PANI E-skin Inspired by Microridge Structure and the Collaborative Mechanism of Mechanoreceptors for Elderly Health Monitoring and Intelligent Recognition of Abnormal Plantar Pressures

Human skin, with its microridge structure and synergistic mechanoreceptors, precisely perceives stimuli from touch to high pressures. Inspired by this, we designed a dual-layer ridge-structured polyaniline (PANI) e-skin that leverages PANI's reversible protonation and deprotonation and a pH-modulated strategy to form high- and low-resistance layers. The dual sensing layer enables the e-skin to achieve high sensitivity (maximum of 9.53 kPa^-1) and a wide pressure-sensing range (0.1-4000 kPa). In the low-pressure range, the e-skin exhibits high sensitivity and can precisely detect multiple characteristic peaks in the pulse waveform, clearly resolving the percussion wave (P-wave), tidal wave (T-wave), and diastolic wave (D-wave). At high pressures, the synergistic mechanism avoids signal saturation, ensuring accurate plantar pressure monitoring. The developed smart insole can precisely map plantar pressure and rapidly identify the normal foot type and four abnormal foot types (flat, cavus, valgus, and varus). Our developed PANI e-skin with superior sensing performance holds great promise for health monitoring and smart healthcare.