Selective detection of hazardous VOCs using zeolite/Metglas composite sensors

Four different zeolite films of type FAU, LTA, MFI and b-oriented MFI were synthesized on top of magnetoelastic sensors in order to act as sensitive recognition layers for the detection of six different Volatile Organic Compounds, namely benzene, c-hexane, n-hexane, o- & p-xylene and ethyl-acetate. The FAU sensor shows the lowest minimum detection limits down to 6 ppm for o-xylene but lacks selectivity. The LTA sensor shows great selectivity towards the xylene isomers. Finally the randomly oriented MFI shows the greatest sensitivity of ∼180 ppm to n-hexane compared to all other sensors, and presents the opposite behavior to o-xylene and p-xylene compared to the b-oriented MFI sensor. The adsorption induced stresses affect the sensor response with the highest impact observed in the case of random oriented MFI under n-hexane exposure.