Bi-directional gas pump driven by a thermoelectric material

The paper describes the first use of a thermoelectric material to create a thermally driven, bi-directional pump with no moving parts using the thermal transpiration effect (called a Knudsen pump). The use of a thermoelectric material to create the temperature gradient increases the efficiency of the pump and enables the design of a bi-directional pump. Pumps using thermal transpiration reported in earlier publications were all uni-directional. This pump achieves high flow rates in both directions, is easy to fabricate, and generates a continuous pneumatic pressure. The measured pump efficiency, 0.035 cm³/min/W, is the highest reported to date for a Knudsen pump.