Characterization of a valveless micropump based on liquid viscosity

The concept, design, and experimental characterization of a novel micropump based on the temperature dependence of liquid viscosity is described. Since the difference in flow resistance generated by local heating of the liquid in narrow channels is used for rectification of the flow, the pump is free from mechanically movable valves while attaining high controllability. Small size is important in making this principle work effectively, as well as reducing the complexity of thermal and fluidic design. An experiment using a prototype device fabricated by silicon-based micromachining demonstrated the linear relationship between flow rate and the duration of heating, and the capability of bi-directional pumping.