Soft sensors for wearables have to stand up to challenges that sensors in wristbands, pins, belt packs, and glasses never experience. We’ve written about enabling technology developments such as printed stretchable conductors, stretchable fabric battery design, a stretchable display that senses touch, and 3D printed stretchable tactile sensors for garment applications. Withstanding stretching is not the only challenge wearable sensors face. Threats to smart garment sensors include washing and blows from a variety of sources including being stepped on by clothes-hanger-challenged owners.
Engineers at Harvard’s John A. Paulson School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering recently published a paper in Nature about a new “seriously resilient” strain sensor. The research team’s sensor consists of conductive carbon fibers in a serpentine pattern between two elastic substrates. The sensor detects difference in conductivity when the fibers are closer or further away depending on strain (pulling) on the edges of the sensor.
The researchers stabbed the sensor with a scalpel, hit it with a hammer, ran it over with a car, and put it through the washing machine cycles. The sensor didn’t suffer damage from any of these torture tests.
The Paulson and Wyss team demonstrated potential applications for the sensor by embedding it in a fabric arm sleeve. Based on small changes in the subject’s forearm muscle, a machine learning algorithm learned to accurately differentiate between hand gestures such as a fist, pen palm, and pinching.
The sensor’s combined sensitivity and robustness suggest applications ranging from virtual reality simulations and smart sportswear to diagnostics for Parksinson’s Disease and other neurodegenerative disease. Next steps for the engineers include exploring ways the sensor can be integrated into clothing.
