A review of vibration-based mems piezoelectric energy harvesters

A review of vibration-based MEMS piezoelectric energy harvesters
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Unformatted text preview: A review of vibration-based MEMS piezoelectric energy harvesters Salem Saadon * , Othman Sidek Collaborative Microelectronic Design Excellence Center (CEDEC), School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang, Malaysia a r t i c l e i n f o Article history: Received 28 November 2009 Accepted 14 July 2010 Available online 5 August 2010 Keywords: PZT Vibration Energy harvesting MEMS a b s t r a c t The simplicity associated with the piezoelectric micro-generators makes it very attractive for MEMS applications, especially for remote systems. In this paper we reviewed the work carried out by research- ers during the last three years. The improvements in experimental results obtained in the vibration-based MEMS piezoelectric energy harvesters show very good scope for MEMS piezoelectric harvesters in the field of power MEMS in the near future. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The exibility associated with piezoelectric materials is very attractive for power harvesting. They possess more mechanical en- ergy for conversion into electrical energy and can also withstand large amounts of strain. Many methods have been reported to improve the harvested power of MEMS micro-generators. One of the methods is by selecting a proper coupling mode of operation. This involves two modes of operation. The first mode called 31 mode, involves the excited vibration force being applied perpendicular to the poling direction (pending beam). And the other is called 33 mode, in which the force is applied on the same side as the poling direction. The two modes 33 mode and 31 mode are as shown in Fig. 1 . Between the two modes, 31 mode is most commonly used. It produces a lower coupling coefficient k , when compared to the 33 mode. The second method for harvested power improvement is by changing the device configuration. This is accomplished by adding multiple pieces of piezoelectric materials to the harvester. The uni-morph cantilever beam configuration is as shown in Fig. 2 c. Johnson et al. [1] demonstrated using this configuration that highest power can be generated under lower excitation fre- quencies and load resistances. Two combinations of bimorph structures are possible: (a) Series type. (b) Parallel type. Series and parallel triple layer bimorph structures represented by Ng and Liao [2,3] are shown in Fig. 2 a and b respectively. The series triple layer bimorph is constructed out of a metallic layer, sandwiched between two piezoelectrics and the piezoelec- tric patches are electrically connected in series. In the case of the parallel triple, which is also sandwiched between two piezoelectric layers bimorph, the piezoelectric materials are connected in parallel....
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