Plasmonic Photothermal Devices for High Speed Microfluidic Actuation and Applications

Dr. Eric P. Y. Chiou
Aerospace and Mechanical Engineering
University of California, Los Angeles

Pulsed laser mirobeams have been used to create disruption and actuation on the microscale and nanoscale. Examples include laser drilling, laser cell surgery, and mixing of fluids in a microchannel. When a laser pulse is focused in a liquid medium (e.g. water), the intense optical field breaks down water molecules and generates heated plasma (electrons and charger ions) within the focal volume. The heat dissipates into the surrounding liquid and induces cavitation bubbles that expand at high speeds, hundreds of m/s, within hundreds of nanoseconds. Through clever engineering design, such ultrafast dynamic phenomenon can be applied for high speed microfluidic devices such as switches and valves that could enable novel functional devices such high speed cell sorters or pumps.

By coupling this photothermal effect with metallic nanostructures, the threshold energy for exciting vapor cavitation bubbles can be greatly reduced due to surface plasmon oscillation. The laser excited bubbles can be guided and patterned by metallic nanostructrues to control fluidic actuation in the nanoscale, which could open up important biomedical applications such as single cell surgery and gene transfection.

Eric Chiou received his Ph.D. degree in Electrical Engineering and Computer Sciences Department from the University of California at Berkeley in 2005. He received his M.S. degree in Electrical Engineering Department in the University of California at Los Angeles in 2004 and B.S. degree in Mechanical Engineering Department from National Taiwan University in Taiwan in 1998. He joined the Mechanical and Aerospace Engineering Department at the University of California at Los Angeles in 2006. His current research interests include BioMEMS, biophotonics, and nanophotonics. His invention of Optoelectronic Tweezers (OET) was selected by the R&D Magnazine and MICRO/NANO Newsletter as the representative of the best 25 micro- and nano-technology of 2006. He has also received the NSF CAREER AWARD in 2008.