An on-chip chemiresistive polyaniline nanowire-based pH sensor with self-calibration capability.

A pH sensor based on chemiresistive polyaniline nanowires, which makes use of the pH responsive conductivity of the polymer, requires an electrochemical system during measurements in order to maintain its oxidation state. In this work, we have developed an integrated electrochemical device where a reference, a counter, and a pair of working electrodes are all fabricated on a single chip. The polyaniline nanowires are grown between this pair of working electrodes that are separated by a microscale gap. This device can easily be connected to the external circuit for potential control and current measurements. Taking advantage of the fact that polyaniline becomes insulating when it is fully oxidized or fully reduced, the pH sensor can be electrically reset by controlling the electrochemical potential of the polymer. This paper presents the pH sensing results and the performance of the resetting function of the developed integrated device.