Diffuser Micropump Structured with Extremely Flexible Diaphragm of 2-µm-thick Polyimide Film

Abstract

A miniaturized diffuser/nozzle micropump with extremely thin (only 2.1 µm in thickness) polyimide (PI) membranes was fabricated on a 60-µm-thick Si wafer using simple photolithography processes. The diameter of the diaphragm was 2 mm, and the chamber depth was 60 µm. The micropump was functioned by deforming the membranes with alternating air pressure. The ethanol flow rate of the micropump was over 400 nl/min at 2.5 Hz with an actuated pressure of 5 kPa. The measured flow rate was relatively higher than those of previously reported micropumps with a similar chamber volume owing to the large deflection (over 40 µm) of the PI membrane. The micropump processing issues of plasma induced damage to the PI membrane during Si chamber etching and the behaviors of the static and dynamic deflections of the PI membrane was also discussed. On the basis of the advantages of photolithography processes and the good performance of the micropump, it is expected that the micropump can be fabricated on silicon integrated circuit chips.