Temperature control of a droplet on disposable type microfluidic system based on a surface acoustic wave device for blood coagulation monitoring

Control of a droplet temperature for monitoring a bio reaction is important. When a droplet is placed on a surface acoustic wave (SAW) propagating surface, the longitudinal wave is radiated into the droplet. This phenomenon is used to a droplet manipulation on the SAW device. Also, an acoustic streaming is caused in the droplet, uniform mixture is possible. The longitudinal wave radiated attenuates in the droplet and then the droplet is heated. Therefore, using the SAW device, droplet manipulation, uniform mixture and temperature control are possible. Those are advantageous to use the Saw device for a digital microfluidic system (DMFS). In this paper, we focused temperature control of the droplet on a disposable type DMFS, which consists of a sensor plate/liquid layer/128YX-LiNbO₃. First, fundamental characteristics are experimentally obtained. Then temperature of a droplet is kept at 37 °C for a blood coagulation monitoring. Finally, an impedance change during the blood coagulation is monitored using an electrochemical sensor, which is fabricated on the disposable type DMFS.