Microfluidics and Microacoustics for Miniature Flow Cytometry
S.K. Ravula, D.W. Branch, J. Sigman, P. Clem, G. Kaduchak and I. Brener
Sandia National Laboratories, US
microfluidics, microacoustics, flow cytometry
Flow cytometry is an indispensable tool in clinical diagnostics, for example in cancer, AIDS, infectious disease outbreaks, microbiology, and others. The cost and size of existing cytometers precludes their entry into field clinics, water monitoring, agriculture/veterinary diagnostics, and rapidly deployable biothreat detection. Much of the cost and footprint of conventional cytometers is dictated by the high speed achieved by cells or beads in a hydrodynamically focused stream. This constraint is removed by using ultrasonic focusing in a parallel microfluidic architecture. In this paper, we will describe our progress towards a microfabricated flow cytometer that uses microfabricated planar piezoelectric transducers in microfluidic channels. We used the system to show that we can achieve acoustic levitation and focusing of microparticles loaded in the system. Upon actuation of the PZT at frequencies between 175-250kHz, beads levitated several microns above the channel surface and moved to laterally spaced streams within the microchannel. By increasing the number of patterned top electrodes interfacing with the microfluidic channel, we aim to “phase” the acoustic force between two or more strips of electrodes to achieve more reliable and complicated manipulation of microparticles. This integrated fabrication scheme has the potential to increase functionality and portability while reducing system cost.
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Nanotech 2007 Conference Program Abstract