Multiple artificial mechanoreceptor-embedded waterproof ciliated E-skin via direct-ink-writing vertically 3D printing toward health management of seafarers

Abstract

Prolonged exposure to high-humidity environments aboard ships presents unique challenges for continuous physiological monitoring of seafarers as conventional wearable sensors often suffer from moisture-induced signal instability. To address this, we present a waterproof ciliated electronic skin (WCES) inspired by epidermal hair and mechanoreceptors in skin, exhibiting a water contact angle of 113.7° and a pressure sensitivity of 14.9 kPa⁻¹, achieved through a synergistic design combining microcilia-induced stress concentration and dual-mode mechanotransduction of fillers. The embedded carbon black and ionic liquid, respectively, mimic fast-adapting and slow-adapting receptors via particle sliding and directional ion migration under pressure. To fabricate microcilia with a high-aspect-ratio, we develop a vertically 3D printing technique enabled by a volatile solvent to formulate the constituent material into a high-yield-stress ink. Therefore, the sensing performance of printed WCES is stable in humid environments, with less than 7.75% signal degradation after prolonged soaking. Integrated into a health monitoring system suitable for seafarers' environments, the WCES successfully distinguishes pulse signals from individuals in different physiological states with an accuracy of 97.58% using a random forest model. This work offers a robust platform for reliable physiological sensing in maritime environments and highlights a promising route toward real-world deployment of high-performance electronic skin technologies.