VALVE-LESS DIFFUSER MICROPUMPS FABRICATED USING THERMOPLASTIC REPLICATION

This paper presents valve-less diffuser micropumps fabricated using th ermoplastic replication. Thermoplastic replication is very suitable fo r a valve-less diffuser pump due to its simple planar geometry. Two di fferent thermoplastic replication methods have been tested: hot emboss ing and injection molding. We use 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 wafe rs. For the injection molding a commercially available compact disc in jection-molding machine (Tooler Alpha MD100) is used to fabricate the diffuser micropumps. The cycle times are extremely short, less than 10 s per disc, and one properly fabricated nickel mold insert can be use d to fabricate more than 10 000 plastic discs. The plastic material co st is about 5 cents per disc. Tested pumps reach a maximum volume flow of 1.2 mi min(-1) and a maximum pump pressure of 16 kPa. (C) 1998 Els evier Science S.A.