Hybrid Energy Harvesters: Toward Sustainable Energy Harvesting

Abstract

systems and makes them inconvenient for users. [9][10][11] In addition, the periodic exchange of the primary battery causes an enormous waste of resources and complex maintenance problems. [12][13][14] Although the ultralow power consumption system and the high capacity battery can extend the WSN system's operation time, it cannot ensure continuous operation of the system for decades. [15] Thus, an energy harvesting system that converts wasted ambient environment energy into valuable electric energy is one of the important technologies for a future sustainable society. [16][17][18] There are various energy harvesting systems, such as piezoelectric, [19][20][21][22] triboelectric, [23][24][25] thermoelectric, [26][27][28][29][30][31] pyroelectric, [32][33][34] photovoltaic, [35][36][37] and water evaporation-based energy harvesting systems [38,39] and those using green energy sources such as solar, wind, wave, heat, and vibrations. These renewable energy harvesting systems have been receiving great attention in the field of research into renewable and sustainable energy harvesters (EHs) to realize self-powering smart WSN systems and self-charging electronics. [40][41][42][43][44][45][46] The output performance of energy harvesting systems has rapidly improved, and WSN systems and energy harvesting systems have been combined. These two advancements have resulted in extend operation times of small electronic devices. Specialized EH, which uses one kind of green energy, is efficiently converting energy, but this system is fatally flawed because it is influenced by weather conditions. For example, biomechanical energy-based harvesters can generate energy both indoor and outdoors, but specific targeted biomechanical movement is required. [47] Thus, unexpected mechanical energy or other thermal and solar energy is wasted. Similarly, solar EHs can effectively harvest energy under illumination from the sun, but constantly changing weather conditions place constraints on solar cell performance. [48] Furthermore, thermal energy generated by mechanical energy or solar energy is wasted without additional thermal EHs. [49] Therefore, to prevent the useless wasting of energy by a single energy harvesting system, utilizing plural green energy harvesting systems is a countermeasure for sustainable energy harvesting, so that otherwise wasted energy is fully utilized with high energy conversion efficiency, which can power WSN systems at anytime, anywhere.Nature and artificial energies, such as solar, wind, wave, heat, machine vibration, automobile noise continuously exist, so Recently, sustainable green energy harvesting systems have been receiving great attention for their potential use in self-powered smart wireless sensor network (WSN) systems. In particular, though the developed WSN systems are able to advance public good, very high and long-term budgets will be required in order to use them to supply electrical energy through temporary batteries or connecting power cables. This report summarizes recent significant progress in ...

Progress in wearable electronics/photonics—Moving toward the era of artificial intelligence and internet of things

“…Energy harvesting technologies have received rapid development in the past decade, including the widely adopted piezoelectric, electromagnetic, electrostatic, triboelectric, thermoelectric, pyroelectric, photovoltaic transducing mechanisms, and so on. In the field of flexible wearable electronics, thermoelectric, 213 piezoelectric, 214‐216 triboelectric, 217‐219 photovoltaic, 220 and their hybrid mechanisms 221 are commonly adopted due to the good compatibility. Briefly speaking, thermoelectric energy harvesters/generators are based on the Seebeck effect of thermoelectric materials to generate electricity under an existing temperature gradient, such as that between the human body and the ambient environment.…”

A wearable noncontact free‐rotating hybrid nanogenerator for self‐powered electronics

“…10,11 Fortunately, energy harvesting technologies and devices have demonstrated the unique capabilities in powering information electronics, such as nanogenerators, electromagnetic generators (EMGs), and biofuel cells. [12][13][14][15][16] As a new type of renewable, sustainable energy technology, nanogenerator has been reported comprehensively since 2006. 17,18 This technology can convert mechanical energy into electrical power based on triboelectric or piezoelectric effects.…”

Integration designs toward new‐generation wearable energy supply‐sensor systems for real‐time health monitoring: A minireview

“…5,19,20,25 The hybrid power supplies consist of two typical devices above. 15,[26][27][28][29] The noninvasive sensors for healthcare can be generally classified as tactile sensors, temperature sensors, gas sensors, sweat sensors, and so on. 9,[30][31][32] Compared with sensors, the power supplies are usually much bulkier, of which flexible miniaturization is more important.…”