A Polyimide membrane with ZnO piezoelectric thin film pressure transducers as a differential pressure liquid flow sensor

Fabrication and characterization of ZnO thin film piezoelectric sensors on a polyimide membrane is presented in this paper. As a test device a differential pressure liquid flow sensor has been fabricated. We discuss new material combinations for the fabrication of the test devices. The pressure sensor membrane is a thin polyimide sheet bonded to a silicon wafer and the sensing material is sputtered ZnO piezoelectric thin film. The fabricated liquid flow sensor has been tested with a piezoelectric micropump for flow rates from 30 μl h-1 to 300 μl h-1 . Stroke volumes of 1 to 10 nl have been measured. The strain in the sensing layer has been modeled and a transverse piezoelectric coefficient of e31,f= -0.294 C m-2 has been extracted

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A replication method of fabrication for micro electro mechanical systems (MEMS) structures is presented, for use as an alternative to silicon processing. UV-curable ORMOCER® sol–gel is used as base material. The basic fabrication process involves deposition and patterning of a sacrificial spacer layer and a combined molding and photolithography step. This method allows creation of free-standing micro-mechanical elements with monolithic integration of high resolution micro-optical structures. Strain due to the shrinkage of the ORMOCER® sol–gel material during processing has been measured using test structures. Possible applications of this fabrication process are optical MEMS devices that incorporate lenses, diffractive optics or waveguides