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Proceedings Paper

AlN-based piezoelectric bimorph microgenerator utilizing low-level non-resonant excitation
Author(s): Stefan Hampl; Volker Cimalla; Tobias Polster; Martin Hoffmann
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Paper Abstract

This work aims for utilizing human ocular motion for the self-sufficient power supply of a minimally invasive implantable monitoring system for intraocular pressure (IOP). With a proven piezoelectric functionality (d33>5 pm/V), nanocrystalline thin films of aluminum nitride (AlN) provide a good capability for micromechanical energy harvesting (EH) in medical applications. Many d31-mode microcantilever architectures are poorly suited for human-induced EH: Resonant mass-spring-damper systems are tested under high, narrow-band excitation frequencies. However, human motions, e.g. vibrations of eyeballs are marked by their low frequency, unpredictable, mainly aperiodic and time-varying signature. Different vibration types and directions are 3-dimensionally superimposed. Saccadic eye movements are favorable for inertial microgenerators because of their high dynamic loading (ω≤1000°/s). Our generator concept (symmetric active/active-parallel-bimorph cantilever) enables a high structural compliance by maximizing the piezoactive volume at very low cantilever thicknesses (<1 μm). An increased length and seismic mass enable an effective excitation by low-level aperiodic vibrations such as saccadic acceleration impulses. Analytic calculations and FEA-simulations investigate the potential distribution and transient response of different bimorph structures (length 200- 1000 μm, width 20-200 μm) on broadband vibrations. First released monomorph and bimorph structures show very low resonant frequencies and an adequate robustness.

Paper Details

Date Published: 5 May 2011
PDF: 11 pages
Proc. SPIE 8066, Smart Sensors, Actuators, and MEMS V, 80661E (5 May 2011);
Show Author Affiliations
Stefan Hampl, Ilmenau Univ. of Technology (Germany)
Volker Cimalla, Fraunhofer Institute for Applied Solid State Physics (Germany)
Tobias Polster, Ilmenau Univ. of Technology (Germany)
Martin Hoffmann, Ilmenau Univ. of Technology (Germany)

Published in SPIE Proceedings Vol. 8066:
Smart Sensors, Actuators, and MEMS V
Ulrich Schmid; José Luis Sánchez-Rojas; Monika Leester-Schaedel, Editor(s)

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