Lots of progress has been made (and continues) regarding soft sensors embedded in robotics and smart clothing, which are flexible and stretchable to a great extent.
Applying this concept to medical devices are researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) who 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 time, opening new possibilities to create new human-machine interfaces and soft robots in healthcare, engineering and entertainment,” said Zhigang Suo, Professor of Mechanics and Materials at SEAS.
Consisting of an electrolyte, an electrode and a dielectric material separating the two, the thermometer has a simple design. The electrolyte-dielectric interface accumulates ions, while the dielectric-electrode interface does the same for electrons. The charge imbalance occurring between them creates an ionic cloud in the electrolyte, whose thickness changes with a temperature change, resulting in voltage generation.
Multiple tests suggested that the sensors are more sensitive than traditional thermoelectric thermometers and can respond to temperature changes within about 10 milliseconds. The thermometer has a measuring range of -100 degrees Celsius to 200 degrees Celsius.
“Because the design is so simple, there are so many different ways to customise the sensor, depending on the application,” said Yecheng Wang, a postdoctoral fellow at SEAS. “You can choose different materials, arranged in different ways and optimised for different tasks.”
He adds that the sensors can be made small, stable and even transparent.
“This highly customisable platform could usher in new developments to enable and improve the internet of everything and everyone,” said Zhigang Suo.