title: Harvesting Low-Frequency (<5 Hz) Irregular Mechanical Energy: A Possible Killer Application of Triboelectric Nanogenerator.
abstract: Electromagnetic generators (EMGs) and triboelectric nanogenerators (TENGs) are the two most powerful approaches for harvesting ambient mechanical energy, but the effectiveness of each depends on the triggering frequency. Here, after systematically comparing the performances of EMGs and TENGs under low-frequency motion (<5 Hz), we demonstrated that the output performance of EMGs is proportional to the square of the frequency, while that of TENGs is approximately in proportion to the frequency. Therefore, the TENG has a much better performance than that of the EMG at low frequency (typically 0.1-3 Hz). Importantly, the extremely small output voltage of the EMG at low frequency makes it almost inapplicable to drive any electronic unit that requires a certain threshold voltage (∼0.2-4 V), so that most of the harvested energy is wasted. In contrast, a TENG has an output voltage that is usually high enough (>10-100 V) and independent of frequency so that most of the generated power can be effectively used to power the devices. Furthermore, a TENG also has advantages of light weight, low cost, and easy scale up through advanced structure designs. All these merits verify the possible killer application of a TENG for harvesting energy at low frequency from motions such as human motions for powering small electronics and possibly ocean waves for large-scale blue energy.
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Zi
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|Department of Applied Physics, Chongqing University , Chongqing 400044, China.
authors.forename: Hengyu
authors.initials: H
authors.lastname: Guo
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|State Key Laboratory of Silicon Materials, School of Materials Science & Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University , Hangzhou 310027, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wen
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Min-Hsin
authors.initials: MH
authors.lastname: Yeh
authors.affiliation: Department of Applied Physics, Chongqing University , Chongqing 400044, China.
authors.forename: Chenguo
authors.initials: C
authors.lastname: Hu
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences; National Center for Nanoscience and Technology (NCNST) , Beijing 100083, China.
authors.forename: Zhong Lin
authors.initials: ZL
authors.lastname: Wang
keywords: electromagnetic generator; energy harvesting; low-frequency energy; mechanical energy; triboelectric nanogenerator