Pressure/Temperature Sensing Bimodal Electronic Skin with Stimulus Discriminability and Linear Sensitivity

TLDR

Human skin poorly discriminates pressure and temperature under mixed stimuli and shows nonlinear sensitivity, while electronic skin advances have yet to overcome these limitations. The study reports the first bimodal electronic skin that simultaneously detects and discriminates pressure and temperature stimuli in real time with linear sensitivity. By combining a novel device design with a temperature‑independent material, a surface‑wrinkled microstructure, and optimally reduced graphene oxide, the sensor achieves near‑perfect stimulus discriminability and linear response across a wide intensity range. The sensor delivers a linear pressure sensitivity of 0.7 kPa⁻¹ up to 25 kPa with a 50 ms response, a linear temperature coefficient of resistance of 0.83 % K⁻¹ between 22–70 °C with a 100 ms response, and can simultaneously detect and discriminate both stimuli using only impedance measurements.

Abstract

Abstract Human skin imperfectly discriminates between pressure and temperature stimuli under mixed stimulation, and exhibits nonlinear sensitivity to each stimulus. Despite great advances in the field of electronic skin (E‐skin), the limitations of human skin have not previously been overcome. For the first time, the development of a stimulus‐discriminating and linearly sensitive bimodal E‐skin that can simultaneously detect and discriminate pressure and temperature stimuli in real time is reported. By introducing a novel device design and using a temperature‐independent material, near‐perfect stimulus discriminability is realized. In addition, the hierarchical contact behavior of the surface‐wrinkled microstructure and the optimally reduced graphene oxide in the E‐skin contribute to linear sensitivity to applied pressure/temperature stimuli over wide intensity range. The E‐skin exhibits a linear and high pressure sensitivity of 0.7 kPa −1 up to 25 kPa. Its operation is also robust and exhibits fast response to pressure stimulus within 50 ms. In the case of temperature stimulus, the E‐skin shows a linear and reproducible temperature coefficient of resistance of 0.83% K −1 in the temperature range 22–70 °C and fast response to temperature change within 100 ms. In addition, two types of stimuli are simultaneously detected and discriminated in real time by only impedance measurements.