Fabrication of Textured Ni-Coated Carbon Tubes for a Flexible Strain Sensor: Effect of the Device Elastic Modulus on Sensor Performance

The exploration of flexible resistive sensors with excellentperformanceremains a challenge. In this paper, a nickel-coated carbon tube witha textured structure was prepared as a conductive sensitive materialand inserted into the poly(dimethylsiloxane) (PDMS) polymer; interestingly,the sensor performance was controlled by the elastic modulus of thematrix resin. The results show that Pd2+ may be adsorbedby the active groups on the surface of a plant fiber as a catalyticcenter for the reduction of Ni2+. After 300 & DEG;C annealing,the inner plant fiber would be carbonized and attached to the outsideof the nickel tube; to be precise, the textured Ni-encapsulated Ctube was fabricated successfully. It is worth noting that the C tubeserves as a layer of support for the external Ni coating, providingsufficient mechanical strength. In addition, resistance sensors withdifferent properties were prepared by controlling the elasticity modulusof the PDMS polymer by introducing different contents of curing agents.The limit uniaxial tensile strain was enhanced from 42 to 49% andsensitivity reduced from 0.2 to 2.0% with the elasticity modulus ofthe matrix resin increasing from 0.32 to 2.2 MPa. As expected, thesensor is obviously appropriate for the detection of elbow joints,human speaking, and human joints with the reduction of the elasticitymodulus of the matrix resin. To be precise, the optimal elastic modulusof the sensor matrix resin would facilitate the improvement of itssensitivity to monitor different human behaviors.