Energy Harvesters are materials and devices that allow ambient energy sources to be converted into usable electrical power. There are several forms of ambient energy sources which generate power that can be captured and stored for use in powering wireless sensor networks.
Electrodynamic generators and piezoelectric materials enable vibration to be converted to electrical energy. Electrodynamic generators are coils and magnets in motion, producing an alternating current that is converted to power. Piezoelectric materials are applied to vibrating structures and the resulting stress or strain on the material will result in an output of alternating current which is converted to power. The MicroStrain EH-Link is able to be powered by both electrodynamic generators and piezoelectric materials.
Photovoltaic cells are a convenient source of generating electrical energy, both indoors and outside. However, operating indoor solar cells causes the power output to drop exponentially due to lower light levels. EH-Link power consumption is low enough that it can operate indoors with a very small array of solar cells.
A solar cell array for generating electrical energy is included in the MicroStrain EH-Link Pioneer Kit.
Harvesting energy from strain can be accomplished with piezoelectric materials. The piezoelectric material can be mounted to a structure that is under strain, and the material, which is also then stressed or strained, will output an alternating current proportional to the strain on the structure. MicroStrain's EH-Link can be efficiently powered from the resulting AC using piezoelectric materials.
Piezoelectric harvester manufacturers include Smart Material, Inc.
Energy generation can occur when a temperature gradient between a thermoelectric device and ambient air temperature exists. Such thermoelectric devices output a very low voltage for a low source resistance. The MicroStrain EH-Link is able to utilize this low voltage to power wireless sensors solely from power converter from heat to electricity.
A thermal harvester is included in the MicroStrain EH-Link Pioneer Kit.
Thermal harvester manufacturers include Marlow Industries.