Highly conductive surface-localized silver-enriched elastic conductors as a universal platform for skin electronics

Abstract

Skin electronics will play a pivotal role in the connected healthcare system that can extend healthcare beyond the clinical environment to personalized medicine integrated with patients' daily lives. This paper proposes a complete skin electronic platform (which encompasses three main parts: surface-localized silver-enriched elastic conductors (SSECs)), solderable copper pads and medical dressing. The high-performance SSECs was prepared through gravity induced sediments of silver nanoflakes, which not only exhibit extremely low sheet resistance of 4.8 mΩ/sq (the conductivity is 5.12 × 10⁶ S/m) but also superior stretchability (up to 300 %). The resistance variation of SSECs upon stretching is very small, which can satisfy the application requirements as analog circuit systems. Copper pads embedded in SSECs not only solve the problem of interconnecting with commercial rigid components and integrated circuits but also solve the problem of nagging issue of vulnerable connections between rigid and soft parts. The SSECs can be integrated into a permeable medical dressing by lamination, which is fully compatible and strong adhesion to the skin. As a demonstration, a skin circuit has been fabricated as the platform to integrate a temperature sensor and rigid circuitry to establish a skin temperature sensing system. Accurate temperature measurements can be maintained with only 0.3 % variation even at large wrist bending movements, adequately demonstrated the reliability and practicality of this innovative approach as a potentially universal platform and expected to have a broad application prospect.