By Cameron Chai
Researchers led by Kenji Hata at the Advanced Industrialof Science and Technology at Tsukuba in Japan have developed a strain sensor that deploys a carbon nanotube network to repeatedly break up and put it back together in the same order.
The team cultivated thin layers of single-walled carbon nanotubes and set them on a sheet of silicon rubber. Care was taken to see that the tube lengths ran against the stretch direction. An isopropyl alcohol drop forced the air out between the film and the substrate causing a strong grip.
The initial tug on the dense cross-section of nanotubes causes cracks between them, changing the network into thick islands and filament bridges that cause the electron traffic to choke resisting the sensor's electrical conductivity. When the stretch is relaxed, the bridges and islands revert to their original like an accordion. The fabric does not develop cracks in other places. This makes the sensor durable. It also lasts longer than the silicon rubber.
The team has fixed the sensor to bandages, stockings and gloves to find out if it could track the movement of a human body. They discovered that it could detect large movements innumerable times.
It can be attached to the chest like a respiratory monitor to possibly help avoid sudden infant death syndrome (SIDS). Used as a ‘data glove’, it can detect the movement of individual fingers, and detect typing. The team says it could also guide robots during surgical procedures.