EECS Seminar: Acoustic Tweezing and Propulsion

Abstract:  This presentation describes three examples of microtechnology-enabled acoustic transducers for (1) tweezing large particles, including living and growing embryos, (2) ejecting droplets of living cells and solid particles, including semiconductor chips and (3) propelling in liquid and air. Self-focusing acoustic transducers (SFATs) can produce focused ultrasonic beams as well as trapping zones, and SFAT-based tweezers are shown to trap and hold a zebrafish embryo in its growth medium from 17 hours post fertilization (hpf) to 37 hpf under a light-sheet microscope for continuous trapping and imaging, which reveals organ development. An SFAT-based ejector is shown to offer a contactless and damage-less extraction of a single (or a few) human retinal pigment epithelial (RPE) cell(s) from a cell monolayer, with the number of ejected cells controllable through the pulse width applied to the SFAT ejector. Another SFAT-based ejector can eject 0.4-mm-thick square silicon chips with side lengths from 0.7 to 3.1 mm through an embedded microfluidic guiding cover (for semi-automatic loading of silicon chips to the ejection site), delivering silicon chips out of liquid surface onto a nearby plate for pick-and-placement assembly into a two-dimensional chip array. Finally, acoustic propulsion, which will allow navigation without mechanical engines or moving parts, will be described, as in a liquid, the acoustic streaming effect can shoot a liquid jet from SFAT, causing the transducer to move. Propulsion in air is based on a synthetic air jet shot through an orifice (located near a microspeaker) to move the transducer in the opposite direction of the jet flow.

Bio:  Eun Sok Kim received a bachelor's, master's and doctoral degrees from UC Berkeley in 1982, 1987 and 1990, respectively, all in electrical engineering. His doctoral dissertation was on the integrated microphone with LSI CMOS on a single chip. In the fall of 1999, he joined the University of Southern California, where he is currently William M. Hogue Professor at the Ming Hsieh Department of Electrical and Computer Engineering. From spring 1991 to fall 1999, he worked at the Department of Electrical Engineering in the University of Hawaii at Manoa as a faculty member. Previously, he worked at IBM Research Laboratory, San Jose, CA; NCR Corp., San Diego, CA; and Xicor Inc., Milpitas, CA, as a co-op student, design engineer and summer-student engineer, respectively. Kim is an expert in acoustic, piezoelectric and vibration-energy-harvesting MEMS, having published a textbook titled “Fundamentals of Microelectromechanical Systems (MEMS),” about 270 refereed papers, and 20 issued U.S. patents in the field. He is a fellow of the National Academy of Inventors, Institute of Electrical and Electronics Engineers and the Institute of Physics.