MD+DI Online is part of the Informa Markets Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

How Shared Mobility Will Change EV and Battery Design

Automotive engineers and battery makers will need to consider how use-cases will drive the design of their products in the age of shared mobility, an expert will tell attendees at the upcoming Battery Show.

“People are going to do what’s easiest and most convenient for them,” Don Tappan, vice president of the venture capital firm, Braemer Energy Ventures, told Design News. “For a long time, that meant having their own car and driving it. But what’s easiest and most convenient now is to have options. And carmakers need to be thoughtful about that.”

Don Tappan of Braemer Energy Ventures: “If you want to have a big battery that can solve 99.9% of your use cases, it can get very expensive and your battery capacity can be under-utilized.” (Image source: Braemer Energy Ventures)

The dawn of ridesharing companies, such as Lyft, Uber, Maven, and others, will change the way consumers in the future think about their vehicles, Tappan said. And if manufacturers are prepared for that change, it could affect the size, capacity, and chemistry of future electric vehicle batteries as well as hybridization, intelligence, and even the crashworthiness of those vehicles.

In the future, there will be a wide spectrum of use-cases, ranging from those who drive 50 miles into the city to work every day using their own car to those who live in the city and walk to their offices, using ridesharing services to fill the occasional need for a car. And within that spectrum lies a range of powertrain and ownership models that will serve the needs of consumers, Tappan said. As a result, automakers will need to be aware that some use-cases may require EVs with big batteries, while others call for medium-size batteries and still others need small batteries combined with internal combustion engines.

Shared mobility will play a big role in the future because it will serve to fill in the gaps between different types of vehicles. For example, owners who have a short daily commute and a charge station at the office may need an EV with only a small- or medium-sized battery. If they take longer trips on weekends, they could use ridesharing or rental cars, he added. “So instead of the electric vehicle having to be everything to everyone, it can be one thing to one person on one day, and one thing to another person on another day,” Tappan said.

Battery capacity could also be closely linked with charging infrastructure. For example, Uber drivers who use their cars 14 hours a day could need bigger batteries if charging opportunities are unavailable or smaller batteries if fast-charge stations are abundant in their area, Tappan said.

Consumers, too, will need to think about their most cost-effective options. “The point is, big batteries are expensive,” Tappan told us. "If you want to have a big battery that will solve 99.9% of your use-cases, it can get very expensive and your battery capacity can be under-utilized. Whereas, if you only need to solve 75% of your use cases, you may be able to get by with a smaller, less-expensive battery.”

Shared mobility may be a key to that 75% scenario, Tappan said. “If the sharing is done properly and with the right infrastructure, then sharing may be easier than owning,” he added.

As ridesharing grows, it will profoundly affect the design choices that are now facing engineers. And those choices will become clearer with time—especially as shared mobility data becomes more available. “When you have millions of vehicles, it changes the world,” Tappan said. “So you need to take that real-world feedback and apply it to next-generation vehicles. That way, you can keep the designs moving in parallel with consumer demands.”

Don Tappan will discuss shared mobility and how it affects design in a session called EVs and Hybrids in a New Mobility Future on September 11 in Novi, MI.  

Senior technical editor Chuck Murray has been writing about technology for 34 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and auto.

 

The Battery Show logoNorth America's Premier Battery Conference.
Join our in-depth conference program with over 100 technical discussions covering topics from new battery technologies and chemistries to BMS and thermal management. 
The Battery Show. Sept. 11-13, 2018, in Novi, MI. Register for the event, hosted by Design News’ parent company UBM.

Novel, Light-Based Data Storage Eyed for Future Data Warehousing

Researchers in Australia are paving the way to considerably extending the amount of data storage that future devices can hold. This development stems from a novel and energy-efficient approach to storing data using light.

Specifically, researchers from the University of South Australia and University of Adelaide—collaborating with researchers at the University of New South Wales—have developed tiny, nano-sized crystals of salt encoded with data using light from a laser. Scientists are eying the new storage technique for next-generation storage for unprecedented amounts of data, such as those currently stored in data warehouses, said Nick Riesen, a research fellow at the University of South Australia.

Exceeding Limits

“We have been looking at a novel optical-data-storage technique with the potential to greatly extend beyond the limits of traditional data storage,” he told Design News. “The technology allows for multiple bits to be stored at a single point, and the technique has the potential to be extended to 3D platforms for potentially tera- to petabyte storage.”

With the explosion of technologies like social media and cloud computing, much more data exists in digital form than even five years ago. While data these days can be stored in the cloud, data-storage devices like hard-drive disks and solid-state storage, which are current options for hardware-based storage, are reaching their limits, Riesen said.

Enter the new method developed by Riesen and University of Adelaide PhD student Xuanzhao Pan. It is based on nanocrystals with light-emitting properties, which can be efficiently switched on and off in patterns that represent digital information. Researchers used lasers to alter the electronic states, and therefore the fluorescence properties, of the crystals, they said.

laser data
University of Adelaide PhD student Xuanzhao Pan (left) and University of South Australia research fellow Nic Riesen have developed a data-storage technology that could replace current magnetic-disk and solid-state technologies to provide unprecedented levels of storage capacity. (Image source: University of South Australia)

The team’s work demonstrates rewritable data storage in crystals that are hundreds of times smaller than that visible with the human eye. Researchers showed that these fluorescent nanocrystals could represent a promising alternative to traditional magnetic and solid-state data storage, as well as Blu-ray discs, Riesen said.

“The demonstration has shown optical data-storage approaching the single nanocrystal level,” he explained. “It’s unique in that it allows for energy-efficient, multilevel optical-data encoding that is rewritable and also at the nanoscale. This demonstration serves as a building block for 3D memory platforms with the potential for very high storage capacities.”

Key to the material used in the crystals is samarium, the ion of which can be switched with UV light, he explained. “It is this switching that is the basis of the data storage, as it alters the fluorescence properties of the material,” he said. “The host material BaFCl (an alkaline-earth fluorohalide) is critical in ensuring the switching is efficient.” The team published a paper on its work in the journal Optics Express.

Riesen said that the main commercial market for the technology would be archival data storage for big data sets either in the form of 2D or 3D memory. “The technology would be ideal for long-term archival data storage in warehouses, due to the low potential cost of such a medium compared to, for instance, solid state drive technologies,” he said. There also is potential for use in the broader consumer market, Riesen added.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.

 

Pacific Design and ManufacturingSAVE THE DATE FOR PACIFIC DESIGN & MANUFACTURING 2019! 
Pacific Design & Manufacturing, North America’s premier conference that connects you with thousands of professionals across the advanced design & manufacturing spectrum, will be back at the Anaheim Convention Center February 5-7, 2019! Don’t miss your chance to connect and share your expertise with industry peers during this can't-miss event. Click here to pre-register for the event today!

 

Specialty plastics extruder Pexco acquires Custom Extrusion Inc.

Specialty plastics extruder Pexco acquires Custom Extrusion Inc.

Pexco plastic extrusionSpecialty plastics extruder Pexco LLC (Alpharetta, GA) announced on Aug. 14 the acquisition of Custom Extrusion Inc. (CEI), a profile extruder with facilities in Sheffield, MA, and Asheboro, NC.

CEI was founded in Massachusetts in 1957 and experienced some of its earliest success in the engineering and development of lighting profiles, according to a press release distributed by Pexco. In 1993, the company expanded to North Carolina to meet the growing needs of its customer base. Since that time, the company has expanded into a variety of specialty industrial market segments.

“We are delighted to welcome Custom Extrusion Inc. to the Pexco family,” said Pexco CEO Sam Patel, adding that “CEI brings a wealth of expertise in lighting and custom industrial extrusions.”

Since 2009, Pexco has made multiple acquisitions, growing into the largest custom industrial extrusion company in North America.

Pexco was acquired earlier this year by private equity group AEA Investors, and CEI is its first acquisition under the new ownership. “We look forward to the continued pursuit of acquisitions that fit our core objectives, enabling us to enhance our suite of capabilities and expand our geographic footprint as the largest custom extruder in North America,” said Patel.

Pexco operates multiple plants across the United States and Mexico, providing standard and specialty parts and components to manufacturers and end-users for custom applications in the specialty industrial, lighting, traffic safety, fence and filtration industries. All of its plants are certified to ISO 9001:2015 and ISO 14001.

Automotive suppliers spooked by Trump trade policies, according to business barometer

Automotive suppliers spooked by Trump trade policies, according to business barometer

uncertaintyDespite a strong sales and production environment, a pessimistic outlook prevails across the automotive supply base because of trade policy uncertainty, according to a quarterly report from the Original Equipment Suppliers Association (OESA) based in Southfield, MI. The quarterly OESA barometer surveys executives among North American automotive suppliers to gauge their 12-month outlook. The Q3 barometer posts a negative reading of 43 for the quarter, seven points below the neutral level of 50.

Even with strong economic fundamentals—low unemployment, high consumer confidence and robust vehicle sales—the Q3 2018 Supplier Barometer Index (SBI) reflects negative repercussions from the Trump administration’s current trade-policy agenda. The latest OESA SBI reading dropped 10 points from the Q2 2018 report, and is in sharp contrast to the positive levels of 57 and 53 in the first and second quarters of 2018, respectively.

Concerns also remain over supply-chain risks, commodity prices, the impact of Section 232 and Section 301 tariffs, as well as the fate of stalled NAFTA negotiations in the context of midterm congressional elections. Each concern adds uncertainty to the planning environment, causing automakers and suppliers to reassess, revise and potentially postpone incremental investments until there is greater clarity.

“Policy uncertainty serves to constrain additional capacity investment and accelerate volatility through the supply chain, adding risk down the tiers,” said Mike Jackson, OESA’s Executive Director of Strategy and Research and author of the study. “Now, more than ever, suppliers should strive to use the increasing market turbulence to their advantage by assessing and prioritizing alternative scenarios beyond the near-term to realize their strategy for success.”

Supplier executive responses reflected a “universal increase in pessimism over prior quarter survey results,” said the OESA summary. Some 38% of responses from smaller, more regionally focused suppliers, reflected increasing pessimism, twice the rate compared with the prior quarter. Even more dramatic, 75% of executive responses from larger suppliers, with revenue between $500 million and $1 billion, showed a sharp increase in pessimism, up from 38% in Q2 2018.

Looking at globalization, the barometer underscores that supplier export activities provide a meaningful contribution to overall market strength. Survey responses highlight a median of 10% of U.S. supplier production exported in 2018. Median allocation of U.S. exports by country rank Mexico the top destination (50%), followed by Canada (30%), while Europe and Asia each reflect a 20% share.

Supply-chain survey results show that 47% of respondents anticipate North American supplier capacity to face rationalization pressures over the next year. Policy uncertainty serves to constrain additional capacity investment and accelerate volatility through the supply chain. A concerning trend is emerging as the number of financial watch-list suppliers has increased considerably, said the OESA report.

Further supply concerns include persistent timing pressures due to late design changes or delayed part validation. Expect these factors to be compounded as steel shortages caused by tariffs drive more supplier changes and require additional late engineering and validation work.

Nevertheless, the automotive industry remains robust and is poised to achieve a new milestone. For the first time ever, North American vehicle production is forecast to surpass 17 million units for the fifth consecutive year, with 17.3 million units projected to be produced in 2018.

7 of Bleeding Edge's Most Powerful Moments

The Bleeding Edge is a Netflix documentary that doesn’t pull any punches when it comes to talking about how patients are affected by medical devices that aren’t working properly. The documentary asserts that one of the key reasons these implants aren't working is because the 510(k) process isn’t as stringent as it needs to be and device firms aren't testing their technologies adequately. Throughout the 98-minute documentary, viewers are introduced to patients trying to make sense of their lives after being hurt or irrevocably changed by being implanted with a faulty medical device.  Here are several key moments coming from the documentary.

It’s showtime for medical injection molding at MD&M/PLASTEC Minneapolis

It’s showtime for medical injection molding at MD&M/PLASTEC Minneapolis

The Twin Cities region in the great state of Minnesota is one of the premier medical technology hubs in the United States. It’s where the first battery-powered pacemaker was invented in the late-1950s by Earl Bakken, who was running a little medical equipment repair shop at the time. The business was named Medtronic. Today, of course, Medtronic is one of the largest medical device companies in the world, and its shadow looms large over the region, where it has its operational headquarters. Numerous other medical technology companies and a long-tail supply chain have kept the region consistently ensconced in the upper reaches of surveys ranking the top medtech hubs. It’s no coincidence, then, that UBM, which also produces PlasticsToday, has successfully organized the Medical Design & Manufacturing (MD&M) trade show and conference in Minneapolis for more than two decades.

The event has grown over the years: PLASTEC Minneapolis co-located with MD&M in 2016, and the event now features five other co-located shows devoted to packaging, automation, design and manufacturing and embedded systems. Today, it is billed as the Midwest’s largest annual advanced design and manufacturing event.

Leading up to the show, which runs Oct. 31 and Nov. 1, 2018, at the Minneapolis Convention Center, PlasticsToday will publish previews of conference topics, including speaker interviews, and unique features on the show floor that await attendees. In this article, we highlight two injection molding machine makers, Sumitomo (SHI) Demag Plastics Machinery (Norcross, GA) and Arburg Inc. (Rocky Hill, CT), both of which will be running equipment on the show floor.

Given the medtech legacy of the region and the flagship MD&M event, Arburg and Sumitomo (SHI) Demag will emphasize medical molding applications.

Arburg injection molding machine
Arburg will demo a 375 V vertical clamp and injection unit machine, similar to the one pictured here, at the
co-located PLASTEC and MD&M Minneapolis event.

“We have a large customer base in the Twin Cities area, which has a large medical molding community,” Michael Stark, National Sales Manager for Arburg, told PlasticsToday. His company’s molding systems are ideal for medical applications, said Stark, because of their “speed, accuracy, cleanliness and flexibility.” He added that Arburg supports an “almost unlimited number of configurations between platen size and injection unit size, which is often critical for medical.” The company can also provide several medical-related options such as “HEPA filtration, special finishes and special options for cleaning,” said Stark.

Sumitomo (SHI) Demag has been coming to the Minneapolis show for a couple of years, said Tony Marchelletta, Regional Manager. “We have had consistent growth in this region, and we attribute much of that success to MD&M and PLASTEC Minneapolis as well as the big players who are based here—3M, Medtronic, Abbott and so forth—who send a number of engineers to the show,” Marchelletta told PlasticsToday.

Medical technology is one of the three key markets targeted by Sumitomo (SHI) Demag, according to Marchelletta, with an emphasis on implantable devices and drug dispensing systems. High-speed machines with high-cavitation molds tend to do very well in these applications, he added.

Machines on the show floor

On the MD&M/PLASTEC Minneapolis show floor, Arburg will be running a 375 V vertical clamp and injection unit machine. “We will treat the surface of a stainless-steel radius gauge insert using plasma technology and insert the part into the mold,” explained Stark. A different set of molding parameters in two cavities will alternate every other cycle, and the automation system fits within the footprint of the standard machine, he added.

For its part, Sumitomo (SHI) Demag is bringing its SE50EV-A machine to the event. It will be equipped with a “proprietary and fairly unique barrel and screw assembly for micro-molding temperature- and shear-sensitive materials for bioresorbable products and other items of that nature," said Marchelletta. The company has not nailed down the mold that it will be bringing, but it will probably be producing a small medical part with an intricate design that highlights the capabilities of the machine, he added.

Sumitomo (SHI) Demag SE50EV-A injection molding machine
Sumitomo (SHI) Demag's SE50EV-A injection molding machine features a proprietary barrel and screw assembly suited for micro-molding temperature- and shear-sensitive materials.

“The all-electric machine is suited for cleanroom use, and its consistency is second to none, especially with our barrel-screw technology,” said Marchelletta. “Bioresorbable and custom materials tend to be very costly, so you want to get a robust quality process dialed in. You don’t want to waste time or material.”

Arburg (booth 923) and Sumitomo (SHI) Demag (booth 823) will be among 500+ exhibitors showcasing advances in injection molding, rapid prototyping, automation, materials and additives and much more at the co-located MD&M and PLASTEC Minneapolis event. A full slate of conference sessions will explore topics related to R&D and product development, smart manufacturing, collaborative robotics and 3D printing. The trade show and conference comes to the Minneapolis Convention Center on Oct. 31 and Nov. 1, 2018. For full information about the event, go to the PLASTEC Minneapolis website.

Building a Better Insulin Infusion System

Pixabay Building a Better Insulin Infusion System

Capillary Biomedical is looking to develop a safer more reliable and accurate insulin infusion device. The Irvine, CA-based company has closed on $2.9 million in a seed financing to help get its SteadiSet infusion set on the market.

The series seed financing involved several Angel groups, including Tech Coast Angels, New York Angels, HBS Alumni Angels of New York, Pasadena Angels and the Mass Medical Angels, making the financing one of the broadest and most successful syndications among Angel investor groups. Other investors included the ACE Fund, PA Fund and NYA Fund.

Financing proceeds will be used for clinical trials and to file a submission with FDA.

“We’re testing [our device] in animals at Thomas Jefferson University and we’re now preparing for our first human clinical work and getting on to the commercialization pathway with the 510(k) clearance,” Paul Strasma CEO and Co-founder of Capillary Biomedical, told MD+DI. “We’re looking to be on the market in late 2019.”

The core cannula technology was developed by Jeffery Joseph at the Jefferson Artificial Pancreas Center of Thomas Jefferson University with grant funding from the National Institutes of Health and JDRF, the leading global organization funding Type 1 diabetes research.

Strasma said there would be additional funding as the product began moving through the regulatory cycle.

“The follow-on series A round will be to support commercial and manufacturing scale up during launch,” Strasma said.

Hands-On: VRgineers' XTAL Headset – Enhancing VR for Engineers

The XTAL headset has similar specs to the VRHero 5K, but with new embedded sensor technologies to improve control and image quality. (Image source: VRgineers)

VRgineers—the VR hardware startup focused on creating headsets targeted specifically at engineers and designers in enterprise applications—is now shipping the latest version of its flagship headset. Dubbed the XTAL, the new headset boasts enhanced performance, newly embedded sensor technology, and improved image quality.

Company CEO Marek Polcak had always stressed that the company has placed image quality and fidelity as paramount, to the extent that VRgineers has created its own proprietary lenses with the help of a third-party manufacturer. Polcak remains mostly secretive on this working relationship, but the name of the new headset, XTAL, is short for “crystal.” The name refers to Polcak's obsession with crystal-clear imagery as well as to the lenses featured in the headset, which flaunt a new, crystal-like polygonal structure. The lenses' country of origin is known for the ancient craft of making Bohemian crystal glass, according to Polcak.

Design News had an opportunity to get a hands-on demonstration of the XTAL headset at the company's offices in Los Angeles and found it to be a significant improvement over the previous model, the VRHero 5K—particularly in terms of resolution, image quality, and weight. (Specs would indicate that the XTAL weighs more than the VR Hero, so this is likely due to improved counterbalancing.) The 5K resolution (about 2.5K per eye), 150 to 170-degree field of view, and 70Hz refresh rate of the VRHero 5K are still there. But in the XTAL, all of this is assisted by a new, proprietary feature called AutoEye. Using internal infrared sensors to track the wearer's eyes, XTAL automatically adjusts its lenses to the wearer's interpupillary distance. This, combined with new focus adjustment knobs, creates a sharp viewing experience that even allows users with corrective lenses to forgo their glasses to enjoy the headset. (I've personally found wearing glasses to be a particular annoyance with many VR headsets.)

According to VRgineers, the AutoEye functionality is also open to developers who want to utilize it for functions such as retina detection or eye movement tracking. Doing this allows for eye-tracking-based control schemes as well as graphic features like foveated rendering (i.e., rendering images most clearly at the center of the eye to more closely mimic real-world human vision). This is especially important in enterprise applications such as medical diagnostics and training.

The XTAL's Autoeye feature adjusts the headset's proprietary lenses to the wearer's interpupillary distance to improve image quality. (Image source: VRgineers) 

When we demoed the VRHero 5K earlier this year, it featured the Leap Motion hand-tracking sensor as an external peripheral. With the XTAL, the Leap Motion sensor has now been fully integrated into the headset and offers improved tracking over the previous version of the sensor. Although the software has some issues with tracking the interlocking or inter-positioning of your hands and fingers, the sensor is still highly accurate. It can track individual finger movements with ultra-low latency. Other controllers options—keyboard, mouse, joystick, HTC Vive controller, etc.—are compatible with the XTAL. But Polcak stressed that the hands-only Leap Motion controller, combined with new voice command recognition, provides the preferred methods for giving engineers a natural virtual experience with a low learning curve.

No next-generation VR headset has any business on the market without inside-out tracking to eliminate the need for external sensors. While our demo didn't include the inside-out tracking features, VRgineers said the XTAL is tracking agnostic and is capable of six degrees-of-freedom (6 DoF) inside-out tracking. For complex industrial use cases, the company said the XTAL can currently be combined with third-party, enterprise-grade tracking hardware including AR Tracking, Optitrack, the SteamVR Lighthouse 2.0, Mo-Sys, and Vicon. Those options can be attached as external clip ons to the XTAL to enable 6 DoF tracking. VRgineers is also planning a future software upgrade that will allow for full 6 DoF, inside-out tracking in the headset itself.

ESC, Embedded Systems ConferenceToday's Insights. Tomorrow's Technologies.
ESC returns to Minneapolis, Oct. 31-Nov. 1, 2018, with a fresh, in-depth, two-day educational program designed specifically for the needs of today's embedded systems professionals. With four comprehensive tracks, new technical tutorials, and a host of top engineering talent on stage, you'll get the specialized training you need to create competitive embedded products. Get hands-on in the classroom and speak directly to the engineers and developers who can help you work faster, cheaper, and smarter. Click here to submit your registration inquiry today.

VRgineers has currently partnered with several companies that are using its headsets for design evaluation, virtual prototyping, product development, and other pilot programs. The company currently cites Audi, BMW, and Volkswagen among the automakers that have implemented its headsets into their design engineering workflow. The headset is compatible with several enterprise-grade design software suites including SteamVR (OpenVR), Autodesk VRED, ESI IC.IDO, and design software solutions from Dassault Systèmes.

Going forward, Polcak said the company has its eyes on applying the XTAL beyond VR and into extended reality (XR) as well. No official release date has been announced, but the company plans to introduce a front-facing camera module attachment to the XTAL that will allow for XR and mixed reality (MR) functionality. The XTAL will then be able to detect its external environment to overlay interactive, virtual objects onto the real world and to manipulate real-world objects virtually.

Chris Wiltz is a Senior Editor at Design News covering emerging technologies including AI, VR/AR, and robotics.

Graphene's Conductivity Boosted for Better Solar-Energy Generating Technology

Researchers from the University of Kansas have found yet another use for the versatile material graphene—this time, to help bolster the development of ultra-thin and flexible, highly efficient solar cells. A team from the university’s Department of Physics & Astronomy has paired graphene—a single layer of carbon atoms with high electrical conductivity—with two other atomic layers: molybdenum diselenide (MoSe2) and tungsten disulfide (WS2).

This marriage extends the lifetime of excited electrons in graphene by several hundred times, thus extending the energy possibilities for graphene as a material for electricity generation, Professor Hui Zhao, who led the research, said in a University of Kansas release. “These excited electrons are like students who stand up from their seats—after an energy drink, for example, which activates students like sunlight activates electrons,” he explained. “The energized students move freely in the classroom—like human electric current,” he added.

Graphene already has an excellent charge-transport property, with electrons moving in graphene at a speed of 1/30 of the speed of light. This is much faster than other materials, researchers said, which opens the possibility for graphene to be used in solar cells.

graphene photovoltaic
Researchers from the University of Kansas have connected a graphene layer with two other atomic layers (molybdenum diselenide and tungsten disulfide), thereby extending the lifetime of excited electrons in graphene by several hundred times. (Image source: Matthew Bellus)

Short Life

However, a hindrance to the application of graphene in photovoltaic or photo-sensing devices is the ultra-short lifetime of excited electrons in graphene (referring to the time the electrons stay mobile). In graphene, this time is only one picosecond or one-millionth of one-millionth of a second.

“The number of electrons, or students from our example, who can contribute to the current is determined by the average time they can stay mobile after they are liberated by light,” Zhao said. “In graphene, an electron stays free for only one picosecond. This is too short for accumulating a large number of mobile electrons.”

In other words, he said, though light excitation can move electrons in graphene—and move them quickly—they stay mobile for too short a time to contribute to the generation of electricity. Zhao—working with graduate student Samuel Lane—has solved this problem, basically taking “the chairs away from the standing students so that they have nowhere to sit,” he explained. “This forces the electrons to stay mobile for a time that is several hundred times longer than before.” 

Essentially, the researchers designed a tri-layer material by putting single layers of MoSe2, WS2, and graphene on top of each other. Keeping with the student analogy, the MoSe2 and graphene layers act as two classrooms full of students all sitting, while the middle WS2 layer acts as a hallway separating the two rooms, Zhao explained. When light strikes the sample, it liberates some of the electrons in MoSe2.

“They are allowed to go across the WS2-layer hallway to enter the other room, which is graphene,” he said. “However, the hallway is carefully designed so that the electrons have to leave their seats in MoSe2. Once in graphene, they have no choice but to stay mobile and hence contribute to electric currents, because their seats are no longer available to them.”

Researchers demonstrated their idea by using an ultra-short laser pulse of 0.1 picoseconds to liberate some of the electrons in MoSe2. They then used another ultra-short laser pulse to monitor these electrons as they move to graphene. What they discovered is that the electrons move through the “hallway” in about 0.5 picoseconds (on average) and then stay mobile for about 400 picoseconds. This represents a 400-fold improvement over a single layer of graphene, which researchers also measured in their study.

Their experiments also confirmed that “seats” left in MoSe2 stay unoccupied for the same amount of time. This means that scientists applying their method can control this time, depending on their application, by choosing different “hallway” layers, Zhao said. The work—which researchers plan to continue—paves the way for the use of graphene in novel photovoltaics, potentially adding solar-energy generation to the growing list of applications for graphene, researchers said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.

 

Pacific Design and ManufacturingSAVE THE DATE FOR PACIFIC DESIGN & MANUFACTURING 2019! 
Pacific Design & Manufacturing, North America’s premier conference that connects you with thousands of professionals across the advanced design & manufacturing spectrum, will be back at the Anaheim Convention Center February 5-7, 2019! Don’t miss your chance to connect and share your expertise with industry peers during this can't-miss event. Click here to pre-register for the event today!