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The triboelectric nanogenerator (TENG) is a recent technology that reforms kinetic energy generation and motion sensing. A TENG comes with variety of structures and mechanisms that make it suitable for wide range of applications and working conditions. Since mechanical vibrations are abundant source of energy in the surrounding environment, the development of a TENG for vibration energy harvesting and vibration measurements has attracted a huge attention and great research interest through the past two decades. Due to the high output voltage and high-power density of a TENG, it can be used as a sustainable power supply for small electronics, smart devices, and wireless sensors. In addition, it can work as a vibration sensor with high sensitivity. This article reviews the recent progress in the development of a TENG for vibration energy harvesting and vibration measurements. Systems of only a TENG or a hybrid TENG with other transduction technologies, such as piezoelectric and electromagnetic, can be utilized for vibrations scavenging. Vibration measurement can be done by measuring either vibration displacement or vibration acceleration. Each can provide full information about the vibration amplitude and frequency. Some TENG vibration-sensing architectures may also be used for energy harvesting due to their large output power. Numerous applications can rely on TENG vibration sensors such as machine condition monitoring, structure health monitoring, and the Internet of things (IoT). [ABSTRACT FROM AUTHOR]

This paper presents study of an electromagnetic vibration energy harvesting configuration that can work effectively at low frequencies. Unlike the conventional form of vibration energy harvesters in which the mass is directly connected to a vibrating frame with spring suspension, in the proposed configuration a permanent magnet mass is allowed to move freely within a certain distance inside a frame-carrying coil and make impacts with spring end stops. The free motion distance allows matching lower vibration frequencies with an increase in the relative amplitude at resonance. Hence, significant power could be generated at low frequencies. A nonlinear mathematical model including impact and electromagnetic induction is derived. Study of the dynamic behaviour and investigation of the system performance is carried out with the aid of case study simulation. The proposed harvester shows a unique dynamic behaviour in which different ways of response of the internal relative oscillation appear over the range of input frequencies. A mathematical condition for the response type at which the higher relative amplitude appears is derived, followed by an investigation of the system resonant frequency and relative amplitude. The resonant frequency shows a dependency on the free motion distance as well as the utilized mass and spring stiffness. Simulation and experimental comparisons are carried out between the proposed harvester and similar conventional one tuned at the same input frequency. The power generated by the proposed harvesting configuration can reach more than 12 times at 11 Hz in the simulation case and about 10 times at 10 Hz in the experimental case. Simulation comparison also shows that this power magnification increases by matching lower frequencies which emphasize the advantages of the proposed configuration for low frequency operation. [ABSTRACT FROM AUTHOR]

This paper presents design, simulation, and experimentation of a novel micro-electromagnetic vibration energy harvester based on free/impact motion. Power harvesting is simply achieved from relative oscillation between a permanent magnet allowed to move freely inside a tube-carrying electrical coil with two end stoppers and directly connected to the vibration source. The proposed harvester with free/impact motion shows a non-resonant behaviour in which the output power continuously increase with the input frequency and/or amplitude. In addition, the allowable free motion permits significant power scavenging at low frequencies. Hence, the proposed harvester is well suited for the applications involved variable large amplitude–low frequency vibrations such as human-powered devices. A nonlinear mathematical model of the proposed harvester including electromagnetic and impact characteristics is derived and used further for a case study model prediction. A unique way of oscillation is observed, in which four modes of magnet/tube relative motion appear over the range of exciting amplitudes and frequencies. Two experiments are conducted on different fabricated prototypes. The first shows the effect of different magnet shapes on the harvesting performance, and the second is carried out to investigate the performance of two different size prototypes with variable large amplitude-low frequency vibrations. A harvester with cylindrical total size of D9 × L12 mm can generate RMS power of 71.8 μW at (2.5 Hz and 5.2 ms −2 ) and 113.3 μW at (3.33 Hz and 12.38 ms −2 ). Another of D7 × L12 mm size can generate RMS power of 28.4 μW at (2.5 Hz and 5.2 ms −2 ) and 82.9 μW at (3.33 Hz and 12.38 ms −2 ). Comparison with some previously fabricated low frequency energy harvesters is made which shows the advantageous of the new harvester in size minimization as well as the significant power raise with the input amplitude. [ABSTRACT FROM AUTHOR]

• Dielectric elastomer (DE) is coupled with TENG to form a hybrid motion energy harvester (DETEG). • TENG prime the DE, and DE amplifies the TENG output. • DE exhibits very high dielectric strength, which enables delivery of higher output voltage than only-TENG. • DETEG is suitable for ultra-high voltage applications. [Display omitted] Dielectric elastomers are effective ambient motion energy harvesters due to their flexibility, high energy density, and their ability to match low frequency unsteady motions. However, the dielectric elastomer generator (DEG) is in reality a charge pump, which requires an external supply of electrical charge to work as an energy harvester. In this work, the DEG is coupled with a contact-mode triboelectric nanogenerator (TENG) to form a hybrid. The TENG autonomously produces charges by contact electrification and the DEG in turn amplifies the electrical output by raising the charges to a higher electrical potential. In addition, dielectric elastomer exhibits dielectric strength two orders of magnitude higher than air, thus enabling delivery of a higher output voltage than that by TENG only. Both the TENG and the DEG converts mechanical motion to electrical energy via capacitance change. This makes them physically compatible for easy integration. We first analyze the coupled system and identify the optimal conditions that maximizes output yield in the shortest amount of time. We found that, the maximum output was realized when the TENG and DEG were excited perfectly out-of-phase for same input frequency. We showed that the DEG is ideally able to amplify the voltage output from TENG that is proportional to the capacitance change ratio of the DEG. By the same token, the maximum power will also be amplified proportionally for a constant current system. Our experiment showed that 260% and 180% DEG capacitance change can produce saturation voltage amplification of 2.7 and 2, respectively. Our work demonstrated dielectric-elastomer-enhanced output of a TENG and presented the optimal conditions for maximal amplification. [ABSTRACT FROM AUTHOR]