Comparative Study on Microfluidic Performance of ZnO Surface Acoustic Wave Devices on Various Substrates

Abstract

ZnO thin film-based surface acoustic wave (SAW) devices were fabricated on Si, glass and polyimide (PI) substrates, and their microfluidic performances were compared. The Rayleigh and Sezawa mode waves were observed from the ZnO/Si devices, the Rayleigh and Lamb modes from the ZnO/PI, and only the Rayleigh mode from the ZnO/glass devices. The ZnO/Si devices have the best performance with the highest acoustic streaming velocity of about 10 cm/s and the shortest particle concentration time of less than 10 sec. The ZnO/glass SAW devices deliver comparable performances to that on Si substrate, while the ZnO/PI devices perform not as good as the devices on other two types of substrates due to the large acoustic attenuation, but still can deliver a streaming velocity up to 1.0 cm/s and reasonable particle concentration function with a particle concentration time of ∼70 sec. Owing to its low cost, easy fabrication and compatible with traditional glass-based biochemical analysis systems, ZnO/glass SAW device is believed to have better potential for lab-on-a-chip application.