Power Harvesting

Joe Paradiso

Power Harvesting
We have developed a compact, wireless, barreryless pushbutton controller that transmits a 12-bit digital ID code to the vicinity when it is pressed. The device produces on the order of a milliJoule at 3 Volts when pushed, enabling several cycles of the ID code to be transmitted over scores of meters. Previous approaches used piezoceramic actuators to send simple impulses across Hertzian Resonators, such as this toy pager that used to be marketed by Tomy. Our device uses a reactively-matched transformer to drop the impedance of the piezo source, enabling one push to easily power low-voltage circuitry that can produce and transmit the code. This device has myriad applications, e.g., in places where a control interface is desired, but where physical wiring is impractical or too expensive, or where an embedded battery is undesireable because of limited shelf life or environmental concerns. This work evolved out of our prior project on power harvesting in shoes.

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