A new chemiresistor sensor based on a blend of carbon nanotube, nano-sized molecularly imprinted polymer and poly methyl methacrylate for the selective and sensitive determination of ethanol vapor

An ethanol sensing composite was prepared by mixing of multi-walled carbon nanotube (MWCNT) as conducting element, nano-sized molecularly imprinted polymer (MIP) as recognition element and poly(methyl methacrylate) (PMMA) as an adhesive substance. This composite was applied as a chemiresistor sensor for the selective determination of ethanol. The type of polymeric adhesive was found to be very crucial in the selectivity of the sensing composite. Among ethyl cellulose, poly(epichlorohydrine), poly(methyl mathacrylic acid) and poly(methyl methacrylate), the later one was found to be the best option for using as the adhesive agent. The cross-linker/monomer ratio and the volume of ethanol, used in the MIP preparation, were found to be important in sensor selectivity and its response time. Moreover, the effect of the MWCNT and MIP content of the sensing composite on the performance of the sensor was investigated and proper amounts were chosen for them. The response of the prepared sensor was interestingly reversible and a relative standard error equal to 2.6% was obtained for 3 separate determinations. A short response time (about 1 min) was estimated for the sensor. The sensor showed linear response in the concentration range of 0.65–45.0 ppm. The detection limit was calculated to be 0.5 ppm (S/N).