Authors: O. Marina, M.D. Ward and G. Kaduchak
Affilation: Los Alamos National Laboratory, United States
Pages: 485 - 488
Keywords: particle manipulation, ultrasonic, dielectrophoresis
Ultrasonic and dielectrophoretic particle manipulation has been studied for particle trajectory modification and particle trapping in microfluidic channels. We report a new approach of a combination of dielectrophoresis (DEP) and ultrasonic fields to trap and concentrate particles and cells in an aqueous suspension. By simultaneously applying orthogonal fields to the sample, the favorable attributes of each field-based manipulation technique can be utilized. Additionally, the parameter space for sorting particles by intrinsic properties spans both acoustic (density and compressibility) and dielectric properties. The microfluidic channel design is a planar structure with the mounting substrate constructed from PZT to serve as the transduction mechanism for the ultrasonic manipulation field. By allowing a nonuniform active electrode surface at the fluid / PZT interface (as opposed to inserting a continuous ground plane) a dielectrophoretic manipulation field is simultaneously driven at the same frequency. Particle sorting and trapping efficiency against on-chip flow is evaluated. The calculations are based upon boundary value solutions and finite element modeling applied to multilayer geometries with finite source aperture. Two different experimental situations are presented: (i) non-resonant ultrasonic excitation, where the effect of DEP is predominant, and (ii) resonant ultrasonic excitation, where both DEP and ultrasonic forces effect particle mobility.