The micropump includes continuous cylindrical separating pipes having at least two alternating stages of pipes of small radius and large radius connected in succession. Each pipe of a large radius has one end as a hot zone, and the opposite end as a cold zone. The pipes alternate straight pipes with a large radius and U-shaped curved pipes with a small radius. The relationship of the large radius (R) to the small radius (r) is in a range of R/r=2 to 10000, while the relationship of the temperature (T2) of a hot zone to the temperature (T1) of a cold zone is T2/T1=1.1 to 3.0. The length and radius measurements of a straight pipe and a U-shaped pipe ensure a given change in temperature of the gas from the temperature of the hot zone to the temperature of the cold zone.