Micropump with improved priming

A micropump comprising:

• a first wafer;
• at least a second wafer bonded to the first wafer to define a pump chamber;
• at least one upstream valve to selectively connect the pump chamber with at least one inlet of the micropump, said upstream valve having a membrane defining an upstream compartment and a downstream compartment, said membrane being pierced by an inlet orifice for the passage of a fluid from one compartment to the other and by an outlet orifice communicating with said downstream compartment, and said downstream compartment being surrounded by a peripheral wall having a nearest part, an intermediate part and a remotest part relative to said inlet orifice;
• at least one downstream valve to selectively connect the pump chamber with at least one outlet of the micropump;
• control means for causing a periodic variation in the volume of said pump chamber;
• and,
• a sealing ring surrounding said inlet orifice and resiliently biased to bear against a valve seat facing said ring;
• said inlet orifice being positioned in the proximity of said nearest part of the peripheral wall so that, during priming of the micropump, the fluid entering the downstream compartment reaches first said nearest part before being led by said intermediate part to said remotest part of the peripheral wall, said outlet orifice being positioned in the proximity of said remotest part of the peripheral wall.