Fast mixing digital micro-fluids in PDMS microchannel based on surface acoustic wave

Mixing liquid in small volumes is a key operation for the development of micro-fluidic devices. In this paper, a new method for fast mixing digital micro-fluids has been developed. Two orthogonal interdigital transducers were fabricated on a 128° YX-axis-rotated cut LiNbO₃ substrate. Each interdigital transducer was 35 straight finger pairs in a simple repeating patter, 4.32mm aperture, and a wavelength of ¿=144¿m. T-type PDMS micro-channel with 2.5 mm in width and 0.5mm in depth was mounted on the substrate for directing digital micro-fluids. Amplified RF signals were then fed to the IDTs in succession to actuate digital micro fluids along PDMS micro channel. The mixture was characterized using 2¿l water-2¿l red dye digital micro-fluids and 2¿l glycerol-2¿l red dye digital micro-fluids. Mixture performances of the digital micro-fluids were accessed by our developed soft. The results show that the mixture velocity and mixture degree of digital micro-fluids in PDMS micro-channels are greatly improved by help of surface acoustic wave than that by free diffusion.