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

A review of recent research on mechanics of multifunctional composite materials and structures

This paper reviews energy harvesting technology from mechanical vibration. Recent advances on ultralow power portable electronic devices and wireless sensor network require limitless battery life for better performance. People searched for permanent portable power sources for advanced electronic devices. Energy is everywhere around us and the most important part in energy harvesting is energy transducer. Piezoelectric materials have high energy conversion ability from mechanical vibration. A great amount of researches have been conducted to develop simple and efficient energy harvesting devices from vibration by using piezoelectric materials. Representative piezoelectric materials can be categorized into piezoceramics and piezopolymers. This paper reviews key ideas and performances of the reported piezoelectric energy harvesting from vibration. Various types of vibration devices, piezoelectric materials and mathematical modeling of vibrational energy harvestings are reviewed.

A Review of Piezoelectric Energy Harvesting Based on Vibration

Fine count two-ply yarn supercapacitors are constructed from carbon nanotube yarns and polyaniline nanowires. The thread-like supercapacitor possess excellent electrochemical capacity and are very strong and flexible. When being woven or knitted into wearable electronic devices, alone or in combination with conventional textile yarns, the two-ply yarn supercapacitors can be flexed and stretched repeatedly without significant loss of capacitance.

High‐Performance Two‐Ply Yarn Supercapacitors Based on Carbon Nanotubes and Polyaniline Nanowire Arrays

In an effort to eliminate the replacement of the batteries of electronic devices that are difficult or impractical to service once deployed, harvesting energy from mechanical vibrations or impacts using piezoelectric materials has been researched over the last several decades. However, a majority of these applications have very low input frequencies. This presents a challenge for the researchers to optimize the energy output of piezoelectric energy harvesters, due to the relatively high elastic moduli of piezoelectric materials used to date. This paper reviews the current state of research on piezoelectric energy harvesting devices for low frequency (0–100 Hz) applications and the methods that have been developed to improve the power outputs of the piezoelectric energy harvesters. Various key aspects that contribute to the overall performance of a piezoelectric energy harvester are discussed, including geometries of the piezoelectric element, types of piezoelectric material used, techniques employed to match the resonance frequency of the piezoelectric element to input frequency of the host structure, and electronic circuits specifically designed for energy harvesters.

/pdf/energy-harvesting-from-low-frequency-applications-using-33u6ct9j73.pdf

Energy harvesting from low frequency applications using piezoelectric materials

Over the past few decades the use of portable and wearable electronics has grown steadily These devices are becoming increasingly more powerful However, the gains that have been made in the device performance have resulted in the need for significantly higher power to operate the electronics This issue has been further complicated due to the stagnant growth of battery technology over the past decade In order to increase the life of these electronics, researchers have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be prolonged Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user's gait or endurance are avoided These issues have arisen from previous attempts to integrate power harvesting mechanisms into a shoe such that the energy released during a heal strike could be harvested This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised This will be accomplished by replacing the traditional strap of the backpack with one made of the piezoelectric polymer polyvinylidene fluoride (PVDF) Piezoelectric materials have a structure such that an applied electrical potential results in a mechanical strain Conversely, an applied stress results in the generation of an electrical charge, which makes the material useful for power harvesting applications PVDF is highly flexible and has a high strength, allowing it to effectively act as the load bearing member In order to preserve the performance of the backpack and user, the design of the pack will be held as close to existing systems as possible This paper develops a theoretical model of the piezoelectric strap and uses experimental testing to identify its performance in this application

https://iopscience.iop.org/article/10.1088/0964-1726/16/5/036/pdf

Energy harvesting from a backpack instrumented with piezoelectric shoulder straps

Variable displacement, swash-plate controlled, axial-piston pumps are widely used in applications that require high pressure and variable flow rates The pump consists of a rotating barrel assembly that houses several pistons in a circular array A swash-plate is used to control the displacement of the pistons to adjust the output flow of hydraulic fluid As the barrel rotates, the pistons slide along the angled swash-plate and draw oil from the supply and then discharge oil into the high pressure circuit This results in an almost constant output flow rate This paper analyzes the kinematics of a pump based on its geometry dependent characteristics The analysis assumes an idealized case in which there is no oil leakage and the fluid is considered to be incompressible It is revealed through the analysis that the piston displacement and the pump output flow are slightly increased by using a conical barrel Instantaneous and mean flow rate equations are used to describe the output flow characteristics and flow ripple effect The output flow rate ripple profile is found to be a function of both swash-plate angle and the conical barrel angle A term defined as the flow rate uniformity coefficient is used to better quantify the flow ripple phenomenon A frequency analysis is performed on the output flow rate and an additional order is found to be present when using a conical barrel pump versus one with a cylindrical barrel when the pumps have an odd number of pistons Conical barrel piston pumps are found to have a slight increase in piston displacement, velocity, and acceleration relative to the rotating barrel frame of reference over a pump with a cylindrical barrel This translates into an increase in the output flow rate for a conical piston pump under the same operating conditions The conical barrel is also found to have a reduction in the rotational inertia allowing for faster angular acceleration The presence of an extra order from a frequency analysis for a conical pump with an odd number of pistons has the potential to cause unwanted noise or vibration to the structure or components attached to the pump

http://research.me.mtu.edu/abstracts/Parker%20-%20Kinematic%20Analysis%20of%20a%20Variable%20Displacement%20Axial%20Piston%20Pump%20with%20a%20Conical%20Body.pdf

Kinematic Analysis of a Swash-Plate Controlled Variable Displacement Axial-Piston Pump With a Conical Barrel Assembly

Over the past few decades the use of portable and wearable electronics has grown steadily. These devices are becoming increasingly more powerful, however, the gains that have been made in the device performance has resulted in the need for significantly higher power to operate the electronics. This issue has been further complicated due to the stagnate growth of battery technology over the past decade. In order to increase the life of these electronics, researchers have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be prolonged. Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user’s gait or endurance are avoided. This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised. This will be accomplished by replacing the strap buckle with a mechanically amplified piezoelectric stack actuator. Piezoelectric stack actuators have found little use in energy harvesting applications due to their high stiffness which makes straining the material difficult. This issue will be alleviated using a mechanically amplified stack which allows the relatively low forces generated by the pack to be transformed to high forces on the piezoelectric stack. This paper will develop a theoretical model of the piezoelectric buckle and perform experimental testing to validate the model accuracy and energy harvesting performance.© 2007 ASME

Amplified Piezoelectric Stack Actuators for Harvesting Electrical Energy From a Backpack

Over the past few decades the use of portable and wearable electronics has grown steadily. These devices are
becoming increasingly more powerful, however, the gains that have been made in the device performance has resulted in
the need for significantly higher power to operate the electronics. This issue has been further complicated due to the
stagnate growth of battery technology over the past decade. In order to increase the life of these electronics, researchers
have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be
prolonged. Recent developments in the field have led to the design of a number of mechanisms that can be used to
generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy
sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could
disrupt the user's gait or endurance are avoided. These issues have arisen from previous attempts to integrate power
harvesting mechanisms into a shoe such that the energy released during a heal strike could be harvested. This study
develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the
wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that
his or her endurance and dexterity is not compromised. This will be accomplished by replacing the traditional strap of
the backpack with one made of the piezoelectric polymer polyvinylidene fluoride (PVDF). Piezoelectric materials have
a structure such that an applied electrical potential results in a mechanical strain. Conversely, an applied stress results in
the generation of an electrical charge, which makes the material useful for power harvesting applications. PVDF is
highly flexible and has a high strength allowing it to effectively act as the load bearing member. In order to preserve the
performance of the backpack and user, the design of the pack will be held as close to existing systems as possible. This
paper develops a theoretical model of the piezoelectric strap and uses experimental testing to identify its performance in
this application.

Jonathan Granstrom

Papers

Energy harvesting from a backpack instrumented with piezoelectric shoulder straps

Kinematic Analysis of a Swash-Plate Controlled Variable Displacement Axial-Piston Pump With a Conical Barrel Assembly

Amplified Piezoelectric Stack Actuators for Harvesting Electrical Energy From a Backpack

Harvesting of electrical energy from a backpack using piezoelectric shoulder straps