Design and Characterization of a Gel-Based Thermal Contact Sensor for Approximating Human Finger Heat Transfer.

Thermal responses at the skin-material interface play an important role in human touch perception and material recognition. This study presents the design and characterization of a gel-based thermal contact sensor developed to approximate the transient heat-transfer responses of the human finger during material contact. The sensor incorporates a compliant, finger sized gel interface and an integrated heating system that reproduces an initial skin-like temperature condition at contact onset. The design is motivated by limitations of conventional rigid contact thermal sensors, including unstable contact conditions and discrepancies from human finger responses. Compared with a previous glass-based design, the proposed sensor improves measurement stability and achieves closer correspondence to human finger thermal responses, particularly for materials with mid-range thermal effusivity. However, the sensor exhibits faster and larger temperature changes than the human finger for high effusivity materials, highlighting the challenges of reproducing human-like interfacial heat transfer. We discuss possible con tributing factors, including thermal contact resistance, surface conformity, and the absence of fingerprint-like microstructure in the gel interface. The proposed system is positioned as a biomimetic thermal sensing platform for capturing human-like thermal contact responses under controlled conditions, with potential future applications in haptic interface evaluation, robotic material sensing, and data-driven material recognition systems.