyLTQucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 662px;" class="fr-fic fr-dib">

As microLEDs inevitably shrink in size, the micro-bumping requirements for the microLED dies becomes more challenging. Direct wafer-based printing based on gravure offset techniques offers a promising solution in this regard. Indeed, this is another field where printed electronics can play a role. 

Gravure print microbumps on wafers for ever-shrinking microLED dies

Inkjet is the common technology investigated for such a purpose. As shown below by Prof.<a data-attribute-index="0" data-entity-hovercard-id="urn:li:fs_miniProfile:ACoAAA2DwbsBjBmPizVSJiBZbtld4e3Uf98t1n4" data-entity-type="MINI_PROFILE" href="https://www.linkedin.com/in/ACoAAA2DwbsBjBmPizVSJiBZbtld4e3Uf98t1n4" id="isPasted" target="_blank">Armin Wedel</a>, however, its 4pL droplet is too large, allowing at best a 40um pixel and not able to reach even 850 dpi Electrohydrodynamic printing (EHD) can however address this issue. In EHD, the droplets are pulled out by an electric field from a nozzle which sits close (50um or so) to the surface and thus requires a good printing facility. As shown below, the droplet volume is only 0.5pL, enabling 1-10um pixels in the lab and 15um reproducibly. This will enable one to achieve 850ppi and 1000ppi! Slide 2 shows an example of a QD color filter (QD-CF) for a microLED display deposited using EHDJet. Here, 15um pitch is reported, achieving 1000ppi. The roadmap will be to evolve the technology towards even 2000ppi! These are excellent advacements of the art and technology, paving the way for the development of high-PPI microLED technology Of course, EHDJet is a relatively new technology. It is mainly single head and slow, although multi-head print heads are emerging. Nonetheless, it is an elegant solution for depositing color filters on high-PPI microLED displays. To learn the latest about these technologies joint TechBlick&#39;s specialist event on microLEDs and Quantum Dots where Prof. Wedel will also present:&nbsp;<a data-attribute-index="9" href="http://www.techblick.com/microLED" target="_blank">www.TechBlick.com/microLED</a> You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more&nbsp; Read more at&nbsp;<a href="https://www.techblick.com/post/high-ppi-rgb-microleds-printed-electronics-and-quantum-dots" id="isPasted" rel="noopener noreferrer" target="_blank">https://www.techblick.com/post/high-ppi-rgb-microleds-printed-electronics-and-quantum-dots</a><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU0ODAzMDUxLTEucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 762px;" class="fr-fic fr-dib"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU0ODE0OTMwLTIucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 702px;" class="fr-fic fr-dib"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjYyNTU0ODMyNTc0LTMucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 703px;" class="fr-fic fr-dib">

The three themes are closely linked since QDs can be digitally printed as color conversation materials atop blue microLEDs to enable wide color gamut RGB uLED displays without requiring a separate transfer step for each color.. This is an important technology as it simplifies the manufacturing step for microLED and thus removing a major hinderence. 

High-PPI RGB microLEDs, printed electronics, and quantum dots?

Phosphors or QDs for color conversion in LCD and microLED ? Which will win? This is an interesting and evolving technology space to watch. <a data-attribute-index="0" data-entity-hovercard-id="urn:li:fs_miniProfile:ACoAAAIvgBYBfQjVeeqd_uc7uiIftwRomB9sV5I" data-entity-type="MINI_PROFILE" href="https://www.linkedin.com/in/ACoAAAIvgBYBfQjVeeqd_uc7uiIftwRomB9sV5I" id="isPasted" target="_blank">James E. Murphy</a> et al from&nbsp;<a data-attribute-index="2" data-entity-hovercard-id="urn:li:fs_miniCompany:7364" data-entity-type="MINI_COMPANY" href="https://www.linkedin.com/company/geresearch/" target="_blank">GE Research</a> have developed best-in class narrowband red and green phosphors, and are now evolving the technology towards microLEDs and on-chip integration The red KSF phosphor is an excellent narrow band color converter for wide color gamut displays. It emits 5 peaks, each of which exhibits&nbsp;an ultra narrow 5-nm FWHM.&nbsp;The main peak is centred around 631nm. It is a stable material under high light flux and high temperature conditions. Indeed, it can be on-chip integrated as a direct replacement for existing yellow phosphors.&nbsp;It is a major commercial success with &gt;19 licensees and &gt;40 BILLION (and growing) KFS-containing LEDs sold worldwide into the display industry. As the slide below, presented at&nbsp;<a data-attribute-index="4" data-entity-hovercard-id="urn:li:fs_miniCompany:71510477" data-entity-type="MINI_COMPANY" href="https://www.linkedin.com/company/techblick/" target="_blank">TechBlick</a> July 2021, shows, the KFS technology is evolving. At first in 2014, the average particle size was a 25-30um. It is now down to 3-9um and evolving towards sub-micron and even nano-sized particles, enabling direct integration with microLEDs of today and tomorrow! This is an important technology trend because it brings the QD vs phosphor competition even to the microLED space (previously QDs were the only game in town due to their small size) Furthermore, GE&#39;s KSF can now be formulated into air-stable inks based on encapsulant-free phosphors suitable for inkjet printing without nozzle clogging. It means that it can be even printed as a color converter atop microLED, in particular allowing one to use efficient blue microLEDs to create red color and/or only transfer a blue microLED color.&nbsp; <a data-attribute-index="6" data-entity-hovercard-id="urn:li:fs_miniProfile:ACoAAAIvgBYBfQjVeeqd_uc7uiIftwRomB9sV5I" data-entity-type="MINI_PROFILE" href="https://www.linkedin.com/in/ACoAAAIvgBYBfQjVeeqd_uc7uiIftwRomB9sV5I" target="_blank">James E. Murphy</a> offers also an interesting comparison of Cd-free InP QDs vs KSF for microLEDs. It argues that at very thin films (&lt;10um), QDs are more efficient. However, as the layer is thickened, perhaps to prevent blue color leakage, self-abosrption effects can kick-in, reducing the EQE. Thus, it is argued that KSF clearly wins at &gt;20um thickness given that it has no self absorption&nbsp; Finally, here is lack of ultra narrowband green phosphors leaving the space open to QDs. In particular, green perovskite QDs are very strong in this field. However, GE is advancing the development of its narrow-band GREEN phosphors. As shown below, these materials enable 100% DCI-P3. The performance is comparable to Beta Sialon but without cross talk with a KSF red emittesr. Furthermore, it offers 100% HTHH stability, enabling direct on-chip integration. Finally, it apepars to have QE levels approach &gt;90%. Of course, just like KFS, it has a slow PL decay time on the order of 90-450um (QD is ns) To learn more about QDs and microLEDs join TechBlick&#39;s event on 30NOV-1Dec: www.TechBlick.com/microLEDs <a data-attribute-index="8" href="https://www.linkedin.com/feed/hashtag/?keywords=microled&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6963447055776161792" target="_blank">#microled</a> <a data-attribute-index="9" href="https://www.linkedin.com/feed/hashtag/?keywords=quantumdots&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6963447055776161792" target="_blank">#quantumdots</a> <a data-attribute-index="10" href="https://www.linkedin.com/feed/hashtag/?keywords=phosphors&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6963447055776161792" target="_blank">#phosphors</a> <a data-attribute-index="11" href="https://www.linkedin.com/feed/hashtag/?keywords=displays&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6963447055776161792" target="_blank">#displays</a> <a data-attribute-index="12" href="https://www.linkedin.com/feed/hashtag/?keywords=inkjet&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6963447055776161792" target="_blank">#inkjet</a> <a data-attribute-index="13" href="https://www.linkedin.com/feed/hashtag/?keywords=miniled&highlightedUpdateUrns=urn%3Ali%3Aactivity%3A6963447055776161792" target="_blank">#miniled</a> <a data-attribute-index="14" data-entity-hovercard-id="urn:li:fs_miniProfile:ACoAAAB8WiEBRtw30q9Nx3b5lIFSkuhOjD753mk" data-entity-type="MINI_PROFILE" href="https://www.linkedin.com/in/ACoAAAB8WiEBRtw30q9Nx3b5lIFSkuhOjD753mk" target="_blank">Rachel A. Cassidy, PhD, MBA, CLP</a> <img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1660648163303-Evolution+of+KSF+Phosphors.png" style="width: 700px;" class="fr-fic fr-dib">&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1660648212373-KSF+vs+InP+QDs.png" style="width: 686px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1660648239294-KSF+Inkjet.png" style="width: 683px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1660648255502-GE+NArrow+band+green+phosphors.png" style="width: 667px;" class="fr-fic fr-dib"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1660648274762-TechBlick+MicroLEDs.png" style="width: 699px;" class="fr-fic fr-dib">

Phosphors or QDs for color conversion in LCD and microLED ? Which will win? This is an evolving technology space to watch.  Here,  it is shown that phosphor technology is evolving, enabling not just red but also green narrowband color conversation with small particle sizes compatible with microLEDs

Phosphors or QDs for color conversion in LCD and microLED ?

In a new review of the efficiency, usability, safety and security of automotive holographic HUDs, lead author <a href="http://www.eng.cam.ac.uk/profiles/js2459" target="_blank">Jana Skirnewskaja</a> and her PhD supervisor <a href="http://www.eng.cam.ac.uk/profiles/tdw13" target="_blank">Professor Tim Wilkinson</a>, say that while the technology can aid in providing safer and inclusive transportation, the impact on driver comfort and on overall road safety and security is not yet fully understood and must be addressed to ensure the development of modern vehicles that can be safely operated. The <a href="https://doi.org/10.1002/adma.202110463" target="_blank">findings</a> are reported in the journal Advanced Materials.HUDs work by projecting a transparent 2D or 3D digital image of navigational and hazard warning information, for example, onto the windscreen of the vehicle. These projected images then merge with the driver&rsquo;s view of the road ahead. Windshield HUDs, for example, are set up so that the driver does not need to shift their gaze away from the road in order to view the relevant, timely information. This technology helps to keep the driver&rsquo;s attention on the road, as opposed to the driver having to look down at the dashboard or navigation system.Technological advances in this area have led to HUDs with holographic displays and AR in 3D. This added depth perception makes it possible to project computer-generated virtual objects in real time into the driver&rsquo;s field of view to warn, inform or entertain the user. The driver&rsquo;s alertness to road obstacles is increased by enabling shorter obstacle visualisation times, and eye strain and driving stress levels are reduced.&nbsp;&ldquo;Holographic HUDs are paramount if we are to explore the possibilities of augmented and mixed reality for road safety,&rdquo; said Jana, who conducts her PhD research at the <a href="https://www.ceps-cdt.org/" target="_blank">EPSRC Centre for Doctoral Training (CDT) in Connected Electronic and Photonic Systems</a>, a joint centre with the University of Cambridge and UCL. &ldquo;Holographic HUDs can project 3D objects directly into the retina to achieve an AR experience. The technology is seen as the next new addition to tomorrow&rsquo;s connected vehicles, but managing an abundance of information while driving in this modern set-up requires the driver to multitask, leading to cognitive overload &ndash; this increases the likelihood of a collision while driving.&rdquo;According to their review, there are important challenges to be tackled with regards to the implementation of AR HUDs,&nbsp;with the following&nbsp;deemed to be&nbsp;the &ldquo;most important&rdquo;: creating a multifocal display, large viewing area without comprising the field of view; ensuring the optimal positioning on the windscreen; creating minimal invasiveness while driving by ensuring the accurate identification of hazards on the road.&ldquo;Further studies on driver distraction are required,&rdquo; said Jana. &ldquo;This could include analysis of the placement of content on the windshield and the placement of AR projections in the driver&rsquo;s field of view via behavioural, neurodiversity and system engineering studies.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1655471848354-ToC+image_CENTRE.jpg" style="width: 766px;" class="fr-fic fr-dib">The Cambridge researchers&#39; vision of the LiDAR derived AR HUD applied in a car setting. Credit: Department of Engineering, University of Cambridge. &nbsp;Developments in this field have led to&nbsp;<a href="http://www.eng.cam.ac.uk/news/3d-holographic-head-display-could-improve-road-safety" target="_blank">LiDAR (light detection and ranging)</a> data being trialled to create ultra-high-definition holographic representations of road objects that are beamed directly to the driver&rsquo;s eyes. LiDAR is commonly used in agriculture, archaeology and geography, but it is also being trialled in autonomous vehicles for obstacle detection. It is a remote sensing method that works by sending out a laser pulse to measure the distance between the scanner and an object. Meanwhile, the integration of machine learning algorithms (for gesture recognition and automatic obstacle detection) into HUDs, as well as metamaterials &ndash; an emerging class of artificially engineered ultralight materials with extreme functional properties &ndash; could, say the researchers, lead to customisable, transformative image projection capabilities designed to enhance road safety.&nbsp;&ldquo;Holographic AR HUDs have the potential to increase safety and security in transportation,&rdquo; said Jana. &ldquo;In the future, this technology can increase the interconnectedness of vehicles and with the interactive urban environment to reduce traffic accidents.&rdquo;In their review, the researchers say there is a need to develop an &ldquo;inclusive strategy&rdquo; for the driver where, for example, certain objects could be prioritised and placed into an area of personal preference by the driver based on their needs. Additionally, they say, focus is also needed on developing the technology for those who are visually and/or movement impaired, for example the elderly and those affected by disability. This is where machine learning could play a central role in &lsquo;intelligent&rsquo; collision avoidance, visual enhancements, and support for people with neurodiverse conditions, such as attention deficit hyperactivity disorder (ADHD), autism and dyslexia.While the researchers point out that holographic HUDs can improve road safety, they also advise that future legislative requirements are developed for safe automotive holographic video displays (that perceive road obstacles in full depth and within a 360&deg; field of view) and AR HUDs.&nbsp;&ldquo;This is a crucial step toward a full obstacle assessment for safety reasons and to prevent the driver from suffering from fatigue due to changing views resulting from holographic video displays and AR HUDs,&rdquo; added Jana.Another important point for consideration, they say, is ensuring secure information management by, for example, combining 3D hologram projection techniques with real-time encryption-decryption to generate colour holographic videos. Vehicle and driver data can then be shared with the smart urban environment.Reference: Jana Skirnewskaja; Timothy D. Wilkinson. &lsquo;<a href="https://doi.org/10.1002/adma.202110463" target="_blank">Automotive Holographic Head-Up Displays</a>.&rsquo; Advanced Materials (2022). DOI: 10.1002/adma.202110463

Road obstacle detection with machine learning algorithms (left) and 3D AR HUD navigating through public roads (right). Credit: Department of Engineering, University of Cambridge

Augmented reality (AR) head-up displays (HUDs) are widely considered to be the future of connected vehicles, but more human-centred studies are needed to assess the impact of AR on the driver while operating a vehicle on public roads, say Cambridge researchers.

Augmented reality head-up displays - navigating the next-gen driving experience

In this episode, we talk about how performance limitations of current microchips are being addressed by utilizing novel materials like graphene and bioinspired designs to address the needs of next generation computing and electronics. As always, you can find these and other interesting &amp; impactful engineering articles on Wevolver.com.&nbsp;<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/4c563405-4ade-4b6a-9070-a75a7d327eef?dark=false" class="fr-draggable" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true"></iframe><hr>This podcast is sponsored by <a href="https://www2.mouser.com/" id="isPasted" rel="nofollow" target="_blank">Mouser Electronics</a>. &nbsp; &nbsp;&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1654001595280-Mouser-sponsor-1-a.jpg" style="width: 766px;" class="fr-fic fr-dib"><hr>(3:46) -&nbsp;<a href="https://www.wevolver.com/article/graphene-hbn-breakthrough-to-spur-new-leds-quantum-computing" target="_blank">Graphene-hBN Computing</a>(16:44) -&nbsp;<a href="https://www.wevolver.com/article/spiderweb-microchip-sensors-allow-one-of-the-worlds-most-precise-microchip-sensor" target="_blank">Spiderweb Microchips</a>Episode 72 was brought to you by Mouser Electronics, Farbod &amp; Daniel&rsquo;s favorite electronics distributor. Click <a href="https://www.mouser.com/applications/wide-bandgap-beyond-silicon/" target="_blank">here</a> to read the article discussing &nbsp;how scientists are looking beyond silicon for the future of computer chips.<hr>About the podcast:Every day, some of the most innovative universities, companies, and individual technology developers share their knowledge on Wevolver. To ensure we can also provide this knowledge for the growing group of podcast listeners, we started a collaboration with two young engineers, Daniel Scott Mitchell &amp; Farbod Moghaddam who discuss the most interesting content in this podcast series.&nbsp;To learn more about this show, please visit the <a href="https://www.wevolver.com/profile/the.next.byte" target="_blank">shows page</a>. By following the page, you will get automatic updates by email when a new show is published.Be sure to give us a follow and review on <a href="https://podcasts.apple.com/nl/podcast/the-next-byte/id1548255861?l=en" rel="nofollow" target="_blank">Apple</a> podcasts, <a href="https://open.spotify.com/show/6lPPsRtegnivsRUEsQ09R7?si=IPMiah7xT_apJtPjqvXMlA" rel="nofollow" target="_blank">Spotify</a>, and most of your favorite podcast platforms!Take a few seconds to leave us a review. It really helps! <a href="https://apple.co/2RIsbZ2" rel="nofollow" target="_blank">https://apple.co/2RIsbZ2&nbsp;</a>if you do it and send us proof, we&rsquo;ll give you a shoutout on the show.

In this episode, we talk about how performance limitations of current microchips are being addressed by utilizing novel materials like graphene and bioinspired designs to address the needs of next generation computing and electronics.