MEMS and Sensors

Video: Stretchable, self-powered soft thermometer

26 January 2022

Researchers at the Harvard John. A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a soft, stretchable, self-powered thermometer sensor that could be the future of robotics, e-textiles and healthcare wearables.

The thermometer consists of three parts: an electrolyte, an electrode and a dielectric material to separate the two. The electrolyte/dielectric interface accumulates ions while the dielectric/electrode interface accumulates electrons. The charge imbalance between the two sets up an ionic cloud in the electrolyte. When temperature changes, the ionic cloud changes thickness, and a voltage is generated. The voltage is sensitive to temperature but not insensitive to stretching.

“We have developed soft temperature sensors with high sensitivity and quick response time, opening new possibilities to create new human-machine interfaces and soft robots in healthcare, engineering and entertainment,” said Zhigang Suo, the Allen E. and Marilyn M. Puckett Professor of Mechanics and Materials at SEAS.

Four designs

Researchers developed four designs for the temperature sensor by arranging the electrolyte, dielectric and electrode in different configurations.

They then tested the sensor. In one test, the integrated sensor was integrated into a soft gripper and measured the temperature of a hot hard-boiled egg. The sensors was more sensitive than traditional thermoelectric thermometers and responded to changes in temperature in about 10 milliseconds.

The thermometer can measure temperatures up to 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,” Suo said.

The full research can be found in the journal Proceedings of the National Academy of Sciences.

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