Touch, or tactile sensing, is fundamentally important for a range of real-life applications, from robotics to surgical medicine to sports science. Tactile sensors are modeled on the biological sense of touch and can help researchers understand human perception and motion. A new approach to pressure distribution measurement uses tactile imaging technology.

The most common current approach to tactile imaging involves use of an array of sensors composed of pressure-sensitive materials; however, such arrays require complex fabrication processes and place limitations on the sensor design. The pressure between two conductors is directly related to the electrical contact resistance between them. Using this relationship, a sensor was developed that is composed of a pair of electromechanically coupled conductors, where one conductor has a driving function and the other performs the probe function. The sensor has no need for pressure-sensitive materials and is simpler to manufacture.

This strategy enabled development of a universal tactile sensor for contact pressure distribution measurement using simple conductive materials such as carbon paint. The design concept combines innovation in mechatronics technology — which enabled development of a flexible sensor based on conventional conductors connected to electrodes — with a tomography-based approach to determining the pressure distribution across the coupled conductors.

The proposed method improved on previous electrical impedance tomography-based tactile sensing techniques to provide sensors with high positional accuracy, adjustable sensitivity and range, and a relatively simple fabrication process. The sensors can be realized using various conducting materials including conductive fabrics and paints. Sheet-type flexible sensors were fabricated, along with finger-shaped sensors produced by coating 3D-printed structures with conductive paint.

The ease of adjustment of the sensitivity and sensing range and the pressure estimation precision means that this tactile imaging approach is expected to enable advanced control of multipurpose robots. The sensors could be used in fields such as remote device operation and industrial automation.

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This article first appeared in the September, 2021 issue of Tech Briefs Magazine.

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