From sensors to system-level integration: Flexible WO3/MoS2 heterojunction NO2 gas sensor

While flexible gas sensors have attracted increasing attention, studies that advance their development toward system-level applications remain very limited. Here, we report a flexible WO 3 /MoS 2 nitrogen dioxide (NO 2 ) sensor. Benefiting from the synergistic effect of WO 3 and MoS 2 , the sensor exhibits a remarkable 364.5 % response to 1 ppm target gas, along with excellent selectivity, stability, and humidity tolerance. Moreover, the device maintains stable sensing performance under repeated bending, confirming its mechanical robustness for wearable applications. To demonstrate practical utility, the sensor was built into an ambient system that provides continuous OLED readout and triggers audible buzzer alarms once the NO 2 concentration exceeds user-defined thresholds. This work not only highlights the excellent sensing performance of the WO 3 /MoS 2 heterojunction device but also demonstrates its strong potential for system-level deployment in real-world air quality monitoring and personal exposure warning scenarios.