Valve-less diffuser micropumps fabricated using thermoplastic replication

Here we present the first valve-less diffuser micropumps fabricated using thermoplastic replication. Due to its simple planar geometry the valve-less diffuser pump is very suitable for thermoplastic replication. Two different thermoplastic replication methods have been used: hot embossing and injection molding. As mold inserts we used 0.1 and 0.2 mm deep precision milled brass mold inserts and 20 and 80 mu m deep microelectroformed nickel mold inserts defined from deep reactive ion etched (DRIE) silicon wafers. For the injection molding a commercially available Compact Disc injection molding machine (Tooler Alpha MD100) was used to fabricate the diffuser micropumps with extremely short cycle times. One properly fabricated mold insert of nickel can be used to fabricate more than 10000 plastic discs with a cycle time of less than 10 seconds per disc. The plastic material cost is about 5 cents each. Tested pumps reached a maximum volume flow of 1.9 ml/min and a maximum pump pressure of 7.7 kPa.