Skin-Conformal Ag Flake-Decorated PEDOT:PSS Sensor Arrays for Spatially Resolved Body Temperature Monitoring

Rapid and spatial temperature measurement on the skin is essential for detecting localized physiological anomalies, such as inflammation or circulatory issues, while providing insights into thermoregulation. Skin-conformal temperature sensors, with ultra-flexible designs, enable precise and comfortable measurements, supporting real-time monitoring, early diagnosis, and effective intervention. However, achieving rapid and spatial skin-conformal temperature sensor arrays that simultaneously maintain high sensitivity under extreme mechanical stresses remains a significant challenge. This work introduces a skin-conformal temperature sensor array based on a composite of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and Ag flakes, fabricated on a 2-µm-thick parylene-C substrate. A simple mixing process achieves uniform dispersion of Ag flakes, enhancing electrical conductivity to 2.04 kS cm^-1. The sensor demonstrates a temperature coefficient of resistance of -2.02%/°C (30-50 °C), a resolution of 0.5 °C, and a rapid response time under 0.41 s per 5 °C change. It endures over 1000 cycles of 200% strain and performs reliably under 3 µm bending radii. Demonstrating high-resolution sensitivity and spatial temperature mapping through letter pattern recognition, the sensor shows promise for applications in body temperature monitoring, thermal imaging, and early diagnosis of temperature-related health conditions.