Humidity effect on the dithiol-linked gold nanoparticles interfaced chemiresistor sensor for VOCs analysis

1,6-Hexanedithiol-linked three-dimensional (3D) gold nanoparticles were synthesized by the exchange reactions between 1,6-hexanedithiol and n-octanethiol protected monolayer gold nanoparticles. A chemiresistor sensor was fabricated with the 3D nanoparticles as a sensing interface, and used for volatile organic compounds (VOCs) analysis. Both the resistance and the capacitance were measured. The sensor responses to humidity were investigated, and the humidity effect on the sensitivity to VOCs was stressed. Little humidity effect was observed in the responses to hydrophobic compounds such as toluene and ethyl acetate, but coordinate responses were observed in wet environment in the responses to hydrophilic compound such as ethanol. The performances of the 3D film-coated sensor were compared with the sensor coated with n-octanethiol protected monolayer gold nanoparticles. The cross-linking of the nanoparticles resulted in a decrease in the sensitivity, noise, response/recovery time, and the humidity effect.