Fabrication of PDMS based flexible capacitive tactile sensor array with inkjet printed silver electrodes for robotic object grasp control

Abstract

Human interactive robots deployed for advanced services such as nursing and elderly assistance systems, operate in close proximity to humans in a home environment, unlike the conventional industrial robots. For the adaptive and safe interaction with humans, it is important to endow the sense of touch to such robots. Tactile sensors are embedded on the robotic body to perceive touch. The existing rigid tactile sensors have limited flexibility and conformability to robot surfaces. This paper presents the development of tactile sensors for robots to detect human touch, biomimicking the flexible nature of human skin. To emulate flexibility, we propose the fabrication of flexible capacitive tactile sensors based on polymers like Polyimide (PI) and Polydimethylsiloxane (PDMS). PI is used as the substrate to develop 3 × 3 array by thermal evaporation. PDMS is used as the dielectric between silver electrodes printed on Polyethylene terephthalate (PET) substrate adopting the state of the art and cost-effective inkjet printing. The sensitivity evaluation of the fabricated sensor was carried out using a customized force measurement setup. The pressure sensitivity of 0.32% /KPa was obtained. Force sensitive resistor (FSR) was integrated with the tactile sensor array to estimate force at contact location and was placed on the custom 3D printed robotic arm, for object grasp control. This novel tactile sensor module (TSM) can potentially offer improved user experience in human-robot interaction (HRI) as in Robotic elderly assistance systems.