Carbon nanotubes-Polymer based Flexible Piezoresistive Strain Sensor for Wearable Device Applications

S. Vetrivel, K. Balasubramanian, R. Sundara
Indian Institute of Tehcnology Madras,

Keywords: carbon nanotubes, composites


Piezoresistive strain sensor is widely used in different applications such as structural health monitoring, wearable devices, robotics, and bio-functional prosthetic system. In all these applications, different kinds of real time linear and angular motions are involved. Functioning of strain sensor in all these conditions demands high flexibility along with robustness. In addition, a few under-water applications demand water resistance property. Conventional and commercially available metallic strain gauge has very less gauge factor and low measurement range due to its inelastic property. To design a waterproof flexible strain sensor, fabrication of polymer nanocomposite is one of the ideal solutions. Among various polymers, Polyvinylidene fluoride is inherent hydrophobic and piezomaterial. Researchers are exploring various novel high piezoresistive nanofillers such as carbon nanotubes (CNTs), graphene and silicon nanowires. The exceptional electrical, thermal and mechanical properties of CNTs, enable one to use it as nanofillers in the polymer matrix to enhance the electromechanical properties of the polymer nanocomposites. Polymer functionalized CNT-polymer based flexible waterproof strain sensor shows the gauge factor of ~10 which is 5-fold higher than the commercially available metallic strain gauge with excellent water resistant property. The waterproof flexible strain sensor developed is demonstrated to control the wireless enabled robotic arm for wearable device applications.