Temperature-insensitive and wide-range linear tactile electronic skins for reliable shape and texture recognition

Abstract

Electronic skins, emulating the tactile functionality of the human skin, are crucial for robotic applications. The sensitivity and pressure-sensing range of current humanoid tactile sensors have performed significant advancements. However, the temperature susceptibility of conductive materials and the rapid saturation of conductive contact sites in soft polymeric materials bring about challenges for these sensors, including environmental interference and a narrow linear sensing range. These issues lead to the inconsistencies between the sensing signal and contact behavior, which eventually deteriorates both the accuracy and reliability. Here, we propose a flexible piezoresistive pressure sensor with minimized response to temperature variation but extended linear sensing range. The sensor utilizes a novel hybrid conductive material elaborated to exhibit zero temperature resistance coefficient by combining the materials with the opposite temperature coefficients, which allows for a reliable operation ranging from 20 to 70 ℃ with temperature variation induced fluctuation free. Additionally, the sensor provides a biomimetic polymer microstructure with multilevel cone-dome structural feature, which results in an ultra-wide linear pressure-sensing range from 0 up to 200 kPa. In addition, based on the simple and scalable fabrication process, a high-density sensor array (16×16) is produced to outline the spatial pressure distributions accurately even under the external temperature interferences and successfully discern the texture of the contact object.