Analyte discrimination with chemically diverse sensor array based on electrocopolymerized pyrrole and vinyl derivatives
The development of chemically diverse arrays has gained the attention of researchers due to their anticipated capacity to mimic the function of olfactory receptors in the mammalian olfactory system. A major hurdle facing the field is the limited ability to generate large numbers of different sensing elements out of the relatively limited number of conducting polymers. In this work, chemically distinct electrocopolymerized sensors were created with pyrrole by using different substituted vinyl groups (e.g., styrene, m-styrene, 4-chlorostyrene, 4-chloromethylstyrene, 4-t-butylstyrene, 4-t-butoxystyrene, divinyl benzene and vinyl pyridine) as monomers. Copolymer films were grown at different potentials that created an additional level of sensor diversity by altering the relative amount of each of the components. By controlling the deposition conditions in this way, as well as setting different redox potentials to the films after growth changes the copolymer's composition and the amount of dopant anion that is incorporated into the sensing films respectively. The composition of the sensing films was also altered by changing the dopant-type during copolymer growth, thereby providing another mechanism for varying the chemical nature of the sensing materials. The chemical diversity among the 27 different sensing polymers used in this work is demonstrated with differential partitioning of 12 analytes, ranging from alcohols and solvents to fuels. This process of generating significant numbers of chemically distinct sensors represents a significant advancement in the efforts to approach the number of olfactory receptors in mammals. The fact that the sensing polymers can be electropolymerized onto very small conducting contacting electrodes shows that this approach is compatible with integrated circuit technology.