Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Design and experiment of hybridized electromagnetic-triboelectric energy harvester using Halbach magnet array from handshaking vibration M. Salauddin, M.S. Rasel, J.W. Kim, Jae Y. Park ⁎ Department of Electronic Engineering, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 139-701, Republic of Korea ARTICLE INFO Keywords: Handshaking vibration Halbach magnet array Hybrid energy harvester Electromagnetic Triboelectric ABSTRACT We have proposed a new design of hybridized electromagnetic-triboelectric energy harvester using Halbach magnet array from handshaking vibration and validated it theoretically and experimentally. The Halbach array helps to enhance the magnetic flux density and reduce the overall volume as well as generate high power at low frequency. In particular, the proposed dual Halbach array allows the concentrated magnetic flux lines to interact with the same coil in a way where maximum flux linkage occurs. To obtain much higher power generation in low amplitude and low frequency vibrations, the proposed harvester was comprised of a Halbach magnet array, sandpaper passed microstructure PDMS, TENG, and magnetic springs. A prototype of the hybridized energy harvester has been fabricated and tested both using a vibration exciter test and by manual handshaking. Under vibration exciter test, the fabricated prototype of hybridized harvester delivered a high output current and power of 2.9 mA and 11.75 mW, respectively, corresponding to a volume power density of 381 W/m 3 under a loading resistance of 1.39 kΩ at 5 Hz resonant frequency and 0.5 g acceleration. It is also capable of delivering output current and power of 2.85 mA and 8.1 mW, respectively, by handshaking vibration. The fabricated hybridized harvester exhibited much higher power density than the recently reported similar works. Our proposed work takes a significant step toward hybrid energy harvesting from human-body-induced motions such as hand- shaking, walking, running and its potential applications in self powered portable electronics. 1. Introduction Eliciting energy from mechanical vibration has pulled much con- centration during the last few years, by reason of its capability in nature, and unlimited lifetime. Although various vibration sources, such as water and wind flow, rotary motion, and human and machine motion generate vibrations of different frequencies and amplitudes, maximum vibrations are of low frequencies and big amplitudes, with a variety of rotational movements in various directions. Generally used skills for energy harvesting from mechanical vibrations are electro- magnetic [1–4], electrostatic [5], piezoelectric [6–8], and triboelectric [9–11] mechanisms, among which electromagnetic and triboelectric generators are the two most suitable approaches. The electromagnetic generator can also work from the relative movement between magnet and coil. Also, the use of a Halbach magnet array in an electromagnetic energy harvester, instead of a single magnet, increases the magnetic flux density, which in turn partially addresses the power generation issues at low frequencies [12,13]. The electrostatic mechanism is based on repeated charge pumping with variable capacitors, while the pie- zoelectric mechanism is based on the reconfiguration of unbalanced dipole moments. Recently, the triboelectric nanogenerator (TENG) has been highlighted, because of its high power and low fabrication cost. The TENG can scavenge the mechanical energy from the contact/se- paration between two triboelectric materials. Despite the continuous improvement of small-scale mechanical energy harvesters, the level of output energy still needs to be improved to meet the requirements of commercial electronic systems, and to further expand their fields of application. By combining two types of mechanical energy scavenging cells, more electricity can be turned out from one mechanical move- ment, which may convene the power desires of a number of portable electronic devices. A hybrid mechanical energy scavenging process may increase the overall output power [14–16]. Zhang et al. proposed a contact-separation mode hybrid energy harvester with implanted planar coil, which is proper to generate strong instantaneous power [17]. Wu et al. introduced a single electrode based hybrid energy harvester, and analyzed the advantages in charging performance [18], while Han et al. proposed a small size magnetic assisted hybrid energy harvester that could be applied as a self-powered tilt-sensing system [19]. In this work, a hybridized electromagnetic-triboelectric energy http://dx.doi.org/10.1016/j.enconman.2017.09.057 Received 17 July 2017; Received in revised form 12 September 2017; Accepted 20 September 2017 ⁎ Corresponding author. E-mail address: jaepark@kw.ac.kr (J.Y. Park). Energy Conversion and Management 153 (2017) 1–11 0196-8904/ © 2017 Published by Elsevier Ltd. MARK