Abstract
A valveless/diffuser micropump with a thin polyimide membrane was designed, fabricated using surface micromachining and characterized. The micropump was actuated by deforming the membrane with alternating air pressure. The micropump chamber had the depth of 525 μm, and the diameter was 7 mm. The top side of the chamber was covered by the polyimide membrane with the thickness of 5.4 μm, and the polyimide ftlm was deposited using the spin coating technique. The deflection of membrane was large, and was nearly 200μm at the static air pressure of 10 kPa and 350μm at 30 kPa. The residual stress in the polyimide membrane induced through the fabrication processes was estimated to be 18.9 MPa. The static pressure limit of the membrane prior to fracture was over 200 kPa. The flow rate of water in the micropump reached 310 μl/min with the applied air pressure of 10 kPa at 3 Hz. Based on the advantages of surface micromachining processes and nice mechanical characteristics of polyimide membrane, fabrication of further miniaturized micropumps such as nanoliter-level micropumps using similar fabrication processes may be possible.
