Conducting polymer membranes for low activity potentiometric ion sensing

Area of Science:

• Electrochemistry
• Materials Science
• Sensor Technology

Background:

• Conducting polymer (CP) films are used as ion-sensing membranes and ion-to-electron transducers.
• CP-based sensors typically have high detection limits (10⁻⁴–10⁻⁵ M), hindering their practical applications.

Purpose of the Study:

• To investigate the cause of high detection limits in CP-based sensors.
• To develop a method for predicting and lowering the detection limits of CP membranes.

Main Methods:

• Theoretical analysis of spontaneous polymer charging/discharging processes.
• Development of a method to estimate parameters of spontaneous charge transfer.
• Application of galvanostatic polarization to compensate for spontaneous processes.
• Experimental validation using poly(pyrrole), poly(N-methylpyrrole), and poly(3,4-ethylenedioxythiophene).

Main Results:

• Spontaneous polymer charging/discharging processes are identified as the primary cause of high detection limits.
• A method for estimating charge transfer parameters and predicting detection limits was established.
• Galvanostatic polarization was demonstrated to effectively lower the detection limits of CP membranes.
• Experimental results align well with the theoretical predictions of the model.

Conclusions:

• Understanding and controlling spontaneous charge transfer is crucial for optimizing CP-based sensors.
• Galvanostatic polarization offers a viable strategy to enhance the sensitivity of conducting polymer ion sensors.