Master transduction curve for field-structured chemiresistor calibration.

Chemiresistors are gas sensors for volatile organic compounds that are composed of conducting particle networks in a polymer matrix. In the presence of an analyte that is compatible with the polymer phase, the sensor conductance decreases as the analyte is absorbed, eventually reaching a steady-state value that is a measure of the analyte's concentration. The response curve, which is the relationship between steady-state conductance and analyte activity (normalized concentration), is strongly dependent on both the chemical affinity of the analyte for the polymer and the stress field within the chemiresistor composite. Calibration of an individual sensor would seem to necessitate mapping out the response curve for each analyte of interest, a tedious and expensive proposition. In a recent paper, we have shown that the transduction curve of any particular sensor is a function of polymer swelling alone, regardless of the chemical nature of the analyte. This master transduction curve implies that sensor calibration requires only a knowledge of the polymer mass-sorption isotherm for any set of analytes of interest, data that can be collected once and for all. Any single analyte can then be used to calibrate the response of a particular sensor as a function of analyte activity, and the response to other analytes can be predicted. As a corollary, a calibrated sensor can be used to determine the mass-sorption data for any other analyte of interest. In this paper, we provide a detailed description of the construction of the master transduction curve, show how this curve can be used to measure polymer sorption with a calibrated chemiresistor, and demonstrate the use of a single analyte to calibrate sensors of disparate sensitivities and predict their response to two other analytes.