research

Professors Hesselink and Rivas received Precourt Institute seed grants for their energy research
December 2014

Professor Lambertus Hesselink and Assistant Professor Juan Rivas-Davila are two of eight Stanford faculty seed grant recipients. The awards are to assist in new research that promises clean technology and energy efficiency.

Assistant Professor Juan Rivas' and his research team will continue exploration of more energy-efficient power supplies. An initial goal is to provide energy-efficient methods to pasteurize liquids like milk and fruit juice. The team's long-range goal is to revolutionize the design and manufacture of power electronics components. The Precourt Institute for Energy awarded Rivas-Davila's grant.

Professor Lambertus Hesselink's research will assess and design a method to capture heat waste from computers. His team projects that at least 20% of the waste could be recouped, saving $6 million in electricity per day in the U.S. alone. The Precourt Energy Efficiency Center (PEEC) provided this award.

 

Read the full Stanford report article.

Professor Jelena Vuckovic in her Nanoscale and Quantum Photonics Lab
December 2014

Published in a recent article in Scientific Reports, Professor Vuckovic and her team present the inverse design technique. As stated in the introduction, the "inverse design concept is simple and extendable to a broad class of highly compact devices including frequency filters, mode converters, and spatial mode multiplexers."

"Light can carry more data than a wire, and it takes less energy to transmit photons than electrons," said electrical engineering Professor Jelena Vuckovic, who led the research.

In previous work her team developed an algorithm that did two things: It automated the process of designing optical structures and it enabled them to create previously unimaginable, nanoscale structures to control light. Now, she and lead author Alexander Piggott, a doctoral candidate in electrical engineering, have employed that algorithm to design, build and test a link compatible with current fiber optic networks.

 

Read the article in Scientific Reports

Read the Stanford Report article 

Doctoral candidate Linxiao Zhu, Professor Shanhui Fan and research associate Aaswath Raman pictured with photonic radiative cooling material
December 2014

Professor Shanhui Fan and interdisciplinary team members from EE, ME, and Applied Physics, reported this energy-saving breakthrough in the journal Nature. Using a thermal photonic approach, the material reflects sunlight and emits heat, demonstrating new possibilities for energy efficiency. The photonic radiative cooler consists of seven alternating layers of hafnium dioxide (HfO2) and silicon dioxide (SiO2) of varying thicknesses, on top of 200 nm of silver (Ag), which are all deposited on top of a 200-mm silicon wafer.

The ultrathin, multilayered material can help cool buildings, reducing the need for air conditioning.

 

Image: Norbert von der Groebe

image of Professor Shan Wang, Joohong Choi and Adi Gani
November 2014

A team of Stanford University students and faculty has been selected as one of five Distinguished Award Prize winners in the Nokia Sensing XCHALLENGE, a global competition to catalyze breakthrough medical sensing technologies that will ultimately enable faster diagnoses and easier personal health monitoring.

The Stanford team was recognized for developing a hepatitis B blood test that can be analyzed in minutes using the microprocessor in a smart phone.

The current prize recognizes a 12-month effort by four PhD students – mechanical engineers Daniel Bechstein and Jung-Rok Lee, and electrical engineers Joohong Choi and Adi W. Gani – to create a mobile version of a technology that [EE Professor] Wang and other Stanford researchers have been developing for years.

In essence, the researchers graft magnetic nanoparticles onto biological markers. In this case they are interested in two biomarkers. One is the hepatitis B virus, called the antigen. The other is the antibody that fights hepatitis B. The magnetic particles are the homing beacons that allow instruments to track these biomarkers.

 

For the full story, visit engineering.stanford.edu/news

Image credit: Eigen Lifesciences

image of genome compression team
November 2014

A team led by Stanford electrical engineers has compressed a completely sequenced human genome to just 2.5 megabytes – small enough to attach to an email. The engineers used what is known as reference-based compression, relying on a human genome sequence that is already known and available. Their compression has improved on the previous record by 37 percent. The genome the team compressed was that of James Watson, who co-discovered the structure of DNA more than 60 years ago.

"On the surface, this might not seem like a problem for electrical engineers," said Tsachy Weissman, an associate professor of Electrical Engineering. "But our work in information theory is guiding the development of new and improved ways to model and compress the incredibly voluminous genomic data the world is amassing." In addition to Weissman, the team included Golan Yona, a senior research engineer in Electrical Engineering, and Dmitri Pavlichin, a post-doctoral scholar in Applied Physics and Electrical Engineering.

In recording quality scores, DNA sequencers introduce all sorts of imperfections that are collectively considered "noise." Different sequencers have different noise characteristics. Weissman and his team are developing theory and algorithms for processing the quality scores in a way that reduces the noise and at the same time results in significant compression. Counterintuitive as it might sound at first, they are using lossy compression as a mechanism not only for considerable reduction in storage requirements, but also for enhancing the integrity of the data.

"But, in fact, it is quite intuitive," Weissman said. "Lossy compression, when done right, forces the compressor to discard the part of the signal which is hardest to compress, namely, the noise."

 

For the full story, visit engineering.stanford.edu/news/making-personalized-medicine-practical

 

Image credit: Rod Searcey 

image of tiny, sound-powered chip developed by EE
October 2014

Stanford engineers are developing a way to send power – safely and wirelessly – to "smart chips" programmed to perform medical tasks and report back the results.

Their approach involves beaming ultrasound at a tiny device inside the body designed to do three things:

  • convert the incoming sound waves into electricity;
  • process and execute medical commands; and
  • report the completed activity via a tiny built-in radio antenna.

"We think this will enable researchers to develop a new generation of tiny implants designed for a wide array of medical applications," said Amin Arbabian, an assistant professor of electrical engineering at Stanford.

Arbabian's team recently presented a working prototype of this wireless medical implant system at the IEEE Custom Integrated Circuits Conference in San Jose. 

For the full story, visit news.stanford.edu/news

 

Image credit: Arbabian Lab

image of Asst. Professor Ada Poon
October 2014

Ada Poon, a Stanford assistant professor of electrical engineering, is a master at building miniscule wireless devices that function in the body and can be powered remotely. Now, she and collaborators in bioengineering and anesthesia want to leverage this technology to develop a way of studying – and eventually developing treatments for – pain.

Chronic pain costs the economy $600 billion a year and the two most common treatments have significant drawbacks: narcotics are addictive and surgery is costly and carries considerable risks.

"What we will be able to look at is a more natural measure of pain relief," Poon said. They could assess whether a treatment allows mice to return to normal activities by tallying time spent on an exercise wheel or socializing.

This collaboration is one of 22 projects recently funded by the Stanford Bio-X Seed grants, which Carla Shatz, the director of Bio-X, calls the "glue" that brings interdisciplinary teams together. This project is typical, with an electrical engineer, a bioengineer and an anesthesiologist, all of whom are Bio-X affiliates, working together to solve a biomedical problem. Bio-X has so far brought together more than 600 interconnected faculty members from across campus.

"When you combine people with different skills you will come up with something with truly high impact," Clark said.

For the full story, visit news.stanford.edu/news

Image: L.A. Cicero

 

S. Fan
July 2014

Scientists may have overcome one of the major hurdles in developing high-efficiency, long-lasting solar cells – keeping them cool, even in the blistering heat of the noonday Sun.

By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University, has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society’s  new open-access journal Optica.

Solar cells are among the most promising and widely used renewable energy technologies on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the sun into usable electricity.

Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is causesd by solar cells overheating.

Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however – either by ventilation or coolants – would be prohibitively expensive and at odds with the need to optimize exposure to the sun.

For the full story, visit engineering.stanford.edu.

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