Comparative CH4-sensing characteristic studies of PDMEB and PDMEB/In2O3 thin film sensors

In this paper, the poly-2,5-dimethoxyethynylbenzene (PDMEB) and poly-2,5-dimethoxyethynylbenzene/In₂O₃ were in-situ synthesized as gas sensing materials. The PDMEB/In₂O₃ nanocomposite was accessed by two procedures both relying on Pd catalysis: (1) The reaction of ethynyltri-n-buyltin replacing Br belonged to 1,4-dibromo-2,5-dimethoxy benzene, and (2) The step-growth polymerization of PDMEB through heating up the mixer, at the same time adding appropriate In₂O₃ nanoparticle. The morphology of films were characterized by scanning electron microscope(SEM). Compared with the pure PDMEB, it clearly appears that In₂O₃ components influence the morphology of the nanocomposite film, which leads to the variation of the response-recovery behavior of sensors. The PDMEB and PDMEB/In₂O₃ were deposited on the surface acoustic wave devices (SAW, whose corresponding operation frequency of baseline is 433.9MHz) to fabricate gas sensors by the spin-coating method. The sensors were exposed to various concentrations of CH₄ (in the range of 1%-5%) at room temperature, and the frequency shift of sensors were recorded. It was found that the PDMEB/In₂O₃ nanocomposite thin film sensor exhibited a better gas-sensing property than that of PDMEB thin film sensor.