A POLYMER-BASED MEMS MULTI-MODAL SENSORY SKIN

. To date, robots do not have the sensing capability to provide them with an equivalent sense of “touch”. Devices that incorporate brittle sensing elements such as silicon-based diaphragms or piezoresistors, even embedded in protective polymers, cannot be used as the interface “skin” between a robotic manipulator and the manipulated object. Devices made with pressure sensitive rubbers that can withstand contact have been presented, but require serial manual assembly, are based on rigid substrates or provide limited independent sensing modes 2 . In an effort to overcome these limitations, we present a tough, monolithic polymer-based sensing skin that incorporates a number of metal film sensors. Multi-Modal Sensing Skin. The reported device is fabricated on DuPont Kapton HN200 2-mil-thick polyimide film. The use of a polymer substrate allows flexibility, robustness, and low material cost, with the ability to build additional polymer structures on the film. Our device is comprised of four distinct sensors, a reference nickel RTD for temperature measurement and compensation, a gold heater and nickel RTD pair for thermal conductivity measurement, a membrane NiCr strain-gauge based contact force and hardness sensor, and a reference contact hardness sensor (Fig 1a). In addition, the contour of the skin is sensed (although not presented here) in an integrated fashion using NiCr strain gauges dispersed between sensory nodes (Fig 1b). When the skin is mounted on a curved or compliant surface (e.g., a robotic finger tip), the spatial relation of sensor nodes is mapped to coordinate manipulation in 3D space. To the best of our knowledge, the development, integration, and characterization of thermal conductivity, hardness, and curvature sensors using polymer micromachining has not been previously achieved.