Potentiometric ion-selective membrane electrodes (ISMEs) have been extensively used for ion analysis in clinical, environmental, and industrial fields owing to negligible effect of sample turbidity, fast response time, and ease of miniaturization. Plasticized poly(vinyl chloride) (PVC) is a common matrix to prepare ISMEs due to its good compatibility with ionophores, easy handling, and chemical inertness. However, Plasticized PVC for all-solid-state-type sensors has been limited due to weak adhesion to most of electrode surfaces, eventually detracting the sensor's lifetime. To enhance the sensor's lifetime, many techniques have been applied for sensor preparations, including mechanical fastening of the membranes, chemical attachment of sensing membranes to solid surfaces, and use of adhesive polymers as a matrix. Even though those techniques have advanced in membrane adhesion to the metal surface and lifetime, there are some limitations such as sophisticated fabrication and/or compromised electrochemical performance. Silicone rubber (SR) as a matrix has attracted attention as an alternative matrix owing to its strong adhesion to various metallic electrode surfaces. Unfortunately, SR based ISEs have not been widely applied because of poor reproducibility and severe noise level in the sensor signal which results from the SR's high membrane resistance. Herein we employ a solvent-soluble conducting polymer to reduce the SR based ion selective membrane resistance. Moreover, incorporation of a conducting polymer into the ion-selective SR membrane (i.e., single piece) may be allowed to improve ion-to-electron transduction between two different phases, i.e., the polymeric sensing membrane and the metallic electrode. A series of solvent-soluble benzobisthiazole- and ethylenedioxythiophene-type conducting polymers are used to prepare all-solid-state ion-selective SR membranes. The electrochemical properties of ISEs are evaluated in terms of sensor's drift, noise levels, impedance, selectivity, and lifetimes.

Single-piece all-solid-state ion-selective membrane electrodes doped with solvent-soluble conducting polymers

246th National Meeting (2013)

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