Ultrastable, Transparent and Skin-Attachable Temperature Sensors Based on NiO@Ag Core–Shell Nanowires

Flexible temperature sensors (TS) with ultrareliability, high transmittance, and exceptional skin conformability are urgently needed for the advancement of electronic skins. However, fabricating such high-performance sensor devices remains a formidable challenge. Herein, we propose an ultrastable, transparent and skin-attachable resistive TS, composed of a silver nanowire network with nickel oxide (NiO) shells embedded in a 3 μm-thick polyvinylidene fluoride (PVDF). The resultant NiO@Ag NWs/PVDF TS exhibits an exceptional optical transparency of 89.7% and high sensitivity (TCR of 0.30% °C–1). Particularly, after 400 heating–cooling cycles within the temperature range of 30–80 °C, the sensitivity of the sensor remains unchanged, demonstrating excellent reliability. More importantly, the sensor can be conformally attached to human skin due to its ultralow bending stiffness of 4.7 × 10–15 Pa·m4, offering favorable deformability. In addition, the introduction of the core–shell structure enhances the chemical stability of the sensor, enabling it to outperform conventional Ag NWs/PVDF TS even under harsh environments such as resistance to high temperature and humidity, acid/base, as well as strong oxidant. As a proof of concept, the NiO@Ag NWs/PVDF TS is successfully applied in wearable devices. It demonstrated a rapid response time of 0.6(1) s during human breathing monitoring. This work provides a scalable solution for applications in conformal wearable sensors and health monitoring devices.