Sensors and sensitivity: Carbon nanotube buckypaper films as strain sensing devices

In this study we explore the effect of applied strain on the electrical resistance of carbon nanotube buckypaper films encapsulated in several types of epoxy resins. We find that such buckypaper sensors are indeed able to measure strains in polymers with different elastic properties and that the electrical resistance change similarly for all polymers tested here. For highly ductile polymers, the resistance change of the buckypaper sensors can be measured for strains higher than 30%, thus demonstrating surprisingly high sensitivity at large deformations. Different electromechanical responses are observed when the buckypapers are made of single-walled or multi-walled carbon nanotubes. The response of the buckypapers to the stress and strain distributions locally induced by well defined defects deliberately introduced into the resins is also assessed. The buckypaper sensors are found to be sensitive to the geometry of local defects.