Washable and breathable nonwovens-based flexible sensor by impregnating UiO-66-NH2/MoS2/Ag for detection of ammonia

The flexible ammonia sensor can detect the ammonia content in the air or the exhaled gas of humans, but the commonly used sensors have poor breathability and washability, so they are not suitable for direct contact with human skin. In this work, based on the excellent flexibility and permeability of nonwovens, UiO-66-NH 2 /MoS 2 @nonwoven (UMN) and UiO-66-NH 2 /MoS 2 /Ag@nonwoven (UMAN) gas sensors were prepared by loading self-prepared UiO-66-NH 2 /MoS 2 (UM) and UiO-66-NH 2 /MoS 2 /Ag (UMA) onto microfiber nonwovens. The results show that UMN and UMAN gas sensors exhibit high selectivity toward ammonia gas. The response values of UMN and UMAN demonstrate a consistent linear trend within the ammonia concentration range of 1–50 ppm and reach 43 % and 47 % at 1 ppm respectively. The response variations of the sensors before and after bending are below 4 %, demonstrating excellent bending stability. After washing for 24 h, the gas sensing performance shows nearly no change, indicating that they both have good reusability and washability. However, the sensors exhibit limited thermal and humidity stability. Given the challenges such as poor breathability and insufficient biocompatibility faced by traditional flexible gas sensors, UMN and UMAN sensors have emerged as highly promising alternatives with distinct advantages.