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

The field of power harvesting has experienced significant growth over the past few years due to the ever-increasing desire to produce portable and wireless electronics with extended lifespans. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their limited lifespan, thus necessitating their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of a disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with piezoelectric materials. This article will review recent literature in the field of power harvesting and present the current state of power harvesting in its drive to create completely self-powered devices.

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A review of power harvesting using piezoelectric materials (2003–2006)

Power consumption is forecast by the International Technology Roadmap of Semiconductors (ITRS) to pose long-term technical challenges for the semiconductor industry. The purpose of this paper is threefold: (1) to provide an overview of strategies for powering MEMS via non-regenerative and regenerative power supplies; (2) to review the fundamentals of piezoelectric energy harvesting, along with recent advancements, and (3) to discuss future trends and applications for piezoelectric energy harvesting technology. The paper concludes with a discussion of research needs that are critical for the enhancement of piezoelectric energy harvesting devices.

/pdf/powering-mems-portable-devices-a-review-of-non-regenerative-30r5zxggdp.pdf

Powering MEMS portable devices—a review of non-regenerative and regenerative power supply systems with special emphasis on piezoelectric energy harvesting systems

Autonomous underwater vehicle (AUV) navigation and localization in underwater environments is particularly challenging due to the rapid attenuation of Global Positioning System (GPS) and radio-frequency signals. Underwater communications are low bandwidth and unreliable, and there is no access to a global positioning system. Past approaches to solve the AUV localization problem have employed expensive inertial sensors, used installed beacons in the region of interest, or required periodic surfacing of the AUV. While these methods are useful, their performance is fundamentally limited. Advances in underwater communications and the application of simultaneous localization and mapping (SLAM) technology to the underwater realm have yielded new possibilities in the field. This paper presents a review of the state of the art of AUV navigation and localization, as well as a description of some of the more commonly used methods. In addition, we highlight areas of future research potential.

/pdf/auv-navigation-and-localization-a-review-2aaowbjv0i.pdf

AUV Navigation and Localization: A Review

https://eprints.whiterose.ac.uk/8882/2/EnergHarv_MagSuspFinal.pdf

Energy harvesting from the nonlinear oscillations of magnetic levitation

Recent developments in miniaturized sensors, digital processors and wireless communication systems have many desirable applications. The realization of these applications however, is limited by the lack of a similarly sized power source. Micro-scale concepts to generate electrical power include devices which use the stored energy in fuels to those which harvest energy from the environment. Many proposed power generation systems employ a piezoelectric component to convert the mechanical energy to electrical energy. Of primary importance is the efficiency of power conversion. In this paper, an exact formula is developed that predicts the power conversion efficiency for a device that contains a piezoelectric component. This formula transparently and quantitatively reveals a trade-off effect on efficiency caused by the quality factor and electromechanical coupling factor of the device. In particular, decreasing the structural stiffness leads to the largest gains in efficiency, followed by decreasing the mechanical damping and increasing the effective mass.

https://iopscience.iop.org/article/10.1088/0960-1317/14/5/009/pdf

Efficiency of energy conversion for devices containing a piezoelectric component

In the future, it may be possible to employ large numbers of autonomous marine vehicles to perform tedious and dangerous tasks, such as minesweeping. Hypothetically, groups of vehicles may leverage their numbers by cooperating. A fundamental form of cooperation is to perform tasks while maintaining a geometric formation. The formation behavior can then enable other cooperative behaviors. In this paper, we describe a leader-follower formation-flying control algorithm. This algorithm can be applied to one-, two-, and three dimensional formations, and contains a degree of built-in robustness. Simulations and experiments are described that characterize the performance of the formation control algorithm. The experiments utilized surface craft that were equipped with an acoustic navigation and communication system, representative of the technologies that constrain the operation of underwater autonomous vehicles. The simulations likewise included the discrete-time nature of the communication and navigation.

A leader-follower algorithm for multiple AUV formations

In this two-part paper, the optimization of the electromechanical coupling coefficient for thin-film piezoelectric devices is investigated both analytically and experimentally. The electromechanical coupling coefficient is crucial to the performance of piezoelectric energy conversion devices. A membrane-type geometry is chosen for the study. In part I a one-dimensional model is developed for a membrane composed of two layers, a passive elastic material and a piezoelectric material. The lumped-parameter model is then used to explore the effect of design and process parameters, such as residual stress, substrate thickness, piezoelectric thickness and electrode coverage, on the electromechanical coupling coefficient. The model shows that the residual stress has the most substantial effect on the electromechanical coupling coefficient. For a given substrate material and thickness an optimum piezoelectric thickness can be found to achieve the maximum coupling coefficient. The substrate stiffness affects the magnitude of the maximum coupling coefficient that can be obtained. Electrode coverage was found to be important to electromechanical coupling. The model predicts an optimum electrode coverage of 42% of the membrane area. The model developed in part I formed the basis for the parameters studied experimentally in part II.

https://iopscience.iop.org/article/10.1088/0960-1317/15/10/002/pdf

Optimization of electromechanical coupling for a thin-film PZT membrane: II. Experiment

A model for broadband electrostatic transducers capable of generating and detecting ultrasound in air at megahertz frequencies has been developed. This model uses a lumped parameter approximation to describe a transducer with a grooved backplate and a stretched diaphragm. The mechanical stiffness effects included in the model are compressibility of the air gap separating the diaphragm and the backplate, flexure bending stiffness of the diaphragm, and in‐plane tension forces applied to the diaphragm. A prototype transducer with backplate grooves 200 μm wide and 3.75 μm deep was constructed using micromachining techniques. Measurements of the electrical admittance and transmit sensitivity were made at various polarization voltages and diaphragm tensions. Model predictions of transducer electrical admittance and transmit sensitivity compare well with experimental data. The resonance frequency is predicted within 50 kHz of the nominal measured value near 500 kHz, and model predictions of transmit sensitivity ...

Broadband electrostatic transducers : modeling and experiments

Electrical power for distributed, wireless sensors may be harvested from vibrations in the ambient through the use of electromechanical transducers. To be most useful, the electromechanical transducer should maximize the harvested power by matching its resonant frequency to the strongest vibration amplitude in the source's vibration spectrum. This paper introduces a new frequency tunable mechanism wherein the deformation of the piezoelectric elements is primarily in-plane extension, and bending effects may be neglected. The extensional mode resonator (XMR) is formed by suspending a seismic mass with two piezoelectric sheets. The mechanism is made frequency tunable by an adjustable link that symmetrically pre-tensions both piezoelectric sheets. A prototype XMR has been built and tested that has demonstrated adjustable and repeatable resonant frequency variation from 80 to 235 Hz. The electrical power generated by the XMR is also insensitive to the driving frequency, when the resonant frequency is matched to the driving frequency.

https://iopscience.iop.org/article/10.1088/0964-1726/17/6/065021/pdf

Michael J. Anderson

Papers

Efficiency of energy conversion for devices containing a piezoelectric component

A leader-follower algorithm for multiple AUV formations

Optimization of electromechanical coupling for a thin-film PZT membrane: II. Experiment

Broadband electrostatic transducers : modeling and experiments

A resonant frequency tunable, extensional mode piezoelectric vibration harvesting mechanism