High-Performance Piezoelectric Energy Harvesters and Their Applications

The last decade has witnessed significant advances in energy harvesting technologies as a possible alternative to provide a continuous power supply for small, low-power devices in applications, such as wireless sensing, data transmission, actuation, and medical implants. Piezoelectric energy harvesting (PEH) has been a salient topic in the literature and has attracted widespread attention from researchers due to its advantages of simple architecture, high power density, and good scalability. This paper presents a comprehensive review on the state-of-the-art of piezoelectric energy harvesting. Various key aspects to improve the overall performance of a PEH device are discussed, including basic fundamentals and configurations, materials and fabrication, performance enhancement mechanisms, applications, and future outlooks.

A comprehensive review on piezoelectric energy harvesting technology: Materials, mechanisms, and applications

A piezoelectric MEMS energy harvester (EH) with low resonant frequency and wide operation bandwidth was designed, microfabricated, and characterized. The MEMS piezoelectric energy harvesting cantilever consists of a silicon beam integrated with piezoelectric thin film (PZT) elements parallel-arranged on top and a silicon proof mass resulting in a low resonant frequency of 36 Hz. The whole chip was assembled onto a metal carrier with a limited spacer such that the operation frequency bandwidth can be widened to 17 Hz at the input acceleration of 1.0 g during frequency up-sweep. Load voltage and power generation for different numbers of PZT elements in series and in parallel connections were compared and discussed based on experimental and simulation results. Moreover, the EH device has a wideband and steadily increased power generation from 19.4 nW to 51.3 nW within the operation frequency bandwidth ranging from 30 Hz to 47 Hz at 1.0 g. Based on theoretical estimation, a potential output power of 0.53 μW could be harvested from low and irregular frequency vibrations by adjusting the PZT pattern and spacer thickness to achieve an optimal design.

/pdf/piezoelectric-mems-energy-harvester-for-low-frequency-14xdsoddm6.pdf

Piezoelectric MEMS Energy Harvester for Low-Frequency Vibrations With Wideband Operation Range and Steadily Increased Output Power

This paper reviews the recent development of available cold storage materials for air conditioning application. According to the type of storage media and the way a storage medium is used, water and ice, salt hydrates and eutectics, paraffin waxes and fatty acids, refrigerant hydrates, microencapsulated phase change materials/slurries and phase change emulsions are separately introduced as suitable energy storage or secondary loop media. Water storage and static ice storage, which are already well-established technologies, have little need for further study. Dynamic ice slurry application is discussed especially for its generation method, relating to the efficiency and reliability of converting water or aqueous solution to ice crystals or ice slurry. Thermal and physicochemical properties of different phase change materials have been summarized including latent heat, thermal conductivity, phase separation, supercooling, and corrosion. Moreover, corresponding solutions for issues of different materials are also discussed. Thermal and hydraulic characteristics of phase change slurries (mainly about clathrate slurries, microencapsulated phase change slurries, and phase change emulsions) are discussed and summarized. In addition, the principle of the sorption cold storage is described and different kinds of working pairs are introduced. Relevant perspectives for commercialization of storage materials are discussed.

Review of cold storage materials for air conditioning application

Abstract Piezoelectric microelectromechanical systems (PiezoMEMS) are attractive for developing next generation self-powered microsystems. PiezoMEMS promises to eliminate the costly assembly for microsensors/microsystems and provide various mechanisms for recharging the batteries, thereby, moving us closer towards batteryless wireless sensors systems and networks. In order to achieve practical implementation of this technology, a fully assembled energy harvester on the order of a quarter size dollar coin (diameter=24.26 mm, thickness=1.75 mm) should be able to generate about 100 μW continuous power from low frequency ambient vibrations (below 100 Hz). This paper reviews the state-of-the-art in microscale piezoelectric energy harvesting, summarizing key metrics such as power density and bandwidth of reported structures at low frequency input. This paper also describes the recent advancements in piezoelectric materials and resonator structures. Epitaxial growth and grain texturing of piezoelectric materials is being developed to achieve much higher energy conversion efficiency. For embedded medical systems, lead-free piezoelectric thin films are being developed and MEMS processes for these new classes of materials are being investigated. Non-linear resonating beams for wide bandwidth resonance are also reviewed as they would enable wide bandwidth and low frequency operation of energy harvesters. Particle/granule spray deposition techniques such as aerosol-deposition (AD) and granule spray in vacuum (GSV) are being matured to realize the meso-scale structures in a rapid manner. Another important element of an energy harvester is a power management circuit, which should maximize the net energy harvested. Towards this objective, it is essential for the power management circuit of a small-scale energy harvester to dissipate minimal power, and thus it requires special circuit design techniques and a simple maximum power point tracking scheme. Overall, the progress made by the research and industrial community has brought the energy harvesting technology closer to the practical applications in near future.

/pdf/a-review-on-piezoelectric-energy-harvesting-materials-21115qr204.pdf

A Review on Piezoelectric Energy Harvesting: Materials, Methods, and Circuits

This paper presents the modeling, fabrication, and characterization of a piezoelectric microelectromechanical systems (MEMS) energy harvester using a d33 piezoelectric mode. A theoretical analysis and an analytical modeling for the d33-mode device were first performed to estimate the output power as a function of the material parameters and device geometry. A PbTiO3 seed layer was newly applied as an interlayer between the ZrO2 and Pb(Zr0.52Ti0.48)O3 (PZT) thin films to improve the piezoelectric property of the sol-gel spin-coated PZT thin film. The fabricated cantilever PZT film with an interdigital shaped electrode exhibited a remnant polarization of 18.5 C/cm2, a coercive field of less than 60 kV/cm, a relative dielectric constant of 1125.1, and a d33 piezoelectric constant of 50 pC/N. The fabricated energy-harvesting device generated an electrical power of 1.1 W for a load of 2.2 M with 4.4 Vpeak-to-peak from a vibration with an acceleration of 0.39 g at its resonant frequency of 528 Hz. The corresponding power density was 7.3 mW cm-3 · g-2. The experimental results were compared with those numerically calculated using the equations derived from the dynamic and analytical modeling. The fabricated device was also compared with other piezoelectric MEMS energy-harvesting devices.

Modeling and Characterization of Piezoelectric $d_{33}$ -Mode MEMS Energy Harvester

A theoretical and experimental study is performed to investigate the characteristics of ice slurry product. By diffusion-controlled evaporation model the possibility of ice slurry is theoretically anticipated. The water vapor evaporated from the surface of droplets is extracted continuously from the chamber by a vacuum pump. The droplet diameter is measured by silicon immersion method. The ice slurry is obtained by spraying droplets of ethylene glycol aqueous solution in the chamber where pressure is maintained under the triple point of water. The droplet with the diameter of 300㎛ and the initial temperature of 20℃ was changed into ice particle within the chamber of 1.33m in height.

A Study on Ice Slurry Production by Water Spray

Provided are an electric power generating apparatus for a movement type equipment and a self-generation system having the same. The electric power generating apparatus for a movement type equipment includes: a piezoelectric beam having an end fixed to a movement type equipment and other end with a mass; and a rectifier unit for rectifying and storing electric energy generated due to deformation of the piezoelectric beam. The self-generation system includes: a movement type equipment; and an electric power generating apparatus for a movement type equipment including a piezoelectric beam having an end fixed to a movement type equipment and other end with a mass, and a rectifier unit for rectifying and storing electric energy generated due to deformation of the piezoelectric beam. According to the electric power generating apparatus for the movement type equipment and the self-generation system having the same, since external movement is converted into vibration perpendicular to an electric beam using elasticity of the electric beam and load applied to an end of the beam, continuous vibration is induced to the piezoelectric beam. Also, high energy conversion efficiency can be obtained by using resonance.

Electric power generating apparatus for movement type equipment and self-generation system having the same

Growth and characterization of silicon-nitride films by plasma-enhanced chemical vapor deposition

Lithiated layered transitional metal oxide materials of the LiMO2 type and especially LiCoO2 presents interesting specific properties as high energy density, long cycle life and constant discharging properties in a wide range of working conditions as well as a good safety. These properties made these materials excellent candidates as active compounds for high capacity cathode materials for rechargeable lithium batteries. LiCoO2 is the most common lithium storage material for lithium rechargeable batteries, used widely to power portable electronic devices. Operation of lithium rechargeable batteries is dependent on reversible lithium insertion and extraction processes into and from the host materials of lithium storage. In this study, LiCoO2 thin films were prepared by the sol–gel spin coating technique using metal acetate and citric acid as starting materials. Citric acid acts as a chelating agent, which promotes the preliminary reaction between lithium and cobalt and suppresses the precipitation of acetates. The sol–gel method is well known as one of promising thin-film preparation methods, which has good advantages such as low fabrication cost, relatively easy stoichiometry control, high deposition rate and also known as a low-temperature synthesis method for various ceramics. In addition, the crystal phases involved in the thin film can also be controlled by changing the chemical compositions of the sol. The crystallinity, microstructure and electrochemical properties of final films are also studied by XRD, SEM, AFM and galvanostatic charge/discharge cycling test. Films heat-treated under appropriate conditions exhibit high capacity and good crystallinity so those films are considered to be candidates as cathodes for thin-film micro batteries.

Yoon-Pyo Lee

Papers

Modeling and Characterization of Piezoelectric $d_{33}$ -Mode MEMS Energy Harvester

A Study on Ice Slurry Production by Water Spray

Electric power generating apparatus for movement type equipment and self-generation system having the same

Growth and characterization of silicon-nitride films by plasma-enhanced chemical vapor deposition

LiCoO2 thin film cathodes grown by sol–gel method