Crazy-efficient temperature sensor uses less than 1-billionth of a watt

Luke Dormehl
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Chances are that you do not talk about picowatts too much in your day-to-day life. No, it is not the name of a yellow Pokémon, but a measure of power that is equal to a trillionth of a watt. Given that a standard incandescent bulb uses in the region of 60 watts, you get a sense of just how tiny a picowatt actually is. Well, electrical engineers at the University of California, San Diego have managed to pull off the miraculous feat of developing a temperature sensor that runs on just 113 picowatts of power. To provide a bit more context, that is 628 times lower power than the previous state-of-the-art technology and 10 billion times smaller than a single watt.

“What we’ve built is a digital thermometer that operates with nearly zero power consumption,” Patrick Mercier, an electrical engineering professor at UC San Diego and the study’s senior author, told Digital Trends. “Normally, digital thermometers are used to monitor ambient air temperature, the temperature of the human body, or the temperature of seawater, industrial equipment, or a large number of other applications — requiring significant power to operate. This means such devices must employ larger than desired batteries, or be connected to wall power, which is inconvenient and increases the overall size of the device.”

So why build a near-zero power temperature sensor then? One word: Wearables. With a sensor that not only requires virtually no power to operate, but is also just a square millimeter in size, the number of possible uses opens up significantly. Its lack of power demands means that it could run for a very long time off a small battery — or even potentially operate using nothing more than scavenged energy found in the environment.

As to what is next for the project, Mercier said the team would like to further improve the accuracy of the sensor, while also expanding its temperature range to include more harsh environments. “Additionally, we are working to incorporate this sensor into various wearable and implantable systems to monitor the core temperature of the human body for fitness and medical applications,” he said.

A paper describing the work was recently published in the journal Scientific Reports.