Nanoporous Bi2Te3 thermoelectric based Knudsen gas pump

The first bi-directional thermoelectric based Knudsen pump is made using a multifunctional nanoporous P-type bismuth telluride (Bi2Te3) thermoelectric material. The nanoporous material has been fabricated using a cold pressing and sintering technique under an argon atmosphere. Analysis of the nanoporous thermoelectric shows the average grain size is 680 nm, the pore radius ranges from 205 to 756 nm, and the average pore radius is 434 nm corresponding to a Knudsen number of 0.075 in the transitional flow regime. Gas flow due to the principle of thermal transpiration was demonstrated using a thermal gradient generated by running current through the thermoelectric, and measuring the gas flow rate and pressure. For an input power of 3.32 W, a maximum of 300 Pa pressure and 1.8 mu l min(-1) flow rate was observed. A reduction of the pore size down to 25 nm, and an improvement of the electrical contact resistance should lead to a 16 time increase in the generated pressure, and reduction in the consumed power respectively.