Energy-scavenging system

Energy-scavenging systems being developed by MIT Prof Anantha Chandrakasan and Dr Yogesh Ramadass could provide power for sensors through from differences in temperature between the body and the surrounding air.

The unique aspect of the MIT-developed devices is their ability to harness differences of just one or two degrees, while producing about 100 microwatts of useable power.

The key to the technology is a control circuit that performs optimal transfer of the extracted energy from a thermoelectric material to a storage capacitor, while regulating the output at 1.8V.

A system based on the device could enable 24-hour-a-day monitoring of heart rate, blood sugar or other biomedical data, through a simple device worn on an arm or a leg and powered by the body’s temperature, which, except on a 98.6F summer day, would almost always be different from the surrounding air.

It could also be used to monitor the warm exhaust gases in the flues of a chemical plant, or air quality in the ducts of a heating and ventilation system.

The present experimental versions of the system require a metal heat sink worn on an arm or leg, exposed to the ambient air.

’There’s work to be done on miniaturising the whole system,’ Ramadass said. This might be accomplished by combining and simplifying the electronics and by improving airflow over the heat sink.