Recent advancements in soft robots, human-machine interfaces, and wearable electronics have led to an increased demand for high-performance soft tactile sensors. Tomographic tactile sensor based on resistive coupling is a novel contact pressure imaging method that allows the use of an arbitrary conductive material in a detector. However, the influence of material properties on the sensing performance remains unclear and the efficient and appropriate selection of materials is difficult. In this study, the relationship between the conductivity distribution of the material used as a detector and the sensing performance including sensitivity, force range, spatial resolution, and position accuracy is clarified to develop a high-performance tomographic tactile sensor. The performance maps reveal that a material with a conductivity of approximately 0.2 S/m can serve as an effective detector for touch interactions involving a force range of several Newtons. Additionally, incorporating gradient conductivity in the cross-section of the detector and multi-layer conductive porous media with anisotropic conductive bonding can help expand the design flexibility for enhanced performance. Based on these findings, various tomographic tactile sensors for soft grippers, tangible input interfaces, flexible touch displays, and wearable electronics are demonstrated by using a conductive porous media.
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