Recently, Wireless Sensor Networks (WSNs) have attracted lot of attention due to their pervasive nature and their wide deployment in Internet of Things, Cyber Physical Systems, and other emerging areas. The limited energy associated with WSNs is a major bottleneck of WSN technologies. To overcome this major limitation, the design and development of efficient and high performance energy harvesting systems for WSN environments are being explored. We present a comprehensive taxonomy of the various energy harvesting sources that can be used by WSNs. We also discuss various recently proposed energy prediction models that have the potential to maximize the energy harvested in WSNs. Finally, we identify some of the challenges that still need to be addressed to develop cost-effective, efficient, and reliable energy harvesting systems for the WSN environment.

Energy harvesting in wireless sensor networks: A comprehensive review

Energy harvesting technologies have been explored by researchers for more than two decades as an alternative to conventional power sources (e.g. batteries) for small-sized and low-power electronic devices. The limited life-time and necessity for periodic recharging or replacement of batteries has been a consistent issue in portable, remote, and implantable devices. Ambient energy can usually be found in the form of solar energy, thermal energy, and vibration energy. Amongst these energy sources, vibration energy presents a persistent presence in nature and manmade structures. Various materials and transduction mechanisms have the ability to convert vibratory energy to useful electrical energy, such as piezoelectric, electromagnetic, and electrostatic generators. Piezoelectric transducers, with their inherent electromechanical coupling and high power density compared to electromagnetic and electrostatic transducers, have been widely explored to generate power from vibration energy sources. A topical review of piezoelectric energy harvesting methods was carried out and published in this journal by the authors in 2007. Since 2007, countless researchers have introduced novel materials, transduction mechanisms, electrical circuits, and analytical models to improve various aspects of piezoelectric energy harvesting devices. Additionally, many researchers have also reported novel applications of piezoelectric energy harvesting technology in the past decade. While the body of literature in the field of piezoelectric energy harvesting has grown significantly since 2007, this paper presents an update to the authors' previous review paper by summarizing the notable developments in the field of piezoelectric energy harvesting through the past decade.

https://iopscience.iop.org/article/10.1088/1361-665X/ab36e4/pdf

A review of energy harvesting using piezoelectric materials: state-of-the-art a decade later (2008–2018)

Due to increased demands for energy and the current limitations of batteries, a future prospective technology are vibration energy harvesters that convert kinetic vibration energy into electrical energy. These energy harvesters have the potential to be used in powering small electronic devices such as measurement equipment in remote or hostile environments where batteries are not a viable option. Current limitations of vibration based energy harvesters is the total available power generated and the frequency at which they effectively collect ambient vibration sources for producing power; this paper aims to review the current techniques that are being employed to enhance the performance of these devices. These techniques have been categorised into amplification techniques, resonance tuning methods and introducing nonlinear oscillations. Before this technology can be used effectively in applications enhancing the performance of ambient vibration energy harvesters needs to be addressed.

/pdf/a-review-on-performance-enhancement-techniques-for-ambient-4nfdzhwduf.pdf

A review on performance enhancement techniques for ambient vibration energy harvesters

Energy harvesting technology may be considered an ultimate solution to replace batteries and provide a long-term power supply for wireless sensor networks. Looking back into its research history, individual energy harvesters for the conversion of single energy sources into electricity are developed first, followed by hybrid counterparts designed for use with multiple energy sources. Very recently, the concept of a truly multisource energy harvester built from only a single piece of material as the energy conversion component is proposed. This review, from the aspect of materials and device configurations, explains in detail a wide scope to give an overview of energy harvesting research. It covers single-source devices including solar, thermal, kinetic and other types of energy harvesters, hybrid energy harvesting configurations for both single and multiple energy sources and single material, and multisource energy harvesters. It also includes the energy conversion principles of photovoltaic, electromagnetic, piezoelectric, triboelectric, electrostatic, electrostrictive, thermoelectric, pyroelectric, magnetostrictive, and dielectric devices. This is one of the most comprehensive reviews conducted to date, focusing on the entire energy harvesting research scene and providing a guide to seeking deeper and more specific research references and resources from every corner of the scientific community.

/pdf/energy-harvesting-research-the-road-from-single-source-to-czdnbdypb5.pdf

Energy Harvesting Research: The Road from Single Source to Multisource.

Additive Manufacturing of Piezoelectric Materials

A review of the vibration energy harvesting literature has been undertaken with the goal of establishing scaling laws for experimentally demonstrated harvesting devices based on electromagnetic transduction. Power density metrics are examined with respect to scaling length, mass, frequency and drive acceleration. Continuous improvements in demonstrated power density of harvesting devices over the past decade are noted. Scaling laws are developed from observations that appear to suggest an upper limit to the power density achievable with current harvesting techniques.

https://iopscience.iop.org/article/10.1088/0964-1726/24/2/023001/pdf

Scaling and power density metrics of electromagnetic vibration energy harvesting devices

This paper reports on a hybrid rotary-translational vibration energy harvesting approach that exploits cycloidal motion to achieve a relatively high power density from an oscillatory kinetic energy harvester operating at frequencies below 10 Hz. The approach uses a rolling magnetic sphere. The rolling motion mechanically amplifies the velocity at which the magnetic pole of the sphere passes a nearby coil transducer, inducing a proportionally larger electro-motive force across the coil. A prototype cycloidal energy harvester is shown to produce a peak power of 201 mW from a host vibration of 500 mg rms at 5.4 Hz.

Hybrid rotary-translational vibration energy harvester using cycloidal motion as a mechanical amplifier

The Australian Defence Science and Technology Organisation (DSTO) is developing a variety of in-situ structural health monitoring (SHM) approaches for potential use in high value platforms across the Australian Defence Force (ADF). The implementation of SHM systems would allow the ADF to move from expensive interval based inspection and maintenance regimes for ageing platforms to more cost-effective condition-based approaches, and therefore reduce aircraft through - life support costs. One critical issue is determining the optimal means of supplying power to these in-situ SHM systems. To address this issue DSTO has developed a bi-axial vibration energy harvesting approach based on a vibrating spherical-mass, magnet and wire-coil transducer arrangement. It is important that the vibration energy harvesting devices themselves are resistant to fatigue and wear related damage as they may need to operate in service for many years. This paper examines work done on mitigating wear effects in vibration energy harvesting devices, with the goal of ensuring device longevity.

Endurance Testing of a Vibration Energy Harvester for Structural Health Monitoring

Some embodiments relate to an energy conversion device, comprising: a casing; an electromagnetic (EM) transducer disposed at one side of the casing; a round magnet disposed in the casing and free to move relative to the casing and the EM transducer in at least two degrees of freedom; and a ferromagnetic object fixed relative to the casing at an opposite side of the casing to the EM transducer and arranged to attract the magnet toward a rest position within the casing. The EM transducer is positioned so that movement of the magnet relative to the EM transducer varies the magnetic field through the EM transducer, thereby generating electrical potential across at least a part of the EM transducer.

Vibration energy harvesting using cycloidal motion

The authors recently reported on a hybrid rotary-translational vibration energy harvesting approach using a spherical permanent-magnet and employing cycloidal motion as a mechanical amplifier. The rotary-translational harvesting approach, which is resonant in nature, can yield approximately twice the e.m.f. compared with a similar translationalonly device. This paper explores the analytic and numerical modelling of the rotary-translational harvester with the goal of finding an efficient method for design optimisation.

Genevieve A. Hart

Papers

Scaling and power density metrics of electromagnetic vibration energy harvesting devices

Hybrid rotary-translational vibration energy harvester using cycloidal motion as a mechanical amplifier

Endurance Testing of a Vibration Energy Harvester for Structural Health Monitoring

Vibration energy harvesting using cycloidal motion

Vibration energy harvesting using a spherical permanent magnet