One of the most exquisite heat sensors in the world - it’s not in some government lab. It's in the head of a snake. The pit viper, to be specific. "They're incredibly sensitive. They beat any of the,I would say, synthetic counterparts, even the most expensive semiconducting systems used for example in infrared or thermal cameras today." Chiara Daraio, a materials scientist at Caltech. "They can effectively resolve few millikelvin of temperature changes at a distance of up to a meter." Now Daraio and her colleagues have designed a heat-sensing material that competes with the sensitivity of the snake. Using pectin. Same stuff you used to thicken jam. “Pectin, which is a double-stranded molecule thats ubiquitously present on the outer cell wall of plant cells, acts effectively as a tiny molecular temperature sensor." When temperatures go up, she says, the double-stranded molecule unzips, "like the zipper of a jacket." So they did what you usually do with pectin - they made jelly, using pectin and water and calcium ions. They dried that out, and got a thin, transparent film. Then, they had to test it. Which they realized they could do using a microwave and her son’s teddy bear. "Which can be heated up to a temperature of 37 degrees, roughly the temperature for example of a mouse or a running prey for a snake." Pectin film was exquisitely sensitive to the warmed-up teddy bear - on par with the snake. The film could detect temperature changes as small as 10- thousandths of a degree celsius. The study is in the journal Science Robotics.