Single chip interdigitated electrode capacitive chemical sensor arrays

In this paper the design considerations, fabrication and first evaluation results of a capacitive type single chip chemical sensor array based on interdigitated electrode structure is presented. The electrode arrays have been fabricated with conventional semiconductor processes. The final structure consists of four interdigital capacitive sensors each one coated with a different polymer sensitive film by using only successive lithographic steps. The array sensors have good response to controlled concentrations of volatile organic compounds (∼35fF, ∼7fF, ∼12fF for the PHEMA covered sensor when exposed to 100 ppm of water, methanol and ethanol vapors and ∼2.5fF, in the case of 100 ppm of toluene vapors for the PDMS covered sensor).