Development of a haptic sensor for monitoring skin conditions

This paper is a study on the development of a haptic sensor system for monitoring skin conditions. The sensor is an assembly of layered media. The base of the sensor is a stainless plate, on which a sponge rubber, a PVDF film with electrode patches, a protective surface layer of acetate film and a gauge are stacked in sequence. The sensor is attached to the forefinger and pressed against the surface of the skin. It is then slid over the skin to collect surface morphological features. Through the fundamental experiment using the artificial objects, two evaluation parameters characterizing skin conditions are determined. One is the variance of the signal processed with a wavelet analysis, which is the index of roughness. The other is a parameter showing the dispersion of power spectrum density in the frequency domain, which is the index of softness. The sensor system is then applied to the clinical test of skin with various conditions. Results show that the sensor output well describes the skin conditions and represents the subjective evaluations of dermatologist.