PhD Thesis proposal Piezoelectric micro and nano devices for mechanical energy harvesting During the past ten years, research projects on mechanical energy harvesting have been conducted in order to supply low consumption electronic devices, [SHE01], particularly in the USA for military applications. The need for embedded energy sources is also growing in applications such as portable consumer electronics (mobile phones, audio and video players…) and ambulatory medical electronics (hearing aids, pacemakers…). Moreover, the vibrations of industrial machines can be harvested in order to supply wireless remote sensors located in environments where human intervention for maintenance or battery replacement is difficult or dangerous. Piezoelectric materials are better adapted to miniaturisation [SOD04, BEE06] than other classical technologies like electromagnetic or electrostatic generators, which exhibit lower power densities and are more difficult to integrate in micro or nano systems. The potential of piezoelectric devices for mechanical energy harvesting has been demonstrated, but three major difficulties can be identified. In a global approach, it is necessary to act simultaneously on : - the choice of the conversion material (coupling coefficient of the different vibration modes, lifetime...) ; - the design of the vibrating structure (cantilever, membrane…) ; - the optimisation of the electronic harvesting circuit (efficiency, impedance matching...). Three issues will be more particularly addressed : - the potential of a new structure made of piezoelectric nanowires ; - the design of the vibrating structure geometries in order to optimise the spatial distribution of constraints ; - the modelling of the whole system, including both the electromechanical device and the energy harvesting electronics. The study will contain both theoretical and experimental work. The modelling will combine various methods depending on the device and expected precision : analytical, equivalent circuit and finite element. Different prototypes are planned in order to validate the models. This manufacturing work will be performed by partner institutions (namely Ceramics Laboratory of the Ecole Polytechnique Fédérale de Lausanne in Switzerland and Insensor A/S in Danemark) within the European Institute of Piezoelectric Materials and Devices (www.piezoinstitute.com). The electrical and mechanical characterisation of materials and prototypes will be conducted at our laboratory in Blois, using specialised equipment (laser vibrometer, impedance analyser…). Specific instrumentation will be designed to measure the small currents delivered by the micro/nano piezoelectric devices. Requested profile : Masters degree with theoretical and experimental competencies in electronics, electrical engineering, mechatronics, applied physics and/or acoustics. Experience on characterisation and/or modelling of piezoelectric or other electromechanical systems would be appreciated. Laboratory : Ultrasonics and Piezoelectricity Group (Equipe CUP “Caractérisation Ultrasonore et Piézoélectricité”) Tours University, CNRS FRE2448, INSERM U930: www.u930.tours.inserm.fr (formerly known under the name LUSSI - Laboratoire UltrasSons Signaux et Instrumentation – GIP ULTRASONS) Location : Blois, France, within Ecole Nationale d’Ingénieurs du Val de Loire (ENIVL), Rue de la Chocolaterie, BP 3410, 41034 BLOIS cedex Collaborations : Ceramics Laboratory of Ecole Polytechnique Fédérale de Lausanne (EPFL), Insensor A/S Denmark. Contacts : Guylaine POULIN, [email protected], 02 54 55 84 64 Pascal TRAN HUU HUE, [email protected], 02 54 55 84 44 References : [BEE06] S. P. Beeby, M. J. Tudor, N. M. White, Energy harvesting vibration sources for microsystems applications, Measurement Science and Technology, Vol. 17, 2006, pp. 175–195. [SHE01] N. S. Shenck, J. A. Paradiso, Energy scavenging with shoe-mounted piezoelectrics, IEEE Micro, Vol. 21, 2001, pp. 30–42. [SOD04] H. A. Sodano, D. J. Inman, G. Park, A review of power harvesting from vibration using piezoelectric Materials, The Shock and Vibration Digest, Vol. 36, No. 3, May 2004, pp.197–205.