Nanofluidic bubble pump using surface tension directed gas injection

A new concept for liquid manipulation has been developed and implemented in surface-micromachined fluid channels. It is based on the surface tension directed injection of a gas into the liquid flow through micrometer-sized holes in the microchannel wall. The injected gas is directed to an exhaust by a cross-sectional asymmetry of the microchannel and thereby moves minute liquid volumes. Successful pumping experiments were performed with single stroke volumes of tens of picoliters at frequencies around 1 Hz. The minimum actuation pressure is 0.6 bar for a 2-microm channel height, in accordance with theoretical predictions.