There is a growing need for stretchable electronics and sensors, and so we have developed a best-in-class stretchable strain gauge designed to meet this challenge. Our device works by measuring capacitive changes in parallel networks of carbon nanotubes separated by an elastomer. The device supports strains up to 100% with less than 3% variability over 3000 cycles, and does so at a materials cost of under 50 cents/sensor. The sensitivity is 0.99, while the theoretical maximum for a stretchable gauge is 1. By contrast, metal-foil gauges (the current standard) can only sustain strains of 5% before failure. Given these specifications, our sensor is uniquely poised to contribute to robotics, medical implants, and high-tech clothing. As an example of these applications, we have tested our sensor as an integrated component in a new class of ultra-light, foldable, legged robots inspired by insect locomotion. By incorporating it into a position where it both acts as an energy storage device and a displacement sensor, we can accurately transduce parameters such as joint angles and relative foot displacement. To date, these measurements have not been possible due to the limitations of metal-foil gauges and the high weight of alternate sensors.
Project end date: 08/16/12