Tuesday, August 22, 2017

Gallium Nitride ‘Tangoes’ with Silicon to Overcome Nature’s Material Limitations

Gallium nitride (GaN) is a material that is used for radio and satellite communications in civil and military applications and in solid-state lighting such as LED bulbs. Researchers are also exploring GaN for use in high power applications such as power grids and electric vehicles. The market for GaN power devices is expected to reach $2.6 billion dollars by 2022. However, GaN is not an earth abundant material and only recently, small diameter GaN substrates have started to become available. Researchers have been growing GaN on foreign substrates for almost 5 decades, but the quality of the grown materials is compromised, especially on the standard microelectronics substrate, silicon (Si), which is over 1000 times cheaper than GaN substrates. The origin of the problem is a classical one: high quality material deposition is usually carried out near 1,000 degrees Celsius, but when dissimilar materials are cooled down to room temperature, their contraction can be disproportionate, resulting in the formation of cracks and material failure. This is exactly what happens when GaN is grown on Si. And because the crack severity depends on the thickness of the layers, the thickest pure and semiconductive GaN layer that can be grown on Si is 4.5 micrometers thick — too thin to provide good use of GaN for high power (kilovolt-scale) applications which require much thicker layers (10 microns or more). 

Scanning electron microscopy image of 
crack-free GaN on Si (19 μm thick at center).
Now researchers at the Integrated Electronics and Biointerfaces Group at UC San Diego led by electrical engineering professor Shadi Dayeh have solved this classical problem of thermal mismatches in the growth of dissimilar materials. In an article published on Aug. 21 in Advanced Materials, they combined fundamental crystal properties of GaN and geometrical effects to deflect strain from the crystal planes that usually crack under stress to the surface facets that can freely expand and contract in response to stress. By doing so, they were able to grow crack-free 19-micron-thick layers of GaN on Si — thicker than what’s needed for high-power applications. In the resulting structures, both GaN and Si had exposed surfaces to enable them to move, twist or “tango” together without cracking despite their thermal mismatch. 

Electrical engineering professor Shadi Dayeh (left) and 
Ph.D. graduate student Atsunori Tanaka (right) 
near the GaN MOCVD facility in the Qualcomm Institute 
at UC San Diego.
Thick layers also allowed the crystal defects — threading dislocations — to reduce from commonly achieved 108 – 109 per centimeter squared on Si to 107. And with the high material quality, Dayeh and his team demonstrated the first vertical GaN switches on Si. “This is the result of nearly four years of diligent efforts by graduate student Atsunori Tanaka, who learned and quickly excelled in the GaN metal organic chemical vapor deposition here at UC San Diego,” said Dayeh. “Our graduate students go through a full cycle of rigorous training in all aspects in electronic materials and devices and are prepared to tackle the greatest challenges in this area. A group of very talented students including Atsunori Tanaka, Woojin Choi, who fabricated the vertical switches, and Renjie Chen, who did the electron microscopy, have teamed up to complete the research,” Dayeh continued. Based on this work, Dayeh received funding in July from the National Science Foundation to realize a monolithically integrated GaN power converter on Si.

The growth, device fabrication and characterization were performed at UC San Diego and the electron microscopy was performed at the Center for Integrated Nanotechnologies (CINT), a Department of Energy Office of Basic Science user facility that provides access to top-of-the-line equipment under a user proposal system.

Friday, August 11, 2017

UC San Diego at RoboCup 2017



Darren Chen, a Ph.D. student in computer science at UC San Diego, had just landed in Japan when he saw ads in the subway for the competition he was going to take part in. "I realized it was a big deal," he said. He might even have panicked a little, he admitted.
In fact, the competition, called the RoboCup, brought more than 10,000 spectators and competitors to Nagoya, Japan at the end of July. The event, which is broadcast on Japanese TV, was celebrating its 20th anniversary. 
Chen was part of a team of Ph.D. students from the Contextual Robotics Institute here at the Jacobs School that was taking part in the event's RoboCup @ Home challenge. It was UC San Diego's first time taking part in the competition.
In the @ Home challenge, 10 universities from around the world compete to complete a series of tasks by programming and training a Toyota Human Support Robot. The UC San Diego team had to sort groceries and help a person carry grocery items.
 In addition, they faced a task to qualify. On the fly, they had to program the Toyota robot to autonomously navigate and map out a room without bumping into people and objects. The robot also had to be able to obey verbal commands in a noisy environment.
But the team's worst foe turned out to be the venue's WiFi. When 10,000 people were using the same radio band, it became difficult for the robot to communicate with other computers quickly.
The researchers enjoyed the experience of participating in the competition, and look forward to continuing to build assistive robots in the future.
In addition to Chen, the team working on the RoboCup @ Home challenge included   Angelique Taylor, Priyam Parashar  and Ruffin White as well master's student Jaskaran Virdi from the research groups of computer science professors Laurel Riek and Henrik Christensen. Christensen is the director of the Contextual Robotics Institute.
More info: http://jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=2268
Two of the UC San Diego Ph.D. students taking part in the competition, as seen by the Toyota robot.

Darren Chen, center, and Angelique Taylor, right, are two Ph.D. students in the research group of Professor Laurel Riek. 

Taylor has some fun with the robots on exhibit at RoboCup.



Wednesday, August 2, 2017

Alum demos 3D avatar from just one 2D picture

Watch Jacobs School alum Iman Sadeghi demonstrating how you can build a 3D avatar from just one 2D picture by using software from Pinscreen, the company where Sadeghi is VP of engineering.
The technology is powered by neural networks and GPUs.
The Pinscreen demo starts around the 50:30 mark.
The 3D avatar can be used in VR environments. It is expressive and reflects different light conditions.

Thursday, July 27, 2017

Smart Glove Turns Sign Language Into Text

video

Engineers at the University of California San Diego have developed a smart glove that wirelessly translates the American Sign Language alphabet into text and controls a virtual hand to mimic sign language gestures. The device, which engineers call “The Language of Glove,” was built for less than $100 using stretchable and printable electronics that are inexpensive, commercially available and easy to assemble.

The glove was created in the lab of nanoengineering professor Darren Lipomi. The lead graduate student on the project, Timothy O'Connor, spoke to 10 News - ABC San Diego about the work. Check out the video clip above.

In addition to decoding American Sign Language gestures, researchers are developing the glove to be used in a variety of other applications ranging from virtual and augmented reality to telesurgery, technical training and defense.

The glove also made an appearance in KPBS, Newsweek, Popular Mechanics, IEEE Spectrum and various other news outlets.

Click here for the full story on the glove -- read more on how it was built, how it works and what's next.

Tuesday, July 18, 2017

One Imaging Agent to Rule Them All

by Heather Buschman, UC San Diego Health


When you have a medical scan, it’s usually an MRI (magnetic resonance imaging), CT (computed tomography) or more recently, PL imaging (photoluminescence). Sometimes it’s all three as your care team works to determine what’s ailing you. That means three different appointments and three different imaging agents — typically nasty-tasting stuff you have to drink in order to sufficiently enhance the imaging signal so that diseased tissue can be distinguished from healthy tissue. Each comes with its own side effects and potential risks.
“What the medical field has long needed is a single imaging agent that will work across multiple imaging systems,” said Adah Almutairi, PhD, associate professor in the Skaggs School of Pharmacy and Pharmaceutical Sciences at UC San Diego.
Almutairi is always one to take up a challenge like that. Her bioresponsive materials lab is known for designing and developing smart polymers, nanoparticles and hydrogels for many innovative medical and research applications. One of Almutairi’s pet interests is in lanthanides, a family of naturally occurring chemicals that intrigued 19th century chemists because, among many other interesting properties, they burn easily in air, fluoresce under UV light and react with most nonmetals.
Inexplicably, scientific interest in lanthanides waned in the 1970s. A couple of years ago, Almutairi took up the mantle to explore how lanthanides do one special thing: convert low energy light into high energy light. She has long believed that her team could take advantage of that property for medical applications.
Almutairi and her team recently developed a new nanoparticle with a lanthanide-based core-shell-shell architecture. The nanoparticle emits light for optical imaging, but also relaxes water molecules for MRI and attenuates X-rays for CT simultaneously. 
Inexplicably, scientific interest in lanthanides waned in the 1970s. A couple of years ago, Almutairi took up the mantle to explore how lanthanides do one special thing: convert low energy light into high energy light. She has long believed that her team could take advantage of that property for medical applications.
Almutairi and her team recently developed a new nanoparticle with a lanthanide-based core-shell-shell architecture. The nanoparticle emits light for optical imaging, but also relaxes water molecules for MRI and attenuates X-rays for CT simultaneously. 



Three in one: the lanthanide nanoparticles can be used for photoluminescence (PL), computed tomography (CT) and magnetic resonance imaging (MRI) simultaneously.
In a study published in Nano Letters, the researchers tested these nanoparticles in “phantom” tissue — a hydrogel system that mimics living tissue in the laboratory. Not only does the nanoparticle work for each imaging type, it works better than each individual imaging agent on its own.
The team is now working to reduce the size of their new imaging nanoparticle so a patient’s kidneys can clear it more easily from the bloodstream.
“The main point of this study is that we overcame an engineering challenge,” said Sha He, a graduate student in the Jacobs School of Engineering at UC San Diego and first author of the new study. “Now we will tweak the design so we can advance this technology to pre-clinical and clinical testing. Our goal is that one day this nanoparticle, or one like it, will allow a patient to complete his or her imaging all at once, reducing the risk and toxicity associated with separate administration of multiple imaging agents.”

Friday, July 14, 2017

Mechanical engineering alumus honored for work on autonomous amphibious vehicle

UC San Diego Jacobs School of Engineering mechanical engineering alumnus Aaron Burmeister (B.S. mechanical engineering 2001) has been selected as one of the nation’s top scientists and engineers of the year by the Assistant Secretary of the Navy for Research Development and Acquisition.

Burmeister is an engineer for Space and Naval Warfare Systems Center Pacific (SSC Pacific). He won the prestigious Dr. Delores M. Etter Top Scientists and Engineers award, in the individual engineer category, for his work developing an autonomous amphibious vehicle.

“It’s challenging because perception, navigation, and control strategies have to change as the vehicle transitions from sea to surf zone to land domains. We have started the effort by developing an autonomy system that can control a commercially available amphibious manned vehicle capable of going up to 45 mph on land or water,” explained Burmeister, in a statement. 

He goes into more detail on the project in a US Navy video by Aaron Lebsack (embedded below).  





Friday, July 7, 2017

Institute for the Global Entrepreneur Hosted First Annual Innovation Award


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Audrey Olsen
On June 14, the Center on Global Transformation (CGT) in partnership with the Institute for the Global Entrepreneur (IGE) hosted the UC San Diego Application Student Innovation Contest for undergraduate students at the Jacobs School of Engineering. Contest submissions were judged by industry experts, including Qualcomm executives and serial tech entrepreneurs. The winning product, by Audrey Olson, was called MatchRest.  It is a mutual accountability software application that matches people with comparable habits and sleep goals and rewarded them for staying and keeping one another on track. For example, a person with the sleep goals of falling asleep before midnight and turning off her computer an hour beforehand would check in with her partner nightly before doing each, and vice versa.  Each user would also have a virtual bedroom showcasing the status of his or her virtual avatar, which could be upgraded or customized more thoroughly as more goals were reached. Audrey won $5,000 in prize money. Second and third place students received $2,000 and $1,000 respectively.
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Jesse Ren
Audrey’s partner in developing the product is Jesse Ren, acomputer science student and a 2016 NSF I-Corps participant. The Institute of Global Entrepreneur’s I-Corps program teaches lean start-up principles that are focused on product/market fit and customer discovery. Next up for the team, they plan on doing initial customer interviews in the fall to help in the development of their minimum viable product (MVP). They are currently working on personal projects (one such project is for UC San Diego's Project-in-a-Box initiative) while studying, applying, and interviewing for full-time post-graduate positions in the software industry.
We reached out to Elizabeth Lyons, Professor at the School of Global Policy, to talk about the contest.
IGE - What is the innovation contest and why hold it now?
EL - The UC San Diego Student Innovation Contest is a contest for undergraduates at the Jacobs School of Engineering (JSoE), who are interested in working on a real-world problem that has not yet been solved; second, expanding their knowledge and capabilities through a hands-on project; and third, the opportunity to win some money. We held the contest for the first time this year because of the important role innovation plays in economic growth and our interest in understanding whether it’s possible to encourage more innovation through contests like this. We also wanted to give JSoE students the opportunity to grow as innovators, and to build more links between the School of Global Policy and Strategy, JSoE, and the Institute for the Global Entrepreneur (IGE).

IGE -  What was it that made the winning team stand out?

EL - The winner of the contest did an outstanding job of building a commercially viable and technologically functional product. All the judges agreed that her application was user-friendly and that her revenue model was compelling. She stood out in how well she took into consideration all aspects of the innovative process. We received a number of submissions that were technologically very compelling or that had the potential to be commercially successful, but only a few that scored well in both areas.

IGE - When is the next challenge and how do teams sign up?

EL - We are currently working on how to proceed with the contest going forward. Our options for the next challenge will depend on the lessons we’re now compiling from the first contest. We’ve received very helpful feedback from many of our contest participants, and we’re also trying to analyze what led some participants to exert more effort than others in the hopes that we can improve on our contest design going forward. We will be sure to announce any upcoming challenges as soon as we’ve finalized the details!