Highly-efficient thermoelectric power harvesting

The project involves collaborative, multidisciplinary work combining materials research, device design and testing to develop a microgenerator/nanogenerator based on thermal power harvesting that can be used in applications such as wireless sensor systems, portable sensors, health care and industrial applications (such as embedded sensors in buildings and bridges). Wireless operation enables such microsystems to be completely embedded in a structure with no physical connection to the outside. Typically, the energy necessary to power such wireless systems is stored in batteries which have the following drawbacks: they tend to be bulky, contain a finite amount of energy and have a limited shelf life. The replacement of batteries places an additional cost, maintenance and environmental burden on the use of wireless sensor systems and is not suitable for embedded applications where battery replacement is not possible. The powering of wireless devices by harvesting energy from ambient sources present in the environment presents an opportunity to replace or augment batteries. The most common sources of ambient energy are: solar, vibration and thermoelectric.Thermoelectric power generation can be used in applications where a thermal gradient exists and the approach has many advantages over competing techniques. These include solid-state operation with no moving parts, long life-times (around 200, 000 hours i.e. over 20 years), no emission of toxic gases, maintenance free operation, and high reliability.The drawback of existing thermoelectric generators is their relatively poor efficiency. Commercially available devices are also quite bulky in size. The state-of -the-art of existing laboratory-developed prototype thermoelectric microgenerators delivers powers of about 1uW, which is just enough to power devices such as wristwatches, but this is not sufficient for modern day wireless sensor applications.This proposal will address these drawbacks by using state-of-the-art micromachining/nanotechnology techniques and is aimed at developing a new generation of micro/nano thermoelectric generator for power harvesting applications to improve the efficiency and harvesting potential of these devices to useful levels.