Stretchable, Flexible, Wearable Solar Cells Take Top Prize at Research Expo 2016

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Photo by Erik Jepsen/UC San Diego Publications

Solar cells that are stretchable, flexible and wearable won the day and the best poster award from a pool of 215 at Research Expo 2016 April 14 at the University of California San Diego. The winning nanoengineering researchers aim to manufacture small, flexible devices that can power watches, LEDs and wearable sensors. The ultimate goal is to design and build much bigger flexible solar cells that could be used as power sources and shelter in natural disasters and other emergencies.

Research Expo is an annual showcase of top graduate research projects for the Jacobs School of Engineering at UC San Diego. During the poster session, graduate students are judged on the quality of their work and how well they articulate the significance of their research to society. Judges from industry, who often are alumni, pick the winners for each department. A group of faculty judges picks the overall winner from the six department winners.

This year, in addition to solar cells, judges recognized efforts to develop 3D skeletal muscle on a chip; a better way to alleviate congestion in data center networks; a nano-scale all-optical sensor; fiber optic strain sensors for structural health monitoring; and a way to predict earthquake damage in freestanding structural systems.

Students are chosen both for the quality of their research and their ability to communicate their work clearly, said George Tynan, associate dean of the Jacobs School of Engineering at UC San Diego. “It’s not enough to have great ideas and great solutions,” he said. “You have to be able to communicate the impact of your work.”

Timothy O’Connor, a nanoengineering Ph.D. student in the research group of professor Darren Lipomi, and winner of the overall best poster award, certainly did that during an interview after the poster sessions. “The greatest challenge of our time is the way that we acquire and distribute energy,” he said. “I honestly believe that if the human race doesn’t get a grip on the way in which we do this, we’re going to play the end game for all of us.”

O’Connor is part of a team of researchers in Lipomi’s lab that is working to create extremely cheap but still efficient solar cells that can be printed roll-to-roll, much like a newspaper, and can easily be deployed on everything from solar farms, to buildings, to clothes and even the human body.

To make the solar cells, O’Connor first needed to determine the best recipe to get optimal electronic performance and flexibility in the same material. He and colleagues discovered a series of rules for molecular design that allowed them to develop solar cells capable of producing 1000 microWatts of power over more than 1000 cycles. That is enough to power a digital watch and LEDs, as well as other wearable biomedical devices. By contrast, the lab’s previous version of these cells could only function for five to 10 cycles.

Next steps include producing much larger versions of the cells, which could be used both as shelters and power sources. “You can deploy these solar tarps and provide a canopy, which would protect people from the elements, while at the same time absorbing sunlight and providing power to any electronic equipment below,” O’Connor said. Researchers also are exploring sustainable manufacturing approaches, such as using water as a substrate to print the cells on. “Green chemistry is definitely a focus for us,” O’Connor said.

Other departmental winners were:

Bioengineering Best Poster

Engineered 3D skeletal muscle-on-a-chip as an in vitro tool
Student(s): Gaurav Agrawal
Professor(s): Shyni Varghese
Industry Application Area(s): Life Sciences/Medical Devices & Instruments

Bioengineers have created a 3D model of skeletal muscle on a chip that would allow scientists and physicians to develop physiologically relevant disease models and technology platform for drug discovery as well as to evaluate efficacy of cell transplantation. The model consists of several hydrogel layers encasing microtissue and sensors. The tissue is made of stem cells embedded in an extra-cellular matrix designed with the architectural and structural complexities of native muscle. Researchers grew and maintained the muscle microtissues for 12 days. They developed a method to calculate the contractile stresses in the muscle. The next step is building the system with human-induced pluripotent stem cells, said Gaurav Agrawal, a Ph.D. student in the research group of bioengineering professor Shyni Varghese. He presented the work at Research Expo.

Computer Science and Engineering Best Poster

Fibbing to alleviate congestion in wan and data center networks
Student(s): Ashish Kashinath | Justin Tee | Debjit Roy
Professor(s): George M. Porter
Industry Application Area(s): Internet, Networking, Systems | Software, Analytics

Sometimes a little lying can help make your networks run faster, UC San Diego computer scientists showed at Research Expo this year. Networks are trained to use the lowest-cost paths from node to node, creating congestion in the process. The researchers developed a tool to predict where and when congestion would occur. They then injected fake nodes into the network’s configuration—a technique called fibbing. This leads the networks to avoid routes that are already in use and prevents congestion. The researchers have tested their approach on simulated wide-area networks and data center networks. In these simulations, the networks where fibbing was introduced ran almost twice as fast as those without fibbing.

Electrical and Computer Engineering Best Poster

Plasmonic nanostructures for nano-scale sensing: Path to an all-optical sensor
Student(s): Ashok Kodigala Professor(s): Boubacar Kante | Y. Shaya Fainman Industry Application Area(s): Electronics/Photonics | Materials | Semiconductor

Electrical engineers are taking one more step toward an all-optical integrated sensor that uses less power and is more sensitive than the current state of the art. Ashok Kodigala, a Ph.D. student at the Jacobs School under the supervision of Prof. Boubacar Kante, designed an array for the sensor equipped with metallic nanoparticles, which can be coated with binding agents that will capture bacteria, or toxins, or viruses. The particles are placed in a specific configuration to increase their sensitivity—they are up to 10 times more sensitive than existing sensors. The design can be combined with a laser and a detector to create a fully integrated lab-on-a-chip. Applications range from chemical to biological sensing for the biomedical industry.

Katie Osterday Best Poster Award Mechanical and Aerospace Engine

Evaluation of fiber optic strain sensors for applications in structural health monitoring
Student(s): Benjamin Levi Martins
Professor(s): John B. Kosmatka
Industry Application Area(s): Aerospace, Defense, Security | Civil/Structural Engineering | Energy/Clean technology

Benjamin Martins, the research group of Professor John Kosmatka, assessed the potential of fiber optic strain sensors to assess structural damage in aircraft wings. Current methods to assess damage only work when the aircraft is not in service. By contrast, fiber optic sensors could be built into the wing at minimal additional cost. The sensors are mounted onto a thin fiber optic cable. Martins demonstrated that they could reliably detect damage and performed as well, if not better, than current methods.

Structural Engineering Best Poster

Experimental and numerical studies of freestanding structural systems
Student(s): Christine Wittich
Professor(s): Tara C. Hutchinson
Industry Application Area(s): Civil/Structural Engineering

Electrical transformers, unreinforced masonry walls and even pedestals bearing antique statues have one thing in common: they are freestanding structural systems and their behavior during an earthquake is poorly understood. Christine Wittich, a Ph.D. student in the research group of structural engineering professor Tara Hutchinson has set out to change that. First, she used Light Detection and Ranging, better known as LiDAR, to scan 25 statues and their pedestals in Florence, Italy. She tested models of the statues and their pedestals on a small shake table at the Powell Structural Research Laboratory here at the Jacobs School. Wittich used the data from the tests to develop a computer model that would predict how freestanding structural systems would behave during an earthquake. This is particularly challenging because these systems fail in many different ways: they slide and rotate and jump—and more. Also, this is a multiple body problem: the statues move a certain way on top of the pedestals, which move in their own way, and the two interact together. Wittich’s ultimate goal is to relate the physical properties of these structures to their probability of failure, which would allow researchers to identify vulnerable structures and design techniques to protect them.