Scientists at University of California San Diego have developed a “near-zero-power” temperature sensor that can create a path for a new class of devices, which will be powered by harvesting energy from low power sources. This temperature sensor runs on a tiny amount of power – only 113 picowatts, around 628 times less power than the state of the art.
“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, the first author of the study and an electrical engineering Ph.D. student in Mercier’s lab.
To create the device, the researchers minimized power in two areas. First, they reduced the current source by using a fact that many scientists in their field are trying to avoid. Transistors are able to stop the flow of electrons in a circuit using the gate they have, but keep getting smaller and smaller. The tinier the transistors get, the thinner their gate material becomes, which makes the electrons leak through it. The problem is known as “gate leakage.” Interestingly, these leaked electrons are the ones powering the sensor.
“Many researchers are trying to get rid of leakage current, but we are exploiting it to build an ultra-low power current source,” said Hui.
In addition, the researchers reduced power to make the sensor turn temperature into a digital readout. The result? A temperature sensor that runs on around 10 billion times less power than a watt.
This “near-zero-power” sensor operates at a temperature ranging from -4 to 104 degrees Fahrenheit. It can be used to expand the battery life of wearable and implantable devices, which monitor body temperature. Besides, this sensor has a potential use for IoT devices, smart home monitoring devices, and environmental monitoring systems. The study was published in Scientific Reports.