Microfluidics using the surface tension force in microscale

This review summarizes our on-going effort to establish surface tension as a useful force for MEMS, especially microfluidics. Presented are several examples of using surface tension for microdevices. Droplet ejection mechanism using bubble check valve, pumping with sequential bubbles in microchannel, and electrostatic switching of liquid-metal droplet demonstrate how surface tension attenuates liquid movement so effectively in microscale. Liquid pumping using a bubble (or a droplet) under thermal gradient and electrically driving liquid-metal droplets in microchannel demonstrate that surface tension can even be used an an attractive driving force for microactuation.