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May 9, 2005

Nanotechnology grant will support work on new sensor technology

By Tim Stephens

The National Academies Keck Futures Initiative has awarded a $50,000 grant for nanotechnology research to Holger Schmidt, assistant professor of electrical engineering.

Photo: Holger Schmidt

Holger Schmidt

Photo: Tim Stephens

Schmidt will work with Xing Su, a collaborator based in Santa Clara, to develop a new type of sensor technology for medical and biological analysis.

The project is one of 14 to receive competitive seed grants this year from the National Academies Keck Futures Initiative for interdisciplinary research on nanoscience and nanotechnology. The initiative, funded by the W. M. Keck Foundation, aims to stimulate interdisciplinary research at the most exciting frontiers.

The new sensor technology envisioned by Schmidt and Su would enable the optical detection of specific molecules with single-molecule sensitivity using a compact chip-based device. Schmidt's lab has developed integrated optical waveguides with liquid cores, enabling light propagation through tiny volumes of liquids on a chip. Su works with composite nanoparticles that can be used to amplify optical signals through an effect known as surface-enhanced Raman scattering (SERS). The researchers plan to combine the two technologies to create an "integrated biophotonic Raman sensor."

"The basic idea is that if you shine light on a molecule it will vibrate and scatter light in a way that is characteristic for each type of molecule. This scattered light is very weak, but if the molecules are bound to a nanoparticle, the optical signal is amplified enough to be detectable," Schmidt said.

Su has developed a novel type of hybrid inorganic nanoparticles that produce large Raman scattering signals. Schmidt is also collaborating with Jin Zhang, professor of chemistry and biochemistry at UCSC, who is investigating other kinds of nanoparticles, such as silver aggregates.

"One nice thing about our approach is that it works with a variety of nanoparticles," Schmidt said.

The standard apparatus for detecting SERS is a large Raman microscope set up on a laboratory benchtop. With Schmidt's liquid-core waveguides, however, the optical detection apparatus could be integrated into a silicon chip along with the necessary electronics. This approach could lead to low-cost, portable, and highly sensitive biophotonic sensor devices for identifying proteins and other biologically important molecules in small samples.

Schmidt said his collaboration with Su was the result of attending a conference held last year by the Futures Initiative, called "Designing Nanostructures at the Interface between Biomedical and Physical Systems."

"We wouldn't have met otherwise, so I really value this initiative, which is bringing together people from different disciplines to generate these new directions and ideas," Schmidt said.

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