Structure and Mechanism of Micropump Using Thermoresponsive Polymer Actuator.

Abstract

This paper deals with a kind of micromachine based on a polymer gel actuator system. The polymer actuator has many merits in comparison with other actuators. ( 1 ) It is flexible because it is a polymer material. ( 2 ) It is light in weight. ( 3 ) It is easy to make into an arbitrary shape. Among the polymer gel actuators, we propose a micropump using a thermoresponsive polymer gel. This micropump consists of two one-way valves which make use of a high-water-absorbing polymer gel as a blocking ball. The overall size of this micropump prototype is 8 mm in diameter and 14.5 mm in length. Its weight is 3.2 g. A polymer gel actuator is constituted of the poly (vinyl methyl ether) static polymer (PVME). The mechanism of this micropump is as follows. ( 1 ) By heating the PVME, the gel shrinks. Then the volume of the pump chamber increases, resulting in the inflow of liquid from the inlet to the chamber. ( 2 ) By cooling the PVME, the gel swells in the water. Then the volume of the pump chamber decreases resulting the liquid flow the chamber to the outlet. ( 3 ) By repeating the heating and cooling processes, the micropump provides liquid flow from the inlet to the outlet. The micropump was tested, replacing heating by a nichrome wire with electric current, and showed satisfactory responses.