Pressure Decay Testbench for Air Leakage Characterization of Micropumps or Microvalves

Microvalves as components of micropumps have been developed, improved and used in different areas of industrial and medical technology [1, 2]. Reliable active or passive microvalves as standalone components enable a variety of different microfluidic systems and applications by regulating or switching fluid flows [1]. For gas applications such as micro vacuum pumps or micro compressors, the leakage rate is an important parameter for proper functioning of the microfluidic system. In order to improve the performance of valves in relation to the leakage rate, a comprehensive evaluation of the valves is important. Often these low gas flow rates below cm³/min cannot be accurately measured with conventional flow sensors. This paper presents a small and low-cost test rig for measuring gas leakage rates accurately below cm³/min with the pressure decay method. Exemplary results of the leakage rate measurement with the pressure decay method combined with reference measurements of a conventional flow sensor are shown using a silicon micropump with two passive silicon flap valves.