Long-lived solid state perchlorate ion selective sensor based on doped poly(3,4-ethylenedioxythiophene) (PEDOT) films

This work describes the development and fabrication of stable potentiometric solid state sensors for the perchlorate ion (ClO4−) based on doped poly(3,4-ethylenedioxythiophene) (PEDOT) films. PEDOT, one of the most promising conducting polymers, is extremely stable in its oxidized state. Using PEDOT(ClO4−) films as sensing material in ion selective electrodes presents a unique opportunity to create sensors having a longer lifetime compared to analogous sensors, such as those created using doped polypyrrole. Over the 8 month period of this study, the PEDOT(ClO4−) sensors exhibited a stable, linear response spanning at least five orders of magnitude in concentration (1 M to 1 × 10−5 M perchlorate) with near-Nernstian slopes approaching −59 mV/decade of ClO4− concentration and a limit of detection of 5 × 10−6 M. Carbon fibers and pencil leads were employed as alternative and inexpensive substrates for EDOT polymerization, addressing problems with the sensor's form (miniature size, flexibility) and cost.