Energy harvesting for assistive and mobile applications

Abstract

Technology advances have enabled modification of the size and shape of the electronic components to the microscale, with commensurate scaling down of their power requirements to milliwatts and microwatt range. Consequently, many complex electronic systems and devices such as wearable medical and autonomous devices consume power in the range less than 200 lW, and wireless sensor networks in the range lW to 100 mW are operated on battery power. Due to the salient limitations of battery power, such as longevity of charge and where applicable, the requirement for periodic recharging, possibilities for utilization of autonomous energy sources is critical for operation of such devices. Ambient energy sources, such as vibrations (1 lW to 20 mW), motion (wide range in power outputs), temperature gradient (0.5-10 mW), radiofrequency waves (>180 lW/cm 2 ), light (100 lW/cm 2 to 100 mW/cm 2 ), acoustics (0.003-0.11 lW/cm 2 ), and many other, have the potential to directly power the electronic device. Ambient energy harvesting, when used separately or in conjunction with batteries, will enhance the longevity of equipment operations requiring portable or autonomous power supply. This paper reviews the state of the art in energy-harvesting techniques, power conversion, and characterization of mini-and microscale self-sustaining power generation systems in the range 600 lW to 5 W, specifically focusing on low-power system applications, for personal assistive and mobile technology devices.

Low‐Loss Piezoelectric Single‐Crystal Fibers for Enhanced Magnetic Energy Harvesting with Magnetoelectric Composite

“…The assembled circuit diagram of the LT1302 module is presented in Figure S6 in the Supporting Information. [14] Therefore, to verify the proper operation of the portable electronics, we tested charging a larger supercapacitor (C S = 1 F) from 0 to 2.2 V (corresponding to stored energy of 2.5 J) with the low-loss MME generator, as shown in Figure 5b-ii. However, our MME generator overcame this problem and was eventually successful in charging the supercapacitor.…”

“…The harvested electric output open-circuit voltage (V AC ) signal from the low-loss MME generator located in the lab without any input is shown in inset Figure 6a-i. [14] It is clear that notable electric power could be harvested everywhere using our MME generator, which could be achieved by adapting the loss factors of the piezoelectric constituent. The fundamental and beat frequencies of the signal were 60 and 5.5 Hz, respectively, which clearly indicate the resultant signal induced by the superposition of two or more noise signals.…”

“…[19][20][21][22] The harvesting performance of piezoelectric-based energy harvesters is directly related to the product of the piezoelectric strain constant, d ij and the piezoelectric voltage constant, g ij (the mathematical product of which is called the figure of merit: FOM = d ij × g ij ), under constant applied stress. [9][10][11][12][13][14] When implanting actual energy devices intended to be portable and self-powered, it is necessary to consider integrating the energy harvesting techniques into the products.Nowadays we are surrounded by a low (typically on the order of <1 mT = 10 G) but fixed frequency (50/60 Hz) magnetic noise field almost everywhere. [19,23] This is because the hysteresis (or non-linearity) of the piezoelectric materials is related to losses such as dielectric loss (inverse of electrical quality factor) and mechanical loss (inverse of mechanical quality factor); and consequently, performance degradation of the device.…”

Survey of Energy Harvesting Systems for Wireless Sensor Networks in Environmental Monitoring

“…In this group we distinguish three main phenomena: the piezoelectric, electrostatic, and electromagnetic (magnetic induction) ones. The first two phenomena can be used in the construction of micro-scale generators; the third one is used in generators with significantly larger overall dimensions [11,21]. Analyzing the mechanical structures of EH generators, we can distinguish two dominant structures.…”

Structure–Property Correlation and Harvesting Power from Vibrations of Aerospace Vehicles by Nanocrystalline La–Pb(Ni1/3Sb2/3)–PbZrTiO3 Ferroelectric Ceramics Synthesized by Mechanical Activation

“…These studies related to PNS–PZT were restricted to the compositional powder particles in micrometer‐sized regime . Moreover, extensive research work has been carried out toward development of various mechanisms and devices, but transduction materials are meagerly investigated for their piezoelectric properties for power harvesting …”