Hydrophobic metal organic framework for enhancing performance of acoustic wave formaldehyde sensor based on polyethyleneimine and bacterial cellulose nanofilms

A surface acoustic wave (SAW) formaldehyde gas sensor was fabricated on a 42° 75? ST-cut quartz substrate, with composite sensing layer of zeolitic imidazolate framework (ZIF)-8 polyethyleneimine (PEI)/bacterial cellulose (BC) nanofilms. The addition snowflake-like ZIF-8 structure the PEI/BC sensitive film significantly improves hydrophobicity SAW and increases its sensitivity to gas. It also roughness film. hydrophobic nature prevents water molecules from entering into internal pores BC film, thereby avoiding significant mass loading caused by humidity when is used detect low-concentration Zn2+ sites at sensor's response through enhanced physical adsorptions molecules. Experimental results show that ZIF-8@PEI/BC has (e.g., frequency shift) 40.3 kHz 10 ppm 25 °C 30% relative (RH). When increased 30 93%, only varies ~ 5%, change in negligible medium levels (~ 50 60% RH).