, takeo Shiba, takao nishikawa & Shizuo tokito * facile fabrication and high ambient stability are strongly desired for the practical application of temperautre sensor in real-time wearable healthcare. Herein, a fully printed flexible temperature sensor based on cross-linked poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was developed. By introducing the crosslinker of (3-glycidyloxypropyl)trimethoxysilane (GOPS) and the fluorinated polymer passivation (CYTOP), significant enhancements in humidity stability and temperature sensitivity of PEDOT:PSS based film were achieved. The prepared sensor exhibited excellent stability in environmental humidity ranged from 30% RH to 80% RH, and high sensitivity of −0.77% °C −1 for temperature sensing between 25 °C and 50 °C. Moreover, a wireless temperature sensing platform was obtained by integrating the printed sensor to a printed flexible hybrid circuit, which performed a stable real-time healthcare monitoring. Body temperature is an essential vital parameter reflecting the physiological activities. Monitoring of body temperature provides insight into human health conditions, such as cardiovascular condition, wound healing, pulmonological diagnostics, and syndromes prediction 1-4. Therefore, the flexible temperature sensor is highly desired to realize personal healthcare devices, which enable real-time monitoring of an individual's health state 5,6. Many efforts have been made to develop flexible temperature sensors, which mainly contain three types: pyroelectric detectors 7,8 , resistive temperature detectors (RTDs) 9,10 , and thermistors 11. Among them, the thermistor which relies on the thermo-resistive effect of sensing material is widely used, due to its simple device structure, fast response, and wide sensing range 12,13. Various thermistor materials have been developed and investigated, including composites of conductive filler with polymer, and temperature sensing conductive materials such as silver nanowire (AgNW) 14,15 , carbon nanotubes (CNTs) 16 , reduced graphene oxide (rGO) 17,18 , and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) 19,20. However, most of these studies focused on improving the sensitivity and mechanical performance of temperature sensors, while their ambient stability, especially humidity stability, has rarely been considered. Additionally, the development of wearable temperature sensors via simple fabrication still a big challenge. Since the use of wearable devices inevitably exposed to ambient humidity, it is of great interest to develop a facile fabricated humidity-resistant temperature sensor. In contrast to its counterparts, PEDOT:PSS has been proven as a promising candidate for the wearable temperature sensor, not only owing to its outstanding mechanical properties and turntable electrical characteristics, but also the superior in simple, patternable, and high reproducible fabrication, such as printing 21,22. However, as a water-soluble polymer, the resistance of PEDOT:PSS also be easily affecte...