Rapid and Controllable Digital Microfluidic Heating Using AlN/Si Rayleigh Surface Acoustic Waves

This paper reports a rapid and controllable digital microfluidic heating system, which is based on a PDMS chamber to hold the liquid and a surface acoustic wave (SAW) device to heat the liquid. Effects of substrate heat dissipation on the temperature stability of SAW heating are studied, and the SAW heating for piezoelectric substrate, sessile droplet and the liquid in PDMS chamber is investigated. Results show that for the sessile droplet, it is difficult to gain a stable temperature at a high power due to significant SAW streaming effects. Whereas the liquid temperate in PDMS chamber can be digitally controlled by the input SAW power and the SAW heating shows good temperature stability and repeatability.