A surface acoustic wave-assisted micromixer with active temperature control

Microfluidic mixing is a critical issue in the lab-on-a-chip system, which has been applied in various biomedical research. Recently, acoustic wave-based active micromixers have been applied to increase the mixing efficiency via acoustic streaming. However, along with the acoustic streaming, the acoustic thermal effect will generate additional heat to increase the temperature of the microfluid. In this work, we present an integrated thermal control unit applied to a surface acoustic wave (SAW)-assisted micromixer to address this problem. A metal microwire as the thermal resistance sensor is fabricated under the microchannel to measure the temperature in different conditions, together with the Peltier cooler beneath allowing the active temperature control of the microfluid. For characterization, neutralization reaction and alkaline phosphatase assay were successfully conducted on this device. It shows the integrated thermal control unit applied to a SAW-assisted micromixer is highly effective in temperature-sensitive biomedical research.