Seesaw-structured triboelectric nanogenerator for scavenging electrical energy from rotational motion of mechanical systems

This study reports a seesaw-structured triboelectric nanogenerator (S-TENG) for efficiently harvesting electrical energy from rotational motion of mechanical systems. The designed S-TENG with two arms is comprised four contact-pair units with distinctly different triboelectric polarity materials. The generated electric power from the unique structure based on the seesaw system was double at every machine rotation cycle. A magnetically coupled contact mechanism was also utilized to reduce the wear of the polymer material. It was experimentally confirmed that the proposed design significantly improved the reliability and long-term stability in comparison with currently available TENG systems based on the sliding mechanism. In addition, micro-pyramid patterns were formed on the polymer surface to enhance the surface charge density. Through systematic experiments with a variety of operational conditions, an instantaneous maximum output power density of 13.86 W/m(2) was achieved at a rotation speed of 200 rpm under a constant magnetic field strength of 0.2 T. The S-TENG has been demonstrated as a direct power source to drive small electronic devices such as commercial LED arrays and to charge an energy storage unit. This study further expanded the potential applications of the S-TENG to realize the self powered wireless sensor nodes such as structural health and condition monitoring system. (C) 2017 Elsevier B.V. All rights reserved.