Development of liquid pumping devices using vibrating microchannel walls

In this paper, we propose innovative valveless pumping devices for microfluidic systems. The liquid in the microchannel was transported by generating a traveling wave on the channel wall, which was composed of a piezoelectric Pb(Zr,Ti)O-3 (PZT) thin film actuator array. The PZT thin films were deposited on the silicon-on-insulator (501) substrates where microchannels, 200 and 500 mu m wide, were fabricated by deep reactive ion etching (DRIE). The displacement profiles and frequency response of the vibrating wall were measured using a laser Doppler vibrometer. The maximum displacements of the 200 and 500 mu m wide empty channels at 10 V-PP were about 62 and 229 nm, respectively. Minor displacement reductions were observed when the channel was filled with liquid, although the resonant frequencies dropped remarkably. On generating a traveling wave on the channel wall, clear liquid flow could be induced with a mean flow velocity of about 118 and 172 mu m/s for the 200 and 500 mu m wide channels, respectively. (C) 2009 Elsevier B.V. All rights reserved