Researchers create temperature sensor that runs on almost no power

Researchers at UC San Diego have developed a temperature sensor that runs on tiny amounts of power — just 113 picowatts, around 10 billion times less power than a watt. The sensor was described in a study recently published in Scientific Reports . “We’re building systems that have such low power requirements that they could potentially run for years on just a tiny battery, ” Hui Wang, an author of the study, said in a statement . The team created the device by reducing power in two areas. The first was the current source. To do that, they made use of a phenomenon that many researchers in their field are actually trying to get rid of. Transistors often have a gate with which they can stop the flow of electrons in a circuit, but transistors keep getting tinier and tinier. The smaller they get , the thinner the gate material becomes and electrons start to leak through it — a problem called “gate leakage.” Here, the leaked electrons are what’s 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. The researchers also reduced power in the way the sensor converts temperature to a digital readout. The result is a temperature sensor that uses 628 times less power than the current state-of-the-art sensors. The near-zero-power sensor has a temperature range of -4 to 104 degrees fahrenheit and could potentially be used in wearables and both environmental and home monitoring systems. One power tradeoff is that it gives readouts slightly slower than currently used sensors, at around one temperature read per second. But the researchers said that shouldn’t be a problem when giving reads on things like the human body where temperatures don’t change too quickly. They’re now working on optimizing the design and improving its accuracy. [Image: UC San Diego Jacobs School of Engineering] Via: UCSD Source: Scientific Reports

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Researchers create temperature sensor that runs on almost no power

Scientists built a chip without semiconductors

Remember when you saw those old-timey photos of room-sized vacuum-tube-powered computers , and laughed and laughed? That tech might be making a comeback, thanks to work from scientists from UC San Diego . They’ve built the first semiconductor-free, laser-controlled microelectronics device using free electrons in air, much like how vacuum tubes work. The research could result in better solar panels and faster microelectronic devices that can carry more power. Semiconductors based on silicon and other materials are great, obviously, having helped us squeeze billions of transistors into a few square inches. But they have some issues: Electron velocity is limited by the resistance of semiconductor materials, and a boost of energy is required to just to get them flowing through the “band gap” caused by the insulating properties of semiconductors like silicon. Vacuum tubes don’t have those problems, since they use free electrons in the air to carry (or not) a current. Getting free electrons at nanoscale sizes is problematic, however — you need either high voltages (over 100 volts), high temperatures or a powerful laser to knock them loose. The UC San Diego team solved that problem by building gold “mushroom” nanostructures with adjacent parallel gold strips (above). By combining a relatively low amount of power (10 volts) with a low-powered laser, they were able to dislodge electrons from the gold metal. The result was a tenfold (1000 percent) increase in conductivity in the system, a change sufficient “to realize on and off states, that is, the structure performs as an optical switch, ” according to the paper in Nature . The device can thus act as a transistors, power amplifier or photodetector, much as semiconductors do. However, it can theoretically work with less resistance and handle higher amounts of power. So far, the research is just a proof-of-concept, but it’s very promising. “Next, we need to understand how far these devices can be scaled and the limits of their performance, ” says author Dan Sievenpiper. The team aims to explore applications not just in electronics, but photovoltaics, environmental applications and, possibly, weaponry — the research was funded, after all, by DARPA. Source: UC San Diego

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Scientists built a chip without semiconductors