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Social progress is inseparable from the utilization of energy, signals of extreme consumption of fossil energy and energy crisis appear frequently around the world. Human beings are paying more and more attention to new technologies and the sustainable development of energy collection and conversion. The emergence of piezoelectric, electromagnetic, electrostatic, and triboelectric mechanisms provides a variety of effective methods for new environmental energy collection and conversion technologies. Among them, the piezoelectric–electromagnetic hybrid energy harvester (P-EHEH) has been widely studied due to its high output power, simple structure, and easy miniaturization. Continuous progress has been made in the research of P-EHEH through theoretical exploration, structural optimization, and performance improvement. This Review focuses on the review of P-EHEH at the application level. A detailed introduction summarizes the research status of P-EHEH applied to human body devices, monitoring sensors, and power supply devices, as well as the development status of back-end electronic modules and interface circuits. The future challenges and development prospects of P-EHEH are anticipated. [ABSTRACT FROM AUTHOR]

This paper presents a piezoelectric energy harvesting device applicable to wireless mouse (WM-PEH). Adding magnetic force to the excitation piezoelectric generating unit makes the impact better and more pronounced. The polygonal roller can increase the excitation frequency of the piezoelectric generating unit and broaden the energy collection range and capability of the WM-PEH. The theoretical and simulation analysis of WM-PEH was carried out in this paper. The effects of the length ratio of the exciter rod to the support frame and the circular impact area on the output characteristics of the prototype were discussed in the experiment. When the length ratio of the exciter rod and the support rod is 3:1, the activity increment of the exciter rod is the largest, and the maximum output voltage can reach 42 V and the maximum output power is 22.43 mW when it acts on a circular generator set with a radius of 1.5 mm. The design of the device is highly integrated with the wireless mouse that is widely used, and the piezoelectric energy harvesting mechanism and the wireless mouse are perfectly combined, which provides a scientific basis for the subsequent development of a self-powered wireless mouse. [ABSTRACT FROM AUTHOR]

Harvesting wind energy using piezoelectric materials is expected to be an alternative solution for powering wireless sensing networks. This paper proposed a nonlinear isometric L-shaped cantilever beam type piezoelectric wind energy harvester based on magnetic coupling (L-PWEH). The transducer consists of an array of equidistant L-shaped piezoelectric vibrators that are sealed inside the shell. It greatly improves the equivalent piezoelectric coefficient, robustness, and wind speed range for reliable operation. Theoretical and simulation analyses of the structural parameters related to the widening of the L-PWEH were performed. The prototype was built and the experimental system was constructed to verify the feasibility of the L-PWEH and the results of the analyses. Experiments have shown that increasing the magnetic force, additional springs, and the appropriate quantity of excitation magnets can effectively increase the output voltage and widen the wind speed range at high voltage output. When the wind speed is 16.35 m/s and the load resistance is 2 MΩ, the best output power of the piezoelectric vibrator is 142.3 µW. At this time, the height of the middle excitation magnet of the prototype is 12 mm, the number is 5, and the wire diameter of the additional spring is 1 mm. The prototype can successfully make the electronics work properly. [ABSTRACT FROM AUTHOR]

[Display omitted] • HEH provides new power supply solutions for marine and river monitoring equipment. • Mixed use of PEH and EMH improves prototype output performance. • The use of non-contact magnetism can improve service life. • Prototypes can easily power some commercial sensing electronics. Water contains a great amount of potential energy, out of this, an energy harvesting and converting solution from water is very promising for green renewable energy. In this paper, a hybrid energy harvester (HEH) is proposed, which has a combination of piezoelectric and electromagnetic mechanisms for energy conversion. Two piezoelectric energy harvesters (PEH) and two electromagnetic energy harvesters (EMH) can work synchronously to achieve high-performance output. The structural variables of the prototype are studied and analyzed through the self-designed experimental test system. When the prototype is assembled with optimal structural parameters, the maximum output voltages of a single PEH and EMH are 56.24 V and 1.016 V. The maximum output power of HEH is 22.78mW, which is 21 % higher than that of PEH and 253011 % higher than that of EMH. Subsequent underwater tests and a series of application tests were performed to verify the performance of the HEH, showing that it can easily power some commercially available sensors and small electronic devices. Experimental results show that HEH is promising in wireless self-powering and self-sensing. It provides a new power supply scheme for laying power supply without grid for monitoring equipment in deep sea and ocean environment. [ABSTRACT FROM AUTHOR]

This paper proposes a rotating piezoelectric ambient wind energy harvesting device with wind turbine structure (R-PWEH), which mainly consists of wind turbine, support structure, excitation module, and power generation unit. This paper mainly investigates the effect of wind turbines with a different number of fan blades and units with different shapes of power generation on the performance output of R-PWEH. A series of experimental studies were conducted on the R-PWEH in the wind speed range of 0–20 m/s. In the experimental study at a wind speed of 16 m/s, the maximum voltage output of the R-PWEH was 114.24 V when the wind turbine with 11 fan blades and the rectangular cantilever beam power generation unit was installed. The optimal external load at this point is 8 kΩ and the maximum output power is 36.89 mW. The fastest charging rate for the capacitor at this parameter allows for easy powering of multiple light-emitting diodes for illumination. It has good prospects for development in practical applications, such as the ability to power micro and small sensors. • The wind turbine can better collect wind energy from the environment. • The use of excitation rod improves overall power generation efficiency. • The effects of different cantilever shapes on R-PWEH are analyzed in detail. • Hermetically sealed housing improves overall environmental adaptability. • It can supply power for micro-electronic devices. [ABSTRACT FROM AUTHOR]

Due to the great potential of rotary piezoelectric energy harvesters in environmental monitoring and energy harvesting, a great deal of research has been conducted by scholars. This paper presents a comprehensive review of the recent research progress of rotary piezoelectric energy harvesters in terms of literature background, excitation principles, practical applications and interface circuits. According to the different excitation methods, we divide the rotary piezoelectric energy harvester into centrifugal, impact, tensile (compression), magnetic and compound types, and describe and evaluate the different research results. Meanwhile the current potential applications of rotating piezoelectric energy harvesters can be divided into three categories: wearable devices, vehicle wheels and other applications, and the corresponding research progress is reviewed. Through the review and analysis of different excitation modes, application scenarios and the back-end energy interface circuits, the reference is improved for the design and research of the rotary piezoelectric energy harvester with high output performance. In addition, this paper also proposes future research directions and challenges. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a low frequency non-contact rotary piezoelectric energy harvester excited by magnetic coupling (L-PEH) was proposed. Through the coupling between the magnet inside the rotor driven by rotating motion and the magnet on the piezoelectric plate, the process of rotating motion transforming into electrical energy was realized. The purpose of this paper was to improve the output performance of piezoelectric energy harvester at low frequency by optimizing the magnetic field conditions, so the influence of the number of magnets and the arrangement of magnets on the output performance was studied in detail. A series of theories, simulations and experiments proved that the alternative magnet arrangement (mode 1) could optimize the output performance of the L-PEH. When the arrangement of magnets was mode 1 and the number of magnets was 2, the peak-to-peak voltage of rectangular and circular piezoelectric plates was 182.5 V and 4.4 V at 250r/min. Under the above optimal parameter variables, the L-PEH could generate the maximum output power of 140.45 mW. In addition, the output power generated by the prototype could fully meet the power consumption of low-power electronic equipment such as light-emitting-diodes (LEDs). In general, by changing the number and arrangement of magnets, i.e. optimizing the magnetic field conditions, L-PEH could effectively collect rotational energy and had a good application prospect in the power supply of micro electronic equipment. • The prototype improves the energy harvesting efficiency at low frequencies. • The prototype can power low-power electronic devices. • The effect of changing magnetic field conditions on the performance is discussed. • The optimum output power of the prototype is 140.45 mW. [ABSTRACT FROM AUTHOR]