Patent ID: 7682138

Claim:
A micropump comprising: a chamber; a first opening section including a plurality of sub-opening sections, each of the sub- opening sections being for connecting the chamber with a first fluid transferring portion, the sub-opening sections having an effective sectional area smaller than that of the first fluid transferring portion and showing, as a whole, a first flow channel resistance that changes depending on change in differential pressure between the chamber and the first fluid transferring portion; a second opening section for connecting the chamber with a second fluid transferring portion, the second opening section having an effective sectional area smaller than that of the second fluid transferring portion, the second opening section showing a second flow channel resistance that changes depending on change in differential pressure between the chamber and the second fluid transferring portion, wherein the differential pressure dependency of the first flow channel resistance is smaller than that of the second flow channel resistance; and a thin plate combined to the chamber; a driving circuit adapted to drive the thin plate so that a volume of the chamber is rapidly reduced and then a volume of the chamber is gradually restored to transfer a liquid in one direction and a volume of the chamber is gradually decreased and then a volume of the chamber is rapidly restored to transfer a liquid in the other direction.