Made from a rubber infused with graphene nano-flakes, it has been tested with elongation up to 350% and over 10,000 cycles of stretching and relaxing while maintaining electrical stability.
“We tested this sensor vigorously,” said Professor Homayoun Najjaran. “Not only did it maintain its form but more importantly it retained its sensory functionality.
The goal was to make a reasonably sized robust sensor for human sensing that could stretch and flex yet be made at realistic cost.
“We have introduced an easy and highly repeatable fabrication method to create a highly sensitive sensor with outstanding mechanical and electrical properties at a very low cost,” claimed fellow researcher Professor Mina Hoorfar.
Three wearable devices were developed, using the sensor to measure knee movement, finger movement, and heartbeat through the radial artery – by attaching strips of the material to a knee band, a wrist band and a glove – indicating that the same material can sense over entirely different ranges of movement, according to the university.
“The gauge factor of the sensor ranges from 2 to up to 160, which allows the sensor to monitor a great variety of human motions,” said the team in the abstract of the paper ‘Low-cost ultra-stretchable strain sensors for monitoring human motion and bio-signals‘, published in the Journal of Sensors and Actuators A.
Stuck to the back of a glove across finger joints, multiples of the sensor have also been demonstrated controlling a robot hand.