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Using a Source Measure Unit to Perform Open Circuit Potential of an Electrochemical Cell

In a previous blog within the Electrochemistry series, we demonstrated how source-measure units (SMUs) can be used as a Potentiostat for Cyclic Voltammetry and other similar applications. Another great use for a source-measure unit like the Model 2450-EC and 2460-EC, is the measurement of open circuit potential (OCP) of an electrochemical cell.  The OCP of an electrochemical cell is a voltage measurement made between the reference (RE) and working (WE) electrodes. Measuring open circuit potential requires a voltmeter, like an electrometer, with high input impedance to measure the voltage with no current or voltage applied to the cell. Because of their high input impedance, source-measure units are well suited for open circuit potential measurements when configured in a 4-wire configuration (Figure 1). In this setup, the instrument is configured to measure voltage and source 0 Amperes.  As an added bonus if OCP is measured before performing cyclic voltammetry, there is no need to rearrange any test leads manually between measurements because the electrochemical instrument can automatically change functions internally.


Figure 1. Using a source-measure unit to measure the open circuit potential of an electrochemical cell

The 2450-EC and 2460-EC models now include an easy to use preprogrammed application for measuring OPC.  Other applications that are included with these models include linear scan voltammetry, cyclic voltammetry, chronoamperometry, chronopotentiometry, and current and voltage square wave with measuring.  These applications takes advantage of the 2450-EC and 2460-EC touch screen interface to walk a user through the setup in a few simple steps which can have the user up and measuring in minutes.  Up to 10,000 measurement samples can be taken at a time and stored to a convenient thumb drive for later analysis. 

For more information on the products discussed in this blog, click on the following links:

Further information on using the Model 2450-EC or 2460-EC Potentiostats for cyclic voltammetry can be found in the application note, “Performing Cyclic Voltammetry Measurements Using Model 2450-EC or 2460-EC Electrochemistry Lab Systems.”



Mary Anne Tupta is a Senior Applications Engineer for the Keithley product line at Tektronix. She earned a B.S. in physics/electronic engineering and an M.S. in physics from John Carroll University. She is a member of Keithley’s electrochemistry team.