Design and Application of Flexible Resistive Tactile Sensor Based on Short-Circuit Effect

Abstract

Resistive tactile sensor has excellent anti-interference characteristics in daily environment. Inspired by the short-circuit effect in electricity, a new design of flexible resistive tactile sensor was proposed in this study. We utilized conductive graphite paint and conductive silver paint as sensing materials to fabricate the high-impedance element (100–150 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$ </tex-math></inline-formula> ) on the polyimide (PI) film and the low-impedance element (2– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\Omega$ </tex-math></inline-formula> ) on the silicone rubber, respectively. The output signal depends on the contact area between the high-impedance and the low-impedance elements caused by the applied pressure, which employs the short-circuit effect for the transduction mechanism. Besides, the spherical microstructure in silicone rubber layer was used to enlarge the measuring range of pressure. The experimental results show a wide range of pressure response up to above 3 MPa, and the resolution of the sensor with spherical structure is 79.6 kPa (0.25 N). The force sensing sensitivity of the sensor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S = - 5.733\times 10^{-4}$ </tex-math></inline-formula> kPa <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1}$ </tex-math></inline-formula> (from 0 to 799.4 kPa) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S = - 1.744\times 10^{-4}$ </tex-math></inline-formula> kPa <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1}$ </tex-math></inline-formula> (from 799.4 to 2834.4 kPa). Furthermore, an air gap between the high-impedance and the low-impedance elements was designed for restraining the interference of adjacent sensor arrays. Finally, we demonstrated the application in teleoperation and letter recognition, which implies that the proposed sensor has a great application potential in the field of robotics.