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

Abstract

A surface acoustic wave (SAW) formaldehyde gas sensor was fabricated on a 42°75' ST-cut quartz substrate, with a composite sensing layer of zeolitic imidazolate framework (ZIF)-8 on polyethyleneimine (PEI)/ bacterial cellulose (BC) nanofilms.The addition of snowflake-like ZIF-8 structure on the PEI/BC sensitive film significantly improves the hydrophobicity of the SAW sensor and increases its sensitivity to formaldehyde gas. It also significantly increases surface roughness of the sensitive film. The hydrophobic nature of ZIF-8 prevents water molecules from entering into the internal pores of the BC film, thereby avoiding a significant mass loading caused by humidity when the sensor is used to detect low-concentration formaldehyde gas. The Zn 2+ sites at the surface of ZIF-8 improves the sensor's response to formaldehyde gas through enhanced physical adsorptions of gas molecules. Experimental results show that the ZIF-8@PEI/BC SAW sensor has a response (e.g., frequency shift) of 40.3 kHz to 10 ppm formaldehyde gas at 25℃ and 30% relative humidity (RH). When the relative humidity is increased from 30% to 93%, the response of the sensor only varies ~5%, and the change in response is negligible at medium humidity levels (~50 to 60% RH).

Paving the Way for a Green Transition in the Design of Sensors and Biosensors for the Detection of Volatile Organic Compounds (VOCs)

“…Other recent sustainable approaches for the preparation of sensors for formaldehyde detection include the use of largely available and inexpensive materials such as tin and zinc [ 121 , 122 , 123 , 124 , 125 , 126 , 127 , 128 ], the second most abundant element in the Earth’s crusts, i.e., silicon [ 129 , 130 ], the use of biomass-derived materials, such as bacterial cellulose [ 131 ] or egg-white [ 132 ].…”

Surface Acoustic Wave Devices Based on Graphene Oxide/Au Nanorod Composites for Gas-Phase Detection of 2,4,6-Trinitrotoluene

“…However, this detection method depends more on improving the accuracy of the SAW device, which demands additional processing requirements and increases sensing costs. Therefore, previous studies have explored sensing materials with selectivity, high adsorption, long-term stability, and reliability as sensitive layers combined with the SAW device to develop a novel sensor. , …”

“…Therefore, previous studies have explored sensing materials with selectivity, high adsorption, long-term stability, and reliability as sensitive layers combined with the SAW device to develop a novel sensor. 32,33 Polymers, 34 carbon-based nanomaterials, 35 metal nanostructures, 36 and their composites 37 are currently being used as materials for developing sensitive layers that are used in the SAW device. Graphene oxide (GO) is a promising sensitive layer for various gas sensors, owing to its attractive sp 2 -bonded nanostructure, large specific surface area, abundant oxygencontaining functional groups, and easily functionalized surface.…”