Patent ID: 8794930

Claim:
An apparatus operable to propel a gas, comprising: at least a first layer and a second layer arranged in a stack and means for heating and/or cooling the first and second layers to form a hot layer and a cold layer wherein the cold layer has a lower temperature than the hot layer; and, at least one through hole in the stack; wherein: a surface of each hot layer is exposed in an interior of the through hole; and a surface of each cold layer is exposed in the interior of the through hole; and wherein an entire length of the through hole is up to 10 times of a mean free path of a gas in which the apparatus is immersed and/or is not greater than 1500 nm, and wherein each hot layer has a chamfer facing inward and in a first direction, an angle between the chamfer of each hot layer and a center axis of the through hole being θ 2 ; each cold layer has a chamfer facing inward and in a second direction opposed to the first direction, an angle between the chamfer of each cold layer and the center axis of the through hole being θ 1 .