Reversible chemocapacitor system based on PDMAEMA polymers for fast sensing of VOCs mixtures

A sensing system, based on tailor-made qPDMAEMA polymers, with the ability to discriminate between methanol and ethanol vapors in the presence or absence of humidity without the need of a separation column and at room temperature is designed and implemented. The miniaturized sensing system is comprised of four polymer coated planar capacitors along with the readout electronic module. The capacitors are fabricated with mainstream microelectronic/micromachining processes forming a planar InterDigitated Electrodes outline with 1 μm critical dimension. Tailor-made, hydrophilic homopolymers and a copolymer based on poly((2-dimethylamino)ethyl methacrylate), synthesized via GTP and quaternized with either methyl iodide or 1-(chloromethyl)naphthalene were used as the sensing layer and were compared to a hydrophobic, commercially available polymer. The sensing system was evaluated upon exposure to humidity, volatile organic compounds and binary mixtures of the latter. Data processing with Principal Component Analysis (PCA) highlights the ability of the proposed sensing system to discriminate between polar analytes, and more importantly between low molecular weight alcohol vapors, ethanol and methanol, in the presence of humidity.