A humidity sensor based on ionic liquid modified metal organic frameworks for low humidity detection

Low humidity detection has always been a challenge in the field of humidity detection. Humidity sensors base on ionic liquid modified metal organic frameworks (MOFs) derived polymer films were prepared in this work. The ionic liquid ligand was uniformly introduced in the frameworks of UIO-66 to enhance the hydrophilicity of sensing materials, the caused defects sites are beneficial for adsorption and desorption, and the MOFs based functional films were easily obtained by in situ photoinduced thiol-ene click reaction. The obtained humidity sensor exhibits a linear response in low relative humidity (RH) range (5% RH - 30% RH) with a tiny humidity hysteresis (~0.2% RH) and short response time to humidity change (response/recovery time is 0.6 s/1.7 s, respectively). ● Humidity sensors based on ionic liquid modified UIO-66 derived polyelectrolyte films were prepared. ● The sensors were prepared facilely in situ on the electrodes by thiol-ene click polymerization in batches. ● The sensor presents linear response under low humidity (5% RH - 30% RH) with a small hysteresis and fast response speed. ● The introduction of ILs and the resulting defect sites are the reasons for effective low humidity detection.