The application of a plastic diaphragm for a silicon micropump

The authors propose the use of a thin plastic film as a diaphragm for a silicon micropump. The plastic diaphragm allows large elastic deflection comprising a microsystem with corrosion resistant and low coefficient of friction. All aspects exploited through the development of a micropump with further advantages of eliminating several processing steps when compared with microdevices employing silicon as the thin vibrating element. Low viscosity epoxy resigns and 100 μ m polyethylene sticky tapes were used to overcome the relatively poor adhesion characteristics of plastics to silicon. The polyethylene sticky tape provides the weak bond onto a silicon wafer having microstructures fabricated by silicon bulk micromachining process. Type EPOFI 40200029 (Struers) low viscosity epoxy resin was used to obtain excellent sealing and high bonding strength between the silicon substrate and the plastic diaphragm. Low viscosity epoxy led to the deep penetration of the epoxy resulting in good sealing characteristics. The diaphragm and silicon micropump developed were tested with an external pneumatic actuator and showed excellent performance at pressures in the range of 0-30 psi.