A cellulose-based hydrogel continues sensing movement in extreme cold, offering a flexible approach to wearable electronics, robotics and human-machine interfaces.
Researchers have developed a 3D-printed cellulose hydrogel that allows wearable sensors to continue operating in extreme cold. The material remained functional at −13°F (−25°C) for 168 hours, continuing to produce electrical signals when exposed to movements such as finger bending and fingertip pressing. The source does not identify a commercial company or product associated with the research.
The researchers created the hydrogel by converting cellulose pulp into an electrically conductive material. They used a mixture of zinc chloride and lithium bromide salts to dissolve the cellulose while preserving the resulting molecular chains. The dissolved material was then formed into a transparent hydrogel.
The resulting material combines electrical conductivity with mechanical strength and resistance to freezing. Researchers measured ionic conductivity of 4.48 S/m and compressive stress of up to 2.48 MPa. Tests between −112°F and 68°F showed that water crystallisation was suppressed, helping the material maintain its properties in low temperatures.
Its ability to undergo shear thinning also makes the hydrogel suitable for 3D printing. It can flow under pressure and retain its shape after printing, allowing researchers to produce structures such as five-pointed stars and maple leaves.
For direct use on the body, the team added a polydopamine coating to improve skin compatibility. Sensors made from the hydrogel can be attached to fingers, wrists, elbows and the throat to detect movement and pressure.
The wearable sensor responded in about 100 milliseconds and recovered in roughly 300 milliseconds. It maintained stable performance through 500 compression cycles at 30 per cent strain.
The researchers demonstrated the technology in a data-glove system that detected hand movements and translated them into corresponding movements on a robotic model in real time. The work could therefore support wearable electronics, robotics and human-machine interfaces that require flexible sensors in cold environments.
