The burgeoning field of soft robotics has been riding a surge of interest as of recent; the brightest of minds from the world over are now developing and improving ways of constructing robots that can execute specific tasks without the presence of rigid parts that most would otherwise ascribe them to.
Recent news from Harvard University suggests that they’re now jumping in, and they’re ready to make a splash; researchers from the institution’s John A. Paulson School of Engineering and Applied Sciences (SEAS) recently revealed a truly unique take on technology that’s otherwise one of the oldest we have, as they’ve made a stretchy and “soft” self-powered thermometer. Their new take on thermometers was summarized in a study that was published in the Proceedings of the National Academy of Sciences.
The thermometer itself is composed of distinct parts: an electrode, a hydrogel electrolyte with salts within its structure, and a non-conductive dielectric material. When the three are bunched up together, they manage to create two phenomena within the material that create the temperature-sensing function of the entire device.
You see, the interface between electrolyte and dielectric gathers up ions, while that between the dielectric and the electrode does the same for electrons. The difference in charge between the two accumulations creates a so-called “ionic cloud” within the electrolyte layer—and this is where the temperature sensing happens, as this cloud changes thickness and generates a voltage when it experiences a change in temperature. This voltage is measurable—and perhaps more importantly to its other unique property—is also insensitive to the amount of stretch the electrolyte experiences.
“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 senior author and SEAS Allen E. and Marilyn M. Puckett Professor of Mechanics and Materials Zhigang Suo in the institution’s press release.
First author and SEAS postdoctoral fellow Yecheng Wang followed: “Because the design is so simple, there are so many different ways to customize the sensor, depending on the application. You can choose different materials, arranged in different ways and optimized for different tasks.”
The team arranged the three components and managed to eke out four designs that enabled different functionalities; in fact, in one test, they managed to co-opt their soft technology into a gripper, which enabled them to measure the temperature of a hard-boiled egg—a feat which wouldn’t be so difficult for the novel thermometer, perhaps, given that it can measure temperatures between -100 and 200 °C with sensitivity to temperature changes in the range of milliseconds.
Finally, the authors noted that their new type of thermal sensor can be made “small, stable, and even transparent,” which could then enable the “highly-customizable platform” to “usher in new developments.”
References
- Burrows, L. (2022, January 20). A soft, stretchable thermometer. Harvard John A. Paulson School of Engineering; Harvard John A. Paulson School of Engineering. https://www.seas.harvard.edu/news/2022/01/soft-stretchable-thermometer
- Coxworth, B. (2022, January 26). Stretchable, flexible thermometer could find use in soft robotics. New Atlas. https://newatlas.com/robotics/soft-robotics-thermometer/
- Wang, Y., Jia, K., Zhang, S., Kim, H. J., Bai, Y., Hayward, R. C., & Suo, Z. (2022). Temperature sensing using junctions between mobile ions and mobile electrons. Proceedings of the National Academy of Sciences, 119(4). https://doi.org/10.1073/pnas.2117962119
