Self-powered stretchable thermometer can be integrated into soft robot, smart

The next generation of soft robotics, smart clothing and biocompatible medical devices will require integrated soft sensors that can stretch and twist with the device or wearer. Challenge: Most of the components used in conventional sensing are rigid.

Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a soft, stretchable, self-powered thermometer that can be integrated into stretchable electronics and soft robots.

“We have developed soft temperature sensors with high sensitivity and quick response times, opening up new human-machine interfaces and new possibilities for building soft robots in healthcare, engineering and entertainment,” said Alan E. and Marilyn M. Puckett Professor Xigang Su said. of Mechanics and Materials at SEAS and senior author of the paper.

research is published in Proceedings of the National Academy of Science,

The thermometer consists of three simple parts: an electrolyte, an electrode, and a dielectric to separate the two. The electrolyte/dielectric interface deposits ions while the dielectric/electrode interface deposits electrons. The charge imbalance between the two sets up an ionic cloud in the electrolyte. When the temperature changes, the ionic cloud thickness changes and a voltage is generated. Voltage is sensitive to temperature, but insensitive to strain.

“Because the design is so simple, there are many different ways to customize the sensor depending on the application,” said Yicheng Wang, a postdoctoral fellow at SEAS and first author of the paper. “You can choose different materials, arranged in different ways and adapted to different tasks.”

By arranging the electrolyte, dielectric and electrode in different configurations, the researchers developed four designs for the temperature sensor. In one test, they integrated the sensor into a soft gripper and measured the temperature of a hot hard-boiled egg. The sensors are more sensitive than traditional thermoelectric thermometers and can respond to changes in temperature within about 10 milliseconds.

“We showed that these sensors can be made small, stable and even transparent,” Wang said.

Depending on the material used, the thermometer can measure temperatures above 200 °C or as cold as -100 °C.

“This highly customizable platform could usher in new developments to enable and improve the Internet of Everything and Everyone,” Sue said.

Research co-authors Kun Jia, Shuwen Zhang, Hyong Joon Kim, Yang Bai and Ryan C. Hayward was.