Patent ID: 7980828

Claim:
A microelectromechanical (MEM) pump for pumping a gas, comprising: an inlet chamber for receiving the gas; an outlet chamber in thermal communication with a heat source; and a silicon substrate separating the inlet chamber from the outlet chamber, with the silicon substrate comprising a porous silicon region having a plurality of pores which are oriented substantially perpendicular to a first major surface and a second major surface of the silicon substrate and extending between the inlet chamber and the outlet chamber, and with a cross-section dimension of each pore being substantially equal to or smaller than a mean free path length of the gas to pump the gas from the inlet chamber to the outlet chamber in response to a thermal gradient provided along a length of each pore by the heat source, the silicon substrate having a channel formed therethrough to transport the gas from the outlet chamber located on the second major surface of the silicon substrate to the first major surface of the silicon substrate.