Effect of Nanoscale Surface Texture on the Contact-pressure-dependent Conduction Characteristics of a Carbon-nanotube Thin-film Tactile Pressure Sensor

Abstract

We report on a novel tactile pressure sensor structure that transfers the vertical pressure applied to the sample's surface to lateral strain in the carbon-nanotube thin film embedded in an elastomer by using a "wavy" structured substrate contact surface. When pressure was applied to the poly(dimethylsiloxane) (PDMS) surface, it was transferred to a carbon-nanotube thin film (CNTF) underneath, where it stretched to conform to the wavy substrate surface. This resulted in an elongation, or lateral strain, in the CNTF layer, their reducing its conductance. The measurements showed that with an applied vertical pressure of 30 kPa, a 15% reduction in conductance was achieved with only a 500-nm deflection in the CNTF, and repeatedly applied pressures for 3,600 cycles (12 hours) resulted in only a 2% reduction in sensitivity, demonstrating the their film's high sensitivity and reliability. The mechanical stability and high sensitivity of the CNTF/PDMS hybrid with wavy substrate structures may make possible applications to future tactile pressure sensors.