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DS: Fachverband Dünne Schichten
DS 20: Application of Thin Films
DS 20.4: Talk
Tuesday, March 15, 2011, 11:00–11:15, GER 38
AlN-based microstructures for biocompatible piezo-generation — •Nicola Heidrich1,2, Fabian Knöbber1,2, Vadim Lebedev1, Ram Ekwal Sah1, Oliver Ambacher1,2, and Volker Cimalla1 — 1Fraunhofer-Institute for Applied Solid State Physics, Freiburg, Germany — 2Department of Microsystems Engineering, University of Freiburg, Germany
The aim of this work is to fabricate a biocompatible micro-generator using aluminium nitride (AlN) as piezoelectric material to supply implantable sensors sufficiently with energy, rendering batteries and external power supplies unnecessary. Membranes made from AlN- thin films and silicon nitride (SiN), with diameters of 0.8 to 3 mm were investigated with respect to their material properties, resonant behaviour and power-output in different environments, using internal piezoelectrical and external mechanical excitation of the membranes. The out-of-plane displacement of the surfaces was measured by a laser Doppler vibrometer (LDV) with a precision below 1 pm. It goes to show that tensile stressed membranes almost only generate power at their resonant frequencies well above 50 kHz, while compressive stressed (corrugated) membranes are capable of responding effectively to excitation in the low frequency range, being an appropriate solution for energy harvesting from random body movement. Compared to a single corrugated membrane the peak generated power is increased by almost three orders of magnitude with a 3x4 array of serial and parallel connected membranes.