Flexible Thermal Perception Electronic Skin for Matter, Temperature, and Wind Detection

This research presents an innovative multifunctional electronic skin (e-skin) that utilizes a
$3\times3$
array of thermal sensing units, which are engineered to replicate various sensory functions of human skin, including the detection of temperature, matter, and wind. The core of the e-skin consists of copper (Cu) hot film elements, which is deposited on a flexible polyimide (PI) substrate and patterned into fingerprint-like structures. These Cu hot film elements are electrically heated to human body temperature and dynamically adjust their power based on the thermal conductivity of contacted materials, thus enabling matter recognition. Additionally, Cu cold films are used to sense ambient temperature. Wind sensing is achieved by monitoring power variation caused by convective heat transfer between different Cu hot films. Fabricated using an in-house MEMS process, this e-skin accurately distinguishes various materials [including air, PI, stainless steel, and iron (Fe)] and exhibits outstanding sensitivity for temperature measurement, with an ambient temperature measurement error of < 0.7 K and power variation of < 6.7% during coupling tests. Furthermore, leveraging its array structure, the e-skin is also capable of determining the object shape and wind direction by detecting output variations across different sensing units. In short, this multimodal e-skin will be a promising sensing system that can mimic human activities to enhance the thermal perception capabilities of robotics.