Customizable, Flexible Pressure, and Temperature Step Sensors with Human Skinlike Color.

Durability and multifunctionality are very important factors for human skinlike tactile sensors for measuring physical stimuli if they provide reasonable pressure measurement range and sensitivity. Here, we propose a step tactile sensor with a simple processing unit, showing high repeatability and mechanical stability without drifting caused by thermal and geometrical noise. The proposed sensor, similar to a switch mechanism, detects the applied pressure discretely and has a wide pressure range of 2 kPa to 1.2 MPa according to its geometry. The developed tactile sensor can be designed and fabricated in various morphologies to detect a wide range of tactile stimuli, which help in customizing the sensor as per user demand for practical applications such as a prosthesis arm or hand. It is also easy to extend the sensor size to cover a large area owing to the simple fabrication process by using a 3D printer. Furthermore, with the addition of a flexible exterior layer of leuco dyes and the polydimethylsiloxane mixture, the color of a step tactile sensor not only resembles that of human skin color but also changes its color depending on the temperature changes as human skin does. Thus, the function of a pressure and temperature indicator in a flexible step sensor finds practical applications in various fields, including but not limited to prosthetic applications for the customized and comfortable usage.