Electrical engineers at the University of California, San Diego (UCSD), have unveiled a temperature sensor capable of running on just 113 picowatts of power: 628 times less power than the current state of the art and roughly 10 billion times smaller than a watt. Could this technology power the unobtrusive ‘unawearables’ of the future?
The technology could open the door to wearable devices with a battery life far beyond anything in production today. Systems that monitor body temperature, smart homes, Internet of Things (IoT) devices and environmental monitoring could all be transformed.
The first step towards ‘unawearables’
In a paper published in Nature, Near-Zero-Power Temperature Sensing via Tunnelling Channels Through Complementary Metal-Oxide-Semiconductor Transistors, UCSD researchers Hui Wang and Patrick P. Mercier explain how the technology could enable a new class of tiny wearable devices.
The ambition is to harness the technology to develop smaller wearables that can be powered by harvesting energy from ultra-low-power sources, including the body and the surrounding environment. This could spell the end of battery changes and the need to remove devices in order to charge them.
“Our vision is to make wearable devices that are so unobtrusive, so invisible that users are virtually unaware that they’re wearing their wearables, making them ‘unawearables’”, said senior study author Patrick Mercier.
“Our new near-zero-power technology could one day eliminate the need to ever change or recharge a battery.”
While removing the need for battery changes completely remains the ultimate ambition, extending current battery life from days and weeks to years is a genuine possibility. “We’re building systems that have such low power requirements that they could potentially run for years on just a tiny battery,” said Hui Wang, an electrical engineering PhD student in Mercier’s lab and the primary author of the study.
Near-Zero-Power temperature sensors
Moving away from wearables and ‘unawearables’, it’s arguably the environmental sector that stands to benefit most from ultra low-power temperature sensors. Remote devices out in the field, including buoys and other temperature-reading systems, could soon be powered for the long term. These would allow climate scientists to grow larger networks of sensors and have access to more data than ever before.
The temperature sensor developed at UC San Diego is tiny as well as highly efficient. Integrated into a chip measuring just 0.15mm squared, it can operate at temperatures between -20C and 40C.
The one trade-off in terms of performance is that the sensor has a slower response time than technologies currently in use. However, with one temperature update per second, the rate is adequate for measuring relatively stable entities. Environmental and body temperature readings don’t tend to fluctuate.
In the coming weeks and months, the UCSD team has plans to improve the accuracy of the temperature sensor. It will also start the process of optimizing the design to enable their technology to be used in commercial devices.
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