A Magnetic/Piezoelectric-Based Thermal Energy Harvester Tien-Kan Chung *a , Ujjwal Shukla b , Chia-Yuan Tseng a , Chin-Chung Chen a and Chieh-Min Wang a a Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan b Department of Mechanical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India ABSTRACT In this paper, we demonstrate a non-contact magnetic/piezoelectric-based thermal energy harvester utilizing an optimized thermal-convection mechanism to enhance the heat transfer in the energy harvesting/converting process in order to increase the power output. The harvester consists of a CuBe spring, Gadolinium soft magnet, NdFeB hard magnets, frame, and piezoelectric PZT cantilever beams. According to the configuration, the energy harvesting/converting process under a temperature-difference is cyclic. Thus, the piezoelectric beams continuously oscillate and subsequently produce voltage responses due to the piezoelectric effect. The maximum voltage response of the harvester under a temperature- difference of 25°C is 16.6 mV with a cycling frequency of 0.58 Hz. In addition, we compare the testing result of the harvester utilizing the new thermal-convection mechanism reported in this paper and using previous thermal-convection mechanism reported elsewhere. According to the comparison, the results show the harvester utilizing the new thermal- convection mechanism has a higher cycling frequency resulting in a higher power output than the previous mechanism. Keywords: Energy Harvester, Power Generator, Piezoelectric, Magnetic, Thermomagnetic, Temperature, Thermal 1. INTRODUCTION To date, wireless sensors network is comprehensively used in all kinds of environmental sensing and monitoring applications [1, 2]. The sensors are used in remote areas where the importance is given towards the use of energy source abundant in nature rather than using batter as the energy source [3]. Some potential energy sources are available and easily harnessed, such as vibrational energy, strain energy, fluidic energy, solar energy, thermal energy. Among these energy sources, the thermal energy source exists in everywhere. Therefore, harnessing the thermal energy becomes an important issue for the wireless sensors network. Recently, researchers utilize thermoelectric generators, one kind of the thermal energy harvesters, to harness the thermal energy to power the wireless sensors [4, 5]. Thermoelectric generators utilizing seebeck effect possesses a high potential for thermal-energy harvesting. However, in general, lots of thermoelectric generators have to be used together in order to have sufficient energy to power a wireless sensor of a wireless sensors network. Thus, utilizing the other energy sources together with the thermal energy source, if possible, would be the best energy solution for the wireless sensors network. More recently, researchers demonstrated novel thermomagneto-mechanical energy harvesters capable of converting a thermal energy to a mechanical energy [6-9]. Chung, et al, modified the thermomagneto-mechanical energy harvesters as a hybrid energy harvester demonstrating thermal, magnetic, and mechanical energy-harvesting approaches [10]. Therefore, Chung’s harvester is able to be a candidate as the best energy solution for the wireless sensors network. However, Chung’s harvester utilizes a non- optimized thermal convection mechanism as the heat transfer mode for the energy harvesting process. Due to this, the harvester has a low and limited cycling frequency resulting in a low power output. Hence, to address this issue, we present a new thermal convection mechanism for the harvester in this paper. *tkchung@nctu.edu.tw; phone +886-3-5712121 ext. 55116; fax +886-3-572-0634 Active and Passive Smart Structures and Integrated Systems 2013, edited by Henry A. Sodano, Proc. of SPIE Vol. 8688, 86880M · © 2013 SPIE · CCC code: 0277-786X/13/$18 doi: 10.1117/12.2009434 Proc. of SPIE Vol. 8688 86880M-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 04/27/2014 Terms of Use: http://spiedl.org/terms