SENSORS IN REMOTE LOCATIONS REQUIRE BATTERY FREE OPERATION

Energy Harvesting and Powering

Up the Battery-Free World

Oct 31, 2010 23:58 ideyoshi Kume

The idea behind wireless sensor networks is old, but a battery-free design would vastly expand its range of application. Voltree Power LLC of the US, a spin-off from the Massachusetts Institute of Technology (MIT) of the US, has been contracted by the US Department of Agriculture to construct a temperature sensor network in mountainous, forested regions of California Note 6).

Note 6) The power source is based on technology developed by MIT utilizing the electric potential difference between the tree trunk and surrounding area, which is between 50mV and 200mV.

The objective is to detect forest fires and minimize damage. Considering the damage cause by such fires, and the cost of firefighting personnel, equipment and supplies, the economics of constructing and operating a wireless sensor network are clear indeed.

One application attracting considerable attention of late is health monitoring. Sensors are mounted on buildings and bridges, detecting structural change. The amount and speed of these changes are used to diagnose the health of the structure, with acquired data utilized in guiding maintenance and component replacement.

There is considerable demand for health monitoring in the motor and engine sectors, as well. Automobiles use a large number of sensors to detect the conditions of various components, and as a result use vast quantities of wire harnesses. If engine and motor heat and vibration energy can be used to drive wireless sensors, it would be possible to dramatically cut the number of wire harnesses needed.

Another application in the health monitoring field is the life recorder, managing people and animals. Mounted on livestock or wild animals, for example, it can provide not only position information, but also data such as body temperature and pulse. If they can be powered by animal body heat, then there is no need for battery replacement.

Simple Enough for Everyone

Energy harvesting technology is the key behind the popularity of wireless sensor network, and with continuing development and wider recognition, a host of new applications will no doubt be pioneered. One major change in the environment is that companies getting into the energy harvesting field can now pick up low-power peripheral components very easily.

A large number of generating devices are already available from companies like AdaptivEnergy LLC of the US and Perpetuum Ltd. of the UK. For wireless technology, modules on the market eliminate the need for specialized knowledge of high-frequency waves. Alps Electric Co., Ltd. of Japan, which is volume producing a sensor network module using GainSpan’s wireless transceiver IC, has received inquiries from over thirty firms already.

Japan “A Decade Behind”

While the technology seems to be taking off, there are some worries for Japan: Japanese industry is almost invisible in the field energy harvesting field. Some people in the field warn that Japan is a decade behind Europe and America.

Sourced & published by Henry Sapiecha

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