Big step toward solar power for small electronic devices

Engineers have debuted a circuit they say can power wearables, sensors and other electronic devices with a steady and renewable power source from solar energy that could fuel the growth of the "Internet of Things."

New ultralow-power circuit improves efficiency of energy harvesting to more than 80 percent.
Source: M.I.T.

Two MIT engineers who developed the chip say it does a far better job of converting the energy captured by solar cells into usable electricity than current technology does, and the invention lends itself well to creating self-powering electronic sensors that can be used in a wide range of applications. (Tweet This)

They introduced the device last week at the Symposia on VLSI Technology and Circuits in Kyoto, Japan.

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Sensors are a crucial ingredient to the "Internet of Things," the notion that devices, or even organisms, can be linked to networks, through which they can deliver important information, such as performance levels, maintenance issues or research. For example, scientists have proposed embedding sensors in human skin that can measure everything from blood pressure to vitamin levels. Sensors are also used commonly in electronic devices (even cars and planes), or even in research applications such as measuring air quality.

But such devices require a power source, and carrying around batteries or removing sensors to charge them is often not feasible. Devices need batteries that either last a very long time or possess the ability to recharge themselves. Renewable energy sources such as solar power could, in theory, provide that kind of power.

But solar power has an efficiency problem: Circuits today can convert only about half of the energy that solar cells collect into usable electricity. For that reason, solar energy isn't often practical for smaller devices that have little space to spare for solar cells, or devices that have to operate in low light environments.

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The small circuit developed by Dina Reda El-Damak and Anantha Chandrakasan at MIT is an ultralow-power circuit that converts roughly 80 percent of that energy directly into electricity. The new MIT circuit can both power devices and charge a battery connected to devices, another capability that has eluded such circuits so far.

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"There is fixed overhead in terms of converting solar energy to power electronics," Chandrakasan told CNBC. "So the innovation in this chip is all about how you make that energy conversion extremely efficient."

"This enables a new class of 'Internet of Things' devices, because this new generation will have to conserve a very small amount of power," Chandrakasan said.

El-Damak was funded by a Texas Instruments Fellowship for Women in Microelectronics, and the chip was fabricated by Taiwan Semiconductor Manufacturing.