Category Archives: Flexible Displays

Today, SEMI announced that SEMICON Japan, the exposition for the electronics manufacturing supply chain in Japan, will focus on smart applications as key drivers of the electronics industry. Over 30,000 attendees are expected to convene at SEMICON Japan at Tokyo Big Sight in Tokyo on December 13-15. Registration for the exhibition and programs is now open.

Both on the exhibition floors and in sessions, smart applications will be featured, including Smart Automotive, Smart Manufacturing, Smart MedTech and the Internet of Things (IoT), bringing the theme, “Dreams Start Here” to life.

Smart Automotive – On the show floor, Toyota and Tesla will share new Smart Automotive technologies. Two dedicated forums on Smart Automotive will be featured at SEMICON Japan:

  • IoT Key Technology Forum: Companies, including Nissan Motors, NVIDIA andHitachi Automotive Systems will share their perspectives on the future of Smart Automotive.
  • Smart Mobility Forum: The technologies shaping our future mobile society, including autonomous bus systems, robot cars and drones, are featured.

Smart Manufacturing – The Smart Manufacturing Forum will share the latest on advanced  manufacturing lines from two Japanese solution providers ─ Fuji Machine Manufacturing and Yokogawa Electric. On the exhibition floor, Peer Group, Siemens and Yokogawa Electric will showcase the technologies and products.

Smart MedTech – The Smart Healthcare Forum will feature the Internet Association Japan and Hitachi who will explore the development of medical electronics and the latest technologies and solutions brought by IoT and AI. On the show floor, companies providing key enabling technologies for wearable devices including JINS, Toyobo and YUASA Systems will exhibit in the Flexible Hybrid Electronics area.

WORLD OF IOT – Many of the above exhibits on smart applications and their enabling technologies will be located at the WORLD OF IOT, a technology showcase highlighting the companies, products, technologies, and applications enabling the IoT revolution. WORLD OF IOT will have more than 70 exhibitors including Fujitsu, Hitachi, IBM, Micron, Nokia, Panasonic, Soft Bank and Sony. SEMICON Japan also features two sessions on IoT technologies:

  • IoT Global Trends Forum: Executives from leading technology companies, including Arm, Intel and Sony, will discuss the technology development needed to reach a smarter and more connected world.
  • IoT Connectivity Forum: Presentations by wireless communication technology companies Ericsson and NTT Docomo on next-generation technology including 5G and LPWA, needed to accelerate the Industrial IoT and Smart Manufacturing.

 

All about Drones – SEMICON Japan will also present “All about Drones”─a spotlight on drones, a growing application of sensor and actuator technologies. A tear-down drone exhibit, drone lectures, and a demonstration area will allow visitors fly drones.

Osamu Nakamura, president of SEMI Japan said, “With all these exhibits and sessions, the semiconductor manufacturing supply chain will intersect with the growing application markets, technologies and players to find new opportunities for collaboration, innovation and growth. That’s why ‘Dreams Start Here’ at SEMICON Japan.”

For more information on the SEMICON Japan exposition and programs, visit http://www.semiconjapan.org/en.

The 63rd annual IEEE International Electron Devices Meeting (IEDM), to be held December 2-6, 2017 at the Hilton San Francisco Union Square hotel, may go down as one of the most memorable editions for the sheer variety and depth of its talks, sessions, courses and events.

Among the most-anticipated talks are presentations by Intel and Globalfoundries, which will each detail their forthcoming competing FinFET transistor technology platforms in a session on Wednesday morning. FinFET transistors are a major driver of the continuing progress of the electronics industry, and these platforms are as important for their commercial potential as they are for their technical innovations.*

Each year at the IEDM, the world’s best technologists in micro/nano/bioelectronics converge to participate in a technical program consisting of more than 220 presentations, along with other events.

“Those who attend IEDM 2017 will find much that is familiar, beginning with a technical program describing breakthroughs in areas ranging from mainstream CMOS technology to innovative nanoelectronics to medical devices. The Sunday Short Courses are also a perennial favorite because they are not only comprehensive but are also taught by accomplished world experts,” said Dr. Barbara De Salvo, Scientific Director at Leti. “But we have added some new features this year. One is a fourth Plenary session, on Wednesday morning, featuring Nobel winner Hiroshi Amano. Another is a revamped Tuesday evening panel. Not only will it focus on a topic of great interest to many people, it is designed to be more open and less formal.”

Other features of the IEDM 2017 include:

  • Focus Sessions on the following topics: 3D Integration and Packaging; Modeling Challenges for Neuromorphic Computing; Nanosensors for Disease Diagnostics; and Silicon Photonics: Current Status and Perspectives.
  • A vendor exhibition will be held, based on the success of last year’s event at the IEDM.
  • The IEEE Magnetics Society will again host a joint poster session on MRAM (magnetic RAM) in the exhibit area. New for this year, though, is that the Society will also hold its annual MRAM Global Innovation Forum on Thursday, Dec. 7 at the same hotel, enabling IEDM attendees to participate. (Refer to the IEEE Magnetics Society website.) The forum consists of invited talks by leading experts and a panel discussion.

Here are details of some of the events that will take place at this year’s IEDM:

90-Minute Tutorials – Saturday, Dec. 2
These tutorials on emerging technologies will be presented by leading technical experts in each area, with the goal of bridging the gap between textbook-level knowledge and cutting-edge current research.

  • The Evolution of Logic Transistors Toward Low Power and High Performance IoT Applications, Dr. Dae Won Ha, Samsung Electronics
  • Negative Capacitance Transistors, Prof. Sayeef Salahuddin, UC Berkeley
  • Fundamental, Thermal, and Energy Limits of PCM and ReRAM, Prof. Eric Pop, Stanford University
  • Hardware Opportunities in Cognitive Computing: Near- and Far-Term, Dr. Geoffrey Burr, Principal Research Staff Member, IBM Research-Almaden
  • 2.5D Interposers and High-Density Fanout Packaging as Enablers for Future Systems Integration, Dr. Venkatesh Sundaram, Associate Director, Georgia Tech 3D Systems Packaging Research Center
  • Silicon Photonics for Next-Generation Optical Interconnects, Dr. Joris Van Campenhout, Program Director Optical I/O, Imec

Short Courses – Sunday, Dec. 3
The day-long Short Courses provide the opportunity to learn about important developments in key areas, and they enable attendees to network with the industry’s leading technologists.

Boosting Performance, Ensuring Reliability, Managing Variability in Sub-5nm CMOS, organized by Sandy Liao of Intel, will feature the following sections:

  • Transistor Performance Elements for 5nm Node and Beyond, Gen Tsutsui, IBM
  • Multi-Vt Engineering and Gate Performance Control for Advanced FinFET Architecture, Steve CH Hung, Applied Materials
  • Sub-5nm Interconnect Trends and Opportunities, Zsolt Tokei, Imec
  • Transistor Reliability: Physics, Current Status, and Future Considerations, Stephen M. Ramey, Intel
  • Back End Reliability Scaling Challenges, Variation Management, and Performance Boosters for sub-5nm CMOS,Cathyrn Christiansen, Globalfoundries
  • Design-Technology Co-Optimization for Beyond 5nm Node, Andy Wei, TechInsights

Merged Memory-Logic Technologies and Their Applications, organized by Kevin Zhang of TSMC, will feature the following sections:

  • Embedded Non Volatile Memory for Automotive Applications, Alfonso Maurelli, STMicroelectronics
  • 3D ReRAM: Crosspoint Memory Technologies, Nirmal Ramaswamy, Micron
  • Ferroelectric Memory in CMOS Processes, Thomas Mikolajick, Namlab
  • Embedded Memories Technology Scaling & STT-MRAM for IoT & Automotive, Danny P. Shum, Globalfoundries
  • Embedded Memories for Energy-Efficient Computing, Jonathan Chang, TSMC
  • Abundant-Data Computing: The N3XT 1,000X, Subhasish Mitra, Stanford University

Plenary Presentations – Monday, Dec. 4

  • Driving the Future of High-Performance Computing, Lisa Su, President & CEO, AMD
  • Energy-Efficient Computing and Sensing: From Silicon to the Cloud, Adrian Ionescu, Professor, EPFL
  • System Scaling Innovation for Intelligent Ubiquitous Computing, Jack Sun, VP of R&D, TSMC

Plenary Presentation – Wednesday, Dec. 6

  • Development of a Sustainable Smart Society by Transformative Electronics, Hiroshi Amano, Professor, Nagoya University. Dr. Amano received the 2014 Nobel Prize in Physics along with Isamu Akasaki and Shuji Nakamura for the invention of efficient blue LEDs, which sparked a revolution in innovative, energy-saving lighting. His talk will be preceded by the Focus Session on silicon photonics.

Evening Panel Session – Tuesday evening, Dec. 5

  • Where will the Next Intel be Headquartered?  Moderator: Prof. Philip Wong, Stanford

Entrepreneurs Lunch
Jointly sponsored by IEDM and IEEE EDS Women in Engineering, this year’s Entrepreneurs Lunch will feature Courtney Gras, Executive Director for Launch League, a local nonprofit focused on developing a strong startup ecosystem in Ohio. The moderator will be Prof. Leda Lunardi from North Carolina State University. Gras is an engineer by training and an entrepreneur by nature. After leaving her job as a NASA power systems engineer to work for on own startup company, she discovered a passion for building startup communities and helping technology-focused companies meet their goals. Named to the Forbes ’30 Under 30′ list in 2016, among many other recognitions and awards, Gras enjoys sharing her stories of founding a cleantech company with young entrepreneurs. She speaks on entrepreneurship, women in technology and clean energy at venues such as TEDx Budapest, the Pioneers Festival, and the IEEE WIE International Women’s Leadership Conference.

 

In a flexible display, the backplane, frontplane, and any encapsulants are all made from flexible materials. To date, such displays have been used primarily because they are thinner, lighter, and more durable than comparable rigid displays, and to a lesser extent because they are conformable to rigid but non-flat surfaces in devices such as mobile phone handsets, automobile dashboards, and appliance control panels.

In 2017, key flexible display components achieved cost and performance parity with their rigid counterparts for the first time, thus removing a key market barrier and opening the door to rapid adoption in a variety of otherwise-rigid devices such as e-readers and wearables. Such displays may also be incorporated into truly flexible devices such as credit cards, shelving labels, and smart signage, and in the near future they may form the basis of rollable and foldable devices that define entirely new market categories.

According to a new report from Tractica, the four leading technologies in flexible displays are LED, LCD, OLED, and e-paper, and the main applications for these technologies are phones and tablets, wearables, shelving labels, signage, automotive dashboards, appliance control panels, TV and video displays, smart cards, e-writers, and e-readers. The market intelligence firm forecasts that flexible display shipments will increase from 169.9 million units in 2017 to 642.6 million units annually by 2022.

“The effect of flexible and conformable displays will be transformational,” says senior analyst Wil McCarthy. “They will literally change the appearance and function of our personal devices, our vehicles, our homes, and the built environment.”

Tractica’s report, “Flexible Displays”, examines the market trends and technology issues surrounding flexible displays and presents 6-year market forecasts, segmented by world region, for flexible display unit shipments, square meters, device pricing and revenue, and software applications during the period from 2017 through 2022. Flexible display applications are analyzed in depth, and the report also includes detailed profiles of 13 key industry players. An Executive Summary of the report is available for free download on the firm’s website.

A team of University of Wisconsin–Madison engineers has created the most functional flexible transistor in the world — and with it, a fast, simple and inexpensive fabrication process that’s easily scalable to the commercial level.

It’s an advance that could open the door to an increasingly interconnected world, enabling manufacturers to add “smart,” wireless capabilities to any number of large or small products or objects — like wearable sensors and computers for people and animals — that curve, bend, stretch and move.

Literal flexibility may bring the power of a new transistor developed at UW–Madison to digital devices that bend and move. PHOTO COURTESY OF JUNG-HUN SEO, UNIVERSITY AT BUFFALO, STATE UNIVERSITY OF NEW YORK

Literal flexibility may bring the power of a new transistor developed at UW–Madison to digital devices that bend and move. PHOTO COURTESY OF JUNG-HUN SEO, UNIVERSITY AT BUFFALO, STATE UNIVERSITY OF NEW YORK

Transistors are ubiquitous building blocks of modern electronics. The UW–Madison group’s advance is a twist on a two-decade-old industry standard: a BiCMOS (bipolar complementary metal oxide semiconductor) thin-film transistor, which combines two very different technologies — and speed, high current and low power dissipation in the form of heat and wasted energy — all on one surface.

As a result, these “mixed-signal” devices (with both analog and digital capabilities) deliver both brains and brawn and are the chip of choice for many of today’s portable electronic devices, including cellphones.

“The industry standard is very good,” says Zhenqiang (Jack) Ma, the Lynn H. Matthias Professor and Vilas Distinguished Achievement Professor in electrical and computer engineering at UW–Madison. “Now we can do the same things with our transistor — but it can bend.”

Ma is a world leader in high-frequency flexible electronics. He and his collaborators described their advance in the inaugural issue of the journal npj Flexible Electronics, published Sept. 27.

Making traditional BiCMOS flexible electronics is difficult, in part because the process takes several months and requires a multitude of delicate, high-temperature steps. Even a minor variation in temperature at any point could ruin all of the previous steps.

Ma and his collaborators fabricated their flexible electronics on a single-crystal silicon nanomembrane on a single bendable piece of plastic. The secret to their success is their unique process, which eliminates many steps and slashes both the time and cost of fabricating the transistors.

“In industry, they need to finish these in three months,” he says. “We finished it in a week.”

He says his group’s much simpler high-temperature process can scale to industry-level production right away.

“The key is that parameters are important,” he says. “One high-temperature step fixes everything — like glue. Now, we have more powerful mixed-signal tools. Basically, the idea is for flexible electronics to expand with this. The platform is getting bigger.”

His collaborators include Jung-Hun Seo of the University at Buffalo, State University of New York; Kan Zhang of UW–Madison; and Weidong Zhou of the University of Texas at Arlington.

SEMICON Europa 2017 will take place in Munich for the first time, co-located with productronica (14-17 November in Munich, Germany). SEMICON Europa will showcase the critical issues shaping the entire electronics manufacturing supply chain. Fourexecutive keynotes will share their thought leadership on current opportunities for Europe: Maria Marced, president, TSMC Europe; Stefan Finkbeiner, CEO, Bosch Sensortec; and Frank M. Rinderknecht, founder and CEO of Rinspeed Inc.

“Innovations in semiconductor manufacturing are at the heart of the value chain driving innovations enabling key future growth drivers in Mobile, Automotive, Medical, passive and intelligent computing as well as AR and VR,” stated Laith Altimime, president, SEMI Europe. SEMICON Europa programs, sessions, and speakers will illuminate this year’s theme “Empowering Innovation and Shaping the Value Chain.”  Highlights of SEMICON Europa include:

  • Fab Management Forum: Quality Challenges – Solutions for Tomorrow ─ Topics include:Future of digital vehicles and requirements for quality and availability of semiconductors with Daimler AG, an analysis of Human failure and mindset change by European School of Management and Technology (ESMT) Berlin, and how innovative sensor and analytics solutions enable new applications in the fab of tomorrow by KINEXON GmbH.
  • Advanced Packaging Conference: Electronics Packaging and Test for Future Mobility ─With Yole Développement on the dynamics of the advanced packaging ecosystem, Robert Bosch GmbH on automotive, Infineon Technologies on packaging for automotive ─ challenges and solutions, RoodMicrotec GmbH on wafer and final test in the new era of electronics, and STMicroelectronics on packaging challenges for robust miniaturization.
  •  Power Electronics Conference: From Materials to Systems,The Latest Innovations ─Covering power electronics applications for Automotive by Fraunhofer Institute for Integrated Systems and Device Technology IISB, a forecast of the next five years to reveal how technology development will shape the power electronics market by Yole Développement, and  Cambridge University on Silicon and Wide bandgap devices in power electronics.
  • New! Materials Conference: Connected World ─ New Material Challenges and Solutions ─Includes a keynote by Christophe Maleville, SOITEC, on how to better optimize performance, power budget and cost to meet applications requirements; plus presentations from Volkswagen AG on the need for new industry alliances in automotive, FUJIFILM on maximum utilization of chemically amplified resist, and Dow Chemical on the information age and connectivity enabled by advanced electronic materials. The free Webinar “Connected World: New Material Challenges and Solutions – Market Update and Outlook is planned on 27 September.
  • New! European Connect2Car Forum ─ A new Forum in collaboration with SAE International. Insights for automotive OEM and supplier executives, consumer electronics leaders, mobile application developers, and aftermarket entrepreneurs focusing on enhancing the driver experience and accelerating the deployment of connected and autonomous vehicle technologies.
  • New! 2017FLEX Europe “Be Flexible” ─ New collaboration between FLEX and Fraunhofer EMFT. Insights on innovative solutions for flexible and stretchable systems by Würth Elektronik GmbH,  technology and applications of chip-film patch for hybrid systems in foil by IMS CHIPS, new capabilities and applications of flexible components by E Ink Corporation, and insight on how potentials of System-in-Package technologies will affect the future by Bosch.

SEMI and Messe München Joint Press Conference will take place on 14 November at 11:00-12:00, at Messe München Press Conference Center.

The large thin film transistor (TFT) display market is expected to continue to expand in 2017 despite slower end-market demand, according to IHS Markit (Nasdaq: INFO).

While unit shipments are expected to be up 1 percent in 2017 to 688 million units, compared to the previous year, area shipment forecasts show growth of 6 percent in the same period, to 180 million square meters.

Figure 1

Among displays of 9 inches or larger, tablet PC displays are on track to record the highest year-on-year growth in unit shipments in 2017, with 10 percent growth to 93 million units. “It is because first-tier set brands are increasing the number of tablet PC models with larger screens. The new 10.5-inch iPad pro is a good example,” said Peter Su, principal analyst at IHS Markit.

The second fastest-growing application is notebook PC displays, with a 4 percent year-on-year growth to about 175 million units. “Chinese panel makers are aggressively trying to expand in this market, while first-tier panel makers are actually retreating panel production,” Su said.

On the flip side, TV displays are showing a contraction in 2017 by 3 percent year on year, dropping to 257 million units due to slower end-market demand. “Prices of large displays, particularly TV panels, have stayed high for almost a year. TV brands started revising down their business plan, cutting their panel purchases,” Su said.

In terms of area shipments, however, large displays for all applications are forecast to see growth in 2017 as larger screens become more popular with consumers. TV display accounts for 78 percent of total large display shipments by area, and is expected to see a 5 percent growth in 2017.

“First-tier panel makers, especially South Korean companies, already started shifting their production to larger sizes — 49 inches or larger — while reducing production of smaller panels, with lower profitability, to achieve better financial performance,” Su said. “Chinese panel makers are following suit and started increasing production of larger TV displays to 43-inch or larger.”

For a panel manufacturer’s perspective, preparing for potential oversupply in the near future is another reason behind the TV size migration. New fabs are under construction in China, including 10.5 generation, and could increase supply significantly.  “One way for panel makers to overcome the oversupply is to increase area consumption via size migration,” Su said.

LG Display is expected to continue accounting for the largest market share in 2017 with 21 percent as measured by unit shipments. BOE, a Chinese display maker that has been increasing its shipments significantly, is forecast to take 20.7 percent, up 2 percentage points from 2016, gaining on LG Display.

Figure 2

Flex Logix Technologies, Inc., the supplier of embedded FPGA IP and software, today announced that it has joined the TSMC IP Alliance Program included in TSMC’s Open Innovation Platform.

Flex Logix has worked closely with TSMC since Flex Logix was founded in 2014 and now has its EFLX Embedded FPGA IP and software tools available for TSMC 16FFC/FF+, TSMC 28HPM/HPC and TSMC 40ULP/LP. For each EFLX IP core in each process, Flex Logix has designed, fabricated and validated a validation chip to demonstrate full-speed, high utilization performance and power specs over the full temperature and voltage operating ranges. Flex Logix has worked with TSMC to ensure its documentation, design methodology, validation chip architecture and testing all meet TSMC’s rigorous standards to become an IP Alliance Member.

EFLX embedded FPGA arrays are available on these TSMC processes in a wide range of sizes from 100 LUTs to >100,000 LUTs with options for DSP/MAC and any type/size RAM. Flex Logix will implement EFLX embedded FPGA on any additional TSMC process node as TSMC customers request. Over time, Flex Logix expects EFLX to be available on every node from 180nm to 7nm.

“Flex Logix offers high density, high performance, scalable embedded FPGA,” said Suk Lee, TSMC Senior Director, Design Infrastructure Marketing Division. “We see good customer activity and interest in this emerging Semiconductor IP category and are pleased to have Flex Logix as an IP Alliance Member.”

Embedded FPGA is a new type of semiconductor IP enabling high-volume chip designers to incorporate reconfigurable logic to allow chips to be updated even in-system to adapt to new standards, new protocols, new algorithms and to customize chips for customers faster and more cost effectively than mask changes. Applications for embedded FPGA exist for networking, wireless base station, data center, deep learning, microcontroller, IoT, aerospace/defense and a range of other markets.

“We are proud to be joining the TSMC IP Alliance and appreciate TSMC’s support in helping us achieve membership,” said Geoff Tate, CEO of Flex Logix. “Our customers are in fab, in design, and in evaluation of EFLX embedded FPGA for a wide range of applications and our IP Alliance membership will enable us to support them even better going forward.”

FlexTech, a SEMI strategic association partner, will host a one-day Flexible Hybrid Electronics and Sensors Automotive Industry workshop in Detroit, Michigan on September 13, 2017 to explore how FHE adds functionality, decreases weight and impacts design. Automotive and electronics industry leaders will gather to discuss the market demands and challenges with automotive technology and present disruptive changes brought by flexible hybrid electronics (FHE) and sensors.

The forum will breakdown the topic into four key areas: OEM applications; market analysis and forecasts; challenges to integration; and solutions for Tier 2 and Tier 3 suppliers. Speakers include representatives from SBD Automotive, Fiat-Chrysler Group LLC, Velodyne LiDAR, Lumitex, Alpha Micron, NextFlex, Auburn University, Universal Instruments, Interlink Electronics, Georgia Institute of Technology, DuPont Photovoltaics & Advanced Materials and more.

“This forum is an excellent opportunity to discover the possibilities of flexible electronic systems incorporating advanced semiconductors, MEMS, and sensors, which will provide lightweight, sensor networks that conform, curve, and possibly more.  New automotive applications in this area will enable wholly new approaches for the in-cabin driving experience,” said Dr. Melissa Grupen-Shemansky, CTO for Flexible Electronics & Advanced Packaging at SEMI | FlexTech.

Company tours to Ford and a networking dinner are scheduled for September 12, 2017. For more information on the forum and how to register visit the event websiteat www.semi/org/en/FHE-forum-summary.

Rechargeable batteries are essential for powering our personal electronic devices. To meet the novel functions of next-generation electronics, including foldable displays, flexible power sources are needed. However, conventional batteries are rigid and unable to adapt to the demands of flexible devices. Low-cost, rechargeable batteries containing naturally abundant elements, such as zinc, are appealing, but flexible batteries based on zinc require a different preparation method from conventional batteries.

In their article in Advanced Energy Materials, Xu Chen, Bin Liu, Cheng Zhong, and co-workers have developed a high-performance, flexible air electrode for the Zn–air battery by devising a simple fabrication technique.

The technique involves electrodeposition with fast heat treatment to grow ultrathin mesoporous Co3O4 layers on the surface of carbon fibers on a carbon cloth. These ultrathin Co3O4 layers have a maximum contact area on the conductive support, facilitating rapid electron transport and preventing the aggregation of the layers.

Benefiting from the high utilization degree of active materials and rapid charge transport, the mass activity for oxygen reduction and evolution reactions of the ultrathin electrode is more than 10 times higher than that of the carbon cloth loaded with commercial Co3O4 nanoparticles. The as-assembled flexible Zn–air battery based on the ultrathin electrode exhibits excellent rechargeability (≈1.03 V discharge voltage and ≈1.95 V charge voltage at 2 mA cm–2), with a high charge density of 546 Wh kg–1. It also has a high cycling stability, where no obvious loss occurred after 10 hours of galvanostatic discharge–charge testing or after 300 mechanical bending cycles.

The authors also integrated a flexible display into the device. Despite repeated bending and twisting, the device maintains its mechanical integrity and discharge performance. When the device is cut by scissors, there is no perceptible change in the display brightness, signaling safe and reliable operation if the device is damaged.

To find out more about this flexible battery, please visit the Advanced Energy Materials homepage.

Imagine slipping into a jacket, shirt or skirt that powers your cell phone, fitness tracker and other personal electronic devices as you walk, wave and even when you are sitting.

A new, ultrathin energy harvesting system developed at Vanderbilt University’s Nanomaterials and Energy Devices Laboratory has the potential to do just that. Based on battery technology and made from layers of black phosphorus that are only a few atoms thick, the new device generates small amounts of electricity when it is bent or pressed even at the extremely low frequencies characteristic of human motion.

“In the future, I expect that we will all become charging depots for our personal devices by pulling energy directly from our motions and the environment,” said Assistant Professor of Mechanical Engineering Cary Pint, who directed the research.

The new energy harvesting system is described in a paper titled “Ultralow Frequency Electrochemical Mechanical Strain Energy Harvester using 2D Black Phosphorus Nanosheets” published Jun.21 online by the journal ACS Energy Letters.

“This is timely and exciting research given the growth of wearable devices such as exoskeletons and smart clothing, which could potentially benefit from Dr. Pint’s advances in materials and energy harvesting,” observed Karl Zelik, assistant professor of mechanical and biomedical engineering at Vanderbilt, an expert on the biomechanics of locomotion who did not participate in the device’s development.

Currently, there is a tremendous amount of research aimed at discovering effective ways to tap ambient energy sources. These include mechanical devices designed to extract energy from vibrations and deformations; thermal devices aimed at pulling energy from temperature variations; radiant energy devices that capture energy from light, radio waves and other forms of radiation; and, electrochemical devices that tap biochemical reactions.

“Compared to the other approaches designed to harvest energy from human motion, our method has two fundamental advantages,” said Pint. “The materials are atomically thin and small enough to be impregnated into textiles without affecting the fabric’s look or feel and it can extract energy from movements that are slower than 10 Hertz–10 cycles per second–over the whole low-frequency window of movements corresponding to human motion.”

Doctoral students Nitin Muralidharan and Mengya Li co-led the effort to make and test the devices. “When you look at Usain Bolt, you see the fastest man on Earth. When I look at him, I see a machine working at 5 Hertz,” said Muralidharan.

Extracting usable energy from such low frequency motion has proven to be extremely challenging. For example, a number of research groups are developing energy harvesters based on piezoelectric materials that convert mechanical strain into electricity. However, these materials often work best at frequencies of more than 100 Hertz. This means that they don’t work for more than a tiny fraction of any human movement so they achieve limited efficiencies of less than 5-10 percent even under optimal conditions.

“Our harvester is calculated to operate at over 25 percent efficiency in an ideal device configuration, and most importantly harvest energy through the whole duration of even slow human motions, such as sitting or standing,” Pint said.

The Vanderbilt lab’s ultrathin energy harvester is based on the group’s research on advanced battery systems. Over the past 3 years, the team has explored the fundamental response of battery materials to bending and stretching. They were the first to demonstrate experimentally that the operating voltage changes when battery materials are placed under stress. Under tension, the voltage rises and under compression, it drops.

The team collaborated with Greg Walker, associate professor of mechanical engineering, who used computer models to validate these observations for lithium battery materials. Results of the study were published Jun. 27 in the journal ACS Nano in an article titled “The MechanoChemistry of Lithium Battery Electrodes.”

These observations led Pint’s team to reconstruct the battery with both positive and negative electrodes made from the same material. Although this prevents the device from storing energy, it allows it to fully exploit the voltage changes caused by bending and twisting and so produce significant amounts of electrical current in response to human motions.

The lab’s initial studies were published in 2016. They were further inspired by a parallel breakthrough by a group at Massachusetts Institute of Technology who produced a postage-stamp-sized device out of silicon and lithium that harvested energy via the effect Pint and his team were investigating.

In response, the Vanderbilt researchers decided to go as thin as possible by using black phosphorus nanosheets: A material has become the latest darling of the 2D materials research community because of its attractive electrical, optical and electrochemical properties.

Because the basic building blocks of the harvester are about 1/5000th the thickness of a human hair, the engineers can make their devices as thin or as thick as needed for specific applications. They have found that bending their prototype devices produces as much as 40 microwatts per square foot and can sustain current generation over the full duration of movements as slow as 0.01 Hertz, one cycle every 100 seconds.

The researchers acknowledge that one of the challenges they face is the relatively low voltage that their device produces. It’s in the millivolt range. However, they are applying their fundamental insights of the process to step up the voltage. They are also exploring the design of electrical components, like LCD displays, that operate at lower than normal voltages.

“One of the peer reviewers for our paper raised the question of safety,” Pint said. “That isn’t a problem here. Batteries usually catch on fire when the positive and negative electrodes are shorted, which ignites the electrolyte. Because our harvester has two identical electrodes, shorting it will do nothing more than inhibit the device from harvesting energy. It is true that our prototype will catch on fire if you put it under a blowtorch but we can eliminate even this concern by using a solid-state electrolyte.”

One of the more futuristic applications of this technology might be electrified clothing. It could power clothes impregnated with liquid crystal displays that allow wearers to change colors and patterns with a swipe on their smartphone. “We are already measuring performance within the ballpark for the power requirement for a medium-sized low-power LCD display when scaling the performance to thickness and areas of the clothes we wear.” Pint said.

Pint also believes there are potential applications for their device beyond power systems. “When incorporated into clothing, our device can translate human motion into an electrical signal with high sensitivity that could provide a historical record of our movements. Or clothes that track our motions in three dimensions could be integrated with virtual reality technology. There are many directions that this could go.”