Fully printed doped vanadium dioxide (M) nanoparticles-based temperature sensor with enhanced sensitivity for...

Global warming events worldwide have made temperature a crucial aspect of environmental monitoring. However, large-scale deployment of environmental temperature sensors to achieve high-resolution and real-time temperature mapping requires low cost and easily integrable sensors. Printing technologies offer low-cost manufacturing, however, the major challenge for printed electronics (PE) is the preparation of suitable functional inks with performance comparable to traditional electronics. Previously reported printed environmental temperature sensors have suffered from poor sensitivity without long-term outdoor studies which question their feasibility in real-world applications. In this work, we report synthesis of tungsten (W)-doped vanadium dioxide (VO₂) nanoparticles (NPs) and their preparation as inks to fabricate highly sensitive, high-resolution low-cost printed temperature sensors. The fully printed W-doped VO₂ temperature sensor demonstrates highest temperature coefficient of resistance (TCR) of 4.2% C^-1 with a resolution of 0.1 ⁰C in the range of 10-60 ⁰C. The long-term stability of the proposed sensor has been achieved using different packaging strategies, which demonstrate more than 100 days of reliable sensing in an outdoor environment with high humidity levels. Finally, a complete wireless readout system integrated with cloud data storage and a display server has also been developed for the as-printed temperature sensor to enable real-time environmental temperature monitoring.