Micro throttle pump employing displacement amplification in an elastomeric substrate

Abstract

We report a micro throttle pump (MTP) with enhanced throttling resulting from beneficial deformation of its elastomer substrate. In the MTP reported, this has doubled the effective deflection of the piezo electric (PZT) actuator with a consequent five-fold enhancement of throttling ratio. This mode of throttling has been modelled by finite element method and computational fluid dynamic techniques whose predictions agreed well with experimental data from a throttle test structure; providing typical throttling ratios of 8:1 at low pressures. The improved throttles have been incorporated in a prototype, single PZT, MTP, fabricated with double-depth microfluidics, which pumped both water and a suspension of 5 mu m polystyrene beads at a maximum flow rate of 630 mu1 min(-1) and a maximum back-pressure of 30 kPa at a pumping frequency of 1.1 kHz. This represents an approximate five-fold enhancement of both performance metrics compared to our previous single PZT device.