High-Efficiency Mixing Chip with Liquid Flow Actuators Operated by Surface Acoustic Waves

摘要

Surface acoustic wave (SAW) devices can be used as component parts for micro total analysis systems (μTAS) because their structures are very simple. We thus fabricated a mixing chip with liquid flow actuators operated only by SAWs. The chip consists mainly of one Y-type flow channel, two pumps, and one mixer. The pumps are located in the upstream areas of the merging point of the flow channel, and the mixer is located in its downstream area. Additionally, the flow actuators have interdigital transducers (IDTs) to generate the SAWs. The IDTs were fabricated by patterning Al/Cr on a LiNbO_3 substrate, and the flow channel wall was made of the epoxy-based negative resist SU-8. Using the mixing chip, we carried out a mixing experiment with two water solutions of different concentrations using glycerin, and a chemical reaction experiment involving luminol luminescence. Through the experiments, it was found that local and rapid mixing of a continuous liquid flow was possible by using the SAW actuators, and the capability of our fabricated mixing chip as a reactor was demonstrated.