Self-contained actuation of phase-change pistons in microchannels

Abstract

An inchworm-like self-contained actuation mechanism for phase-change pistons using a movable thermopneumatic air chamber has been demonstrated. Two phase-change pistons that enclose an air pocket between them have been moved incremental distances by successive melting and solidification of the pistons timed with the expansion and contraction of the air pocket. For a system in which both pistons were wax-based, localized heating of each piston and the air chamber was used to achieve the motion of the assembly. This design used a two-component wax piston that did not coat the microchannel walls. In a separate design a combination of a wax piston with a piston that solidifies at high temperatures was used to eliminate the localized heating requirement for self-contained actuation. This actuation mechanism can be easily integrated on lab-on-a-chip devices for the self-contained pumping of fluid columns.