Four-Probe Membrane Conductivity Cell

Four-Probe Membrane Conductivity Cell is designed to study ionic conductivity of cation exchange membranes and anion exchange membranes at various relative humidity and temperature conditions. In the four-probe conductivity cell configuration, the current-generating electrodes are separated from the voltage measuring probes. The two inner probes serves as voltage sensors and the two outer probes as AC current injectors. With the implementation of the electrochemical impedance spectroscopy technique, one can extract the ionic resistance (which is the inverse of the ionic conductivity) from an equivalent circuit model of the proton exchange membrane. Four-probe method can separate PEM-electrode interfacial impedance from the PEM impedance and is appropriate for low ionic resistance measurements. Some of the essential literature is provided here to support the researchers and end users using this conductivity cell.

• Material: The main body of the conductivity cell is manufactured from PEEK (poly ether ether ketone) and four-probe elements are manufactured from high purity platinum.
• Versatile Testing: This conductivity cell can be used for measuring proton conductivity for proton exchange membranes or hydroxyl ion conductivity for anion exchange membranes.
  
• Operating Principle: This is a four-probe based ionic conductivity measurement cell. The users are recommended to review the basics of four-probe conductivity basics and electrochemical impedance spectroscopy to accurately measure the ionic conductivity of the membranes they are planning to experiment with. 
• Assembly: After placing the membrane sample on the platinum probes, the four corners should be securely fastened by torquing down the screws supplied with the conductivity cell.

Four-Probe Conductivity Relevant Literature

A PhD dissertation by Chenzhao Li, entitled "Study of Structure-Property-Performance Of the Polymer Electrolyte Membrane Fuel Cells (PEMFCs)" investigates the use of four-probe conductivity cell to measure proton conductivity of various proton exchange membranes.

An article by Lee et al., entitled "Importance of Proton Conductivity Measurement in Polymer Electrolyte Membrane for Fuel Cell Application", investigates the use of two-probe and four-probe in a thermo- and hygro-controlled chamber to study the proton conductivity of Nafion 212, Nafion 115, and Nafion 117 membrane and formulates a precise impedance measurement system.

An article by Xie et al., entitled "Discrepencies in the Measurement of Ionic Conductivity of PEMs Using Two- and Four-Probe AC Impedance Spectroscopy", details the comparison of two-probe and four-probe measurement with the help of AC Impedance Spectroscopy to investigate the proton conductivity of Nafion 115 and discusses pros/cons of both measurement protocols.

An article by Yadav and Fedkiw, entitled "Analysis of EIS Technique and Nafion 117 Conductivity as a Function of Temperature and Relative Humidity", details the two-probe EIS technique to measure the in-plane proton conductivity for Nafion 117 in the temperature range of 25-80 deg C and 10-100% relative humidity.

3-5 weeks lead time is to be expected.

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