Particle manipulation in a microfluidic channel with an electronically controlled linear piezoelectric array

Ultrasonic standing wave manipulation has been proved to be a simple, robust technology to be integrated in microfluidic systems for a range of applications such as particle filtration and concentration, particle trapping and washing, and sensor enhancement. Here we report recent progress in the design, fabrication and experimental demonstration of an electronically controlled ultrasonic array device used for 1-D manipulation of particles along a microfluidic channel. In a previous paper [1], the particle manipulation feasibility has been demonstrated by a 12 element, 500 µm pitch array device. In this paper, an improved 30-element, 200 µm pitch array device made from PZ26 piezoelectric composite has been fabricated and connected to control electronics. The control system comprises a Xilinx Spartan 3a FPGA development board and bespoke analogue driving circuitry, designed for signal multiplexing for array element excitation. A rectangular capillary forming a half wavelength resonance microfluidic chamber was coupled to the array to make a multilayer planar resonator. Manipulation under electronic control was demonstrated with 10 µm fluorescent microspheres suspended in water.