Loreto Mateu

Review of energy harvesting techniques and applications for microelectronics

The trends in technology allow the decrease in both size and power consumption of complex digital systems. This decrease in size and power gives rise to new paradigms of computing and use of electronics, with many small devices working collaboratively or at least with strong communication capabilities. Examples of these new paradigms are wearable devices and wireless sensor networks. Currently, these devices are powered by batteries. However, batteries present several disadvantages: the need to either replace or recharge them periodically and their big size and weight compared to high technology electronics. One possibility to overcome these power limitations is to extract (harvest) energy from the environment to either recharge a battery, or even to directly power the electronic device. This paper presents several methods to design an energy harvesting device depending on the type of energy avaliable.

Optimum Piezoelectric Bending Beam Structures for Energy Harvesting using Shoe Inserts

The small amount of power demanded by many present-day electronic devices opens up the possibility to convert part of the energy present in the environment into electrical energy, using several methods. One such method is to use piezoelectric film-bending beams inside a shoe, and use part of the mechanical energy employed during normal walking activity. This study analyzes several bending beam structures suitable for the intended application (shoe inserts and walking-type excitation) and obtains the resulting strain for each type as a function of their geometrical parameters and material properties. As a result, the optimum configuration can be selected.

Human Body Energy Harvesting Thermogenerator for Sensing Applications

A low temperature thermal energy harvesting system to supply power to wireless sensing modules is introduced. The thermoelectric generator module (TEG) makes use of the temperature gradient between the human body (the heat source) and the ambient to deliver a low voltage output that is up-converted by means of a power management circuit. This regulated power source is able to reliably supply a wireless communication module that transmits the collected temperature, current and voltage measurements.

System-Level Simulation of a Self-Powered Sensor with Piezoelectric Energy Harvesting

This paper presents a complete system simulation of a self-powered communication module. The components are described with the Verilog-A language, that allows to merge the electrical and mechanical models of the system. The self-powered sensor system is composed by an energy harvesting piezoelectric generator that powers a RF transmitter. The simulations here presented compare between the case of a battery-less and battery-powered system. The results obtained with the simulation model implemented allow to show how design choices of the system change the periodicity of the transmission and the ability to recharge the battery.

Physics-Based Time-Domain Model of a Magnetic Induction Microgenerator

This paper presents a study of a time-domain model of a magnetic induction microgenerator for energy harvesting applications. The model is based on a simple structure for which an analytical expression of the magnetic field distribution can be computed. From this analytical expression, geometric parameters that are not taken into account in the previous literature on microgenerators are considered. Starting from the magnetic field distribution in space of a circular current loop, the paper derives the induced electromotive force in a coil depending on the distance to the magnet. Simulations give insight into the validity of linear models implicitly assumed in frequency-domain analysis of these systems

Analysis of Direct Discharge Circuit to Power Autonomous Wear-able Devices using PVDF Piezoelectric Films

Advances in low power design open the possibility to harvest energy from the environment to power electronic circuits. A piezoelectric element is capable of transform mechanical energy into electrical energy. Several methods are possible to efficiently store the generated electrical energy. Direct discharge method is here analyzed for a realistic piezoelectric current source waveform when the mechanical excitation is human walking activity. This analysis allows to predict how many steps are needed to provide a given amount of energy to an electronic device

Analytical Method for Selecting a Rectification Technique for a Piezoelectric Generator based on Admittance Measurement

AC-DC converters employed for harvesting power from piezoelectric transducers can be divided into linear (i.e. diode bridge) and non-linear (i.e. synchronized switch harvesting on inductor, SSHI). This paper presents an analytical technique based on the measurement of the impedance circle of the piezoelectric element to determine whether either diode bridge or SSHI converter harvests more of the available power at the piezoelectric element.

Modeling of Hybrid Piezoelectrodynamic Generators

Abstract Vibrational energy harvesters are used for collecting electrical power from mechanical vibrations and supplying low power applications. Combining a piezoelectric generator with an electrodynamic generator creates a hybrid piezoelectrodynamic generator. In this paper, a model for this hybrid generator is proposed. The model allows the accurate simulation of the mechanical and electrical part of the generator. It also makes it possible to analyze the waveforms and phase relationships of the two electrical outputs of the hybrid generator and thus simulate power management circuits and their feedback on the generator.