title: Broadband Energy Harvester Using Non-linear Polymer Spring and Electromagnetic/Triboelectric Hybrid Mechanism.
abstract: Over the years, several approaches have been devised to widen the operating bandwidth, but most of them can only be triggered at high accelerations. In this work, we investigate a broadband energy harvester based on combination of non-linear stiffening effect and multimodal energy harvesting to obtain high bandwidth over wide range of accelerations (0.1 g-2.0 g). In order to achieve broadband behavior, a polymer based spring exhibiting multimodal energy harvesting is used. Besides, non-linear stiffening effect is introduced by using mechanical stoppers. At low accelerations (<0.5 g), the nearby mode frequencies of polymer spring contribute to broadening characteristics, while proof mass engages with mechanical stoppers to introduce broadening by non-linear stiffening at higher accelerations. The electromagnetic mechanism is employed in this design to enhance its output at low accelerations when triboelectric output is negligible. Our device displays bandwidth of 40 Hz even at low acceleration of 0.1 g and it is increased up to 68 Hz at 2 g. When non-linear stiffening is used along with multimodal energy-harvesting, the obtained bandwidth increases from 23 Hz to 68 Hz with percentage increment of 295% at 1.8 g. Further, we have demonstrated the triboelectric output measured as acceleration sensing signals in terms of voltage and current sensitivity of 4.7 Vg-1and 19.7 nAg-1, respectively.
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore.|NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, P. R. China.
authors.forename: Rahul Kumar
authors.initials: RK
authors.lastname: Gupta
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore.|NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, P. R. China.
authors.forename: Qiongfeng
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore.|NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, P. R. China.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Dhakar
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore.|NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore.
authors.forename: Chun Huat
authors.initials: CH
authors.lastname: Heng
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore.|NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, P. R. China.|NUS Graduate School for Integrative Science and Engineering, National University of Singapore, 117456, Singapore.
authors.forename: Chengkuo
authors.initials: C
authors.lastname: Lee