This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric, electromagnetic and electrostatic. Piezoelectric generators employ active materials that generate a charge when mechanically stressed. A comprehensive review of existing piezoelectric generators is presented, including impact coupled, resonant and human-based devices. Electromagnetic generators employ electromagnetic induction arising from the relative motion between a magnetic flux gradient and a conductor. Electromagnetic generators presented in the literature are reviewed including large scale discrete devices and wafer-scale integrated versions. Electrostatic generators utilize the relative movement between electrically isolated charged capacitor plates to generate energy. The work done against the electrostatic force between the plates provides the harvested energy. Electrostatic-based generators are reviewed under the classifications of in-plane overlap varying, in-plane gap closing and out-of-plane gap closing; the Coulomb force parametric generator and electret-based generators are also covered. The coupling factor of each transduction mechanism is discussed and all the devices presented in the literature are summarized in tables classified by transduction type; conclusions are drawn as to the suitability of the various techniques.

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Energy harvesting vibration sources for microsystems applications

Enabling technologies for wireless sensor networks have gained considerable attention in research communities over the past few years. It is highly desirable, even necessary in certain situations, for wireless sensor nodes to be self-powered. With this goal in mind, a vibration based piezoelectric generator has been developed as an enabling technology for wireless sensor networks. The focus of this paper is to discuss the modeling, design, and optimization of a piezoelectric generator based on a two-layer bending element. An analytical model of the generator has been developed and validated. In addition to providing intuitive design insight, the model has been used as the basis for design optimization. Designs of 1 cm3 in size generated using the model have demonstrated a power output of 375 µW from a vibration source of 2.5 m s−2 at 120 Hz. Furthermore, a 1 cm3 generator has been used to power a custom designed 1.9 GHz radio transmitter from the same vibration source.

https://iopscience.iop.org/article/10.1088/0964-1726/13/5/018/pdf

A piezoelectric vibration based generator for wireless electronics

Energy harvesting generators are attractive as inexhaustible replacements for batteries in low-power wireless electronic devices and have received increasing research interest in recent years. Ambient motion is one of the main sources of energy for harvesting, and a wide range of motion-powered energy harvesters have been proposed or demonstrated, particularly at the microscale. This paper reviews the principles and state-of-art in motion-driven miniature energy harvesters and discusses trends, suitable applications, and possible future developments.

/pdf/energy-harvesting-from-human-and-machine-motion-for-wireless-3lsf4oudvo.pdf

Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices

Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes This paper presents a small (component volume 01 cm3, practical volume 015 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data The generator uses four magnets arranged on an etched cantilever with a wound coil located within the moving magnetic field Magnet size and coil properties were optimized, with the final device producing 46 µW in a resistive load of 4 k? from just 059 m s-2 acceleration levels at its resonant frequency of 52 Hz A voltage of 428 mVrms was obtained from the generator with a 2300 turn coil which has proved sufficient for subsequent rectification and voltage step-up circuitry The generator delivers 30% of the power supplied from the environment to useful electrical power in the load This generator compares very favourably with other demonstrated examples in the literature, both in terms of normalized power density and efficiency

/pdf/a-micro-electromagnetic-generator-for-vibration-energy-acpebp9i50.pdf

A micro electromagnetic generator for vibration energy harvesting

The worldwide thirst for portable consumer electronics in the 1990s had an enormous impact on portable power. Lithium ion batteries, in which lithium ions shuttle between an insertion cathode (e.g., LiCoO2) and an insertion anode (e.g., carbon), emerged as the power source of choice for the highperformance rechargeable-battery market. The performance advantages were so significant that lithium ion batteries not only replaced Ni-Cd batteries but left the purported successor technology, nickel-metal hydride, in its wake.1 The thick metal plates of * To whom correspondence should be addressed. J.W.L: e-mail, jwlong@ccs.nrl.navy.mil; telephone, (+1)202-404-8697. B.D.: e-mail, bdunn@ucla.edu; telephone, (+1)310-825-1519. D.R.R.: e-mail, rolison@nrl.navy.mil; telephone, (+1)202-767-3617. H.S.W.: e-mail, white@chem.utah.edu; telephone, (+1)810-585-6256. † Naval Research Laboratory. ‡ UCLA. § University of Utah. 4463 Chem. Rev. 2004, 104, 4463−4492

Three-dimensional battery architectures.

A device is described for generating electrical power from mechanical energy in a vibrating environment. The design utilises an electromagnetic transducer and its operating principle is based on the relative movement of a magnet pole with respect to a coil. The approach is suitable for embedded remote microsystems structures with no physical links to the outside world. Simulation, modelling and test results following fabrication of a first prototype have demonstrated that generation of practical amounts of power within a reasonable space is possible. Power generation of more than 1 mW within a volume of 240 mm3 at a vibration frequency of 320 Hz has been obtained.

Design and fabrication of a new vibration-based electromechanical power generator

Over recent years there has been a growing interest in the field of micro-systems and their applications across a wide range of areas, including sensor-based systems able to operate with full galvanic isolation. This paper details the development of a self-powered system, specifically for sensor applications that can be energised on a test rig by an electromagnetic vibration-powered generator. This enables wireless operation without the use of a battery with a finite service life. The results of two systems designed for remote sensing in condition monitoring applications are discussed. The first system uses a liquid crystal display to provide the system output; the second uses an infra-red link to transmit the data output.

An investigation of self-powered systems for condition monitoring applications☆

An accelerometer fabricated by a combination of screen printing and silicon micromachining is reported. This is the first device of its kind fabricated in this manner. Details of the finite element model (FEM) of the sensor and its method of fabrication are described. Initial results indicate a sensitivity of 16 pC g-1, which compares very favourably with a sensitivity of 0.15 pC g-1 reported for thin-film devices. Experimental results show a good level of agreement with the FEM results. Analysis of the results highlight the need to further improve the mechanical properties and consistency of the thick-film PZT layer.

https://iopscience.iop.org/article/10.1088/0960-1317/10/3/304/pdf

Design and fabrication of a micromachined silicon accelerometer with thick-film printed PZT sensors

A Wireless Self-Powered Micro-System for Condition Monitoring

We describe a technique that allows the simulation of mixed magnetic and electronic circuits. Magnetic components are described in terms of lumped parameter primitive parts, which are interconnected at magnetic `nodes'. Electrical and magnetic variables are treated in exactly the same manner. Methods of modelling hysteresis and eddy current effects are considered. As an example of a mixed system, an active Hall effect current transducer is analysed.

JN Ross

Papers

Design and fabrication of a new vibration-based electromechanical power generator

An investigation of self-powered systems for condition monitoring applications☆

Design and fabrication of a micromachined silicon accelerometer with thick-film printed PZT sensors

A Wireless Self-Powered Micro-System for Condition Monitoring

Simulation of magneto-electronic systems using Kirchhoffian networks