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)

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.

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Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices

DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

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Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

Piezoelectric transduction has received great attention for vibration-to-electric energy conversion over the last five years. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure, to generate electrical energy from base excitations. Several authors have investigated modeling of cantilevered piezoelectric energy harvesters under base excitation. The existing mathematical modeling approaches range from elementary single-degree-of-freedom models to approximate distributed parameter solutions in the sense of Rayleigh–Ritz discretization as well as analytical solution attempts with certain simplifications. Recently, the authors have presented the closed-form analytical solution for a unimorph cantilever under base excitation based on the Euler–Bernoulli beam assumptions. In this paper, the analytical solution is applied to bimorph cantilever configurations with series and parallel connections of piezoceramic layers. The base excitation is assumed to be translation in the transverse direction with a superimposed small rotation. The closed-form steady state response expressions are obtained for harmonic excitations at arbitrary frequencies, which are then reduced to simple but accurate single-mode expressions for modal excitations. The electromechanical frequency response functions (FRFs) that relate the voltage output and vibration response to translational and rotational base accelerations are identified from the multi-mode and single-mode solutions. Experimental validation of the single-mode coupled voltage output and vibration response expressions is presented for a bimorph cantilever with a tip mass. It is observed that the closed-form single-mode FRFs obtained from the analytical solution can successfully predict the coupled system dynamics for a wide range of electrical load resistance. The performance of the bimorph device is analyzed extensively for the short circuit and open circuit resonance frequency excitations and the accuracy of the model is shown in all cases.

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An experimentally validated bimorph cantilever model for piezoelectric energy harvesting from base excitations

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.

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

The device has a two terminal passive circuits (2) whose two input and output electrodes are connected to respective terminal electrodes of a piezoelectric insert (1) and a switching network. The network has switches connected with a passive dipole. One of the switches and remaining switches are closed when a potential difference between the terminal electrodes of the insert attains a maximum and minimum, respectively.

Shock absorbing device e.g. for aircraft cockpit, has two-terminal passive circuit whose two input and output electrodes are connected to respective terminal electrodes of piezoelectric insert and switching network

This paper presents electrical characterization and power management circuit of textile-based enzymatic biofuel cell. Firstly, static electrical characteristics (open circuit voltage, short circuit current, and maximum power) of the enzymatic biofuel cell have been investigated by imposing a voltage across the biofuel cell and measuring corresponding output current. Output power of the biofuel cell has been characterized as a function of load resistance, while a glucose solution of 100 mM is fed from one end of the textile-based biofuel cell. Two-step approach based on supercapacitor and DC-DC converter has been proposed and tested as power management of the proposed biofuel cell.

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Electrical Characterization of Textile-Based Enzymatic Biofuel Cell for Energy Harvesting Interface Circuit

We present the fabrication process and characterization of a novel Silicon-on-Glass electrostatic MEMS vibration energy harvester. This device is aimed to give supplementary energy to the battery of leadless pacemakers by using the vibrations generated by heartbeat movement. The proposed device is compliant with Leadless Pacemakers requirements: its dimensions are compatible with the 6mm- diameter capsules of leadless pacemakers for catheterism, and the materials composing the device are not ferromagnetic, allowing MRI imaging of implanted patients.

Microfabrication and Characterisation of an Electrostatic MEMS Energy Harvester for Biomedical Applications

This paper presents modeling and simulation of a cantilever-type piezoelectric energy harvester based on a combined FEM (Finite Element Method) and spice circuit. The PEH having dimension of 61 mm × 37 mm × 0.4 mm provides the maximum output power of 8 mW at resonant frequency of 127 Hz. The fabricated cantilever-type PEH (Piezoelectric Energy Harvester) has been characterized with variable resistor, which reveals that maximum power transfer is achieved at 10 kΩ. The modeling and simulation have beenperformed to study the effect of piezoelectric layer thickness on PEH output power in case of load resistance. FEM modeling and simulations have been carried out to extract electrical elements such as Rm, Lm, Cm, Cp and Γ. Those electrical elements have been included into a spice model to find optimal load resistance for maximum power transfer as well as. frequency response as function of piezoelectric layer thickness. Experiment and simulation show a good agreement on optimal load resistance. 

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Experiment and analysis of a piezoelectric energy harvester based on combined FEM modeling and spice simulation

We report the fabrication and characterization of two kinds of titanium membranes made of bulk titanium. Both membrane designs are compared mechanically to define the most suited for the targeted application. These membranes are future parts of Ti-based MEMS pressure sensors for active biomedical implants. As pressure is known to be linked to patient’s health for numerous diseases (glaucoma, heart failure, hydrocephalus...), in vivo pressure monitoring appears as a promising way to help medical doctors to define their treatments. Yet, most of current methods used to monitor pressure are still routinely invasive, which increases the risk of infection. The use of Ti as a mechanical transducer appears as a promising approach to tackle the lack of biocompatibility of standard semiconductor materials such as silicon, which requires a complex, bulky and costly packaging.

Elie Lefeuvre

Papers

Shock absorbing device e.g. for aircraft cockpit, has two-terminal passive circuit whose two input and output electrodes are connected to respective terminal electrodes of piezoelectric insert and switching network

Electrical Characterization of Textile-Based Enzymatic Biofuel Cell for Energy Harvesting Interface Circuit

Microfabrication and Characterisation of an Electrostatic MEMS Energy Harvester for Biomedical Applications

Experiment and analysis of a piezoelectric energy harvester based on combined FEM modeling and spice simulation

Mechanical comparison between two titanium micro membranes for in vivo pressure monitoring