Multichannel Techniques
Multichannel techniques are available on the epsilon by the addition of the optional bipotentiostat board. Bipotentiostat experiments can be run for cyclic voltammetry, chronoamperometry and DC amperometry.
The Change Parameters dialog box for multichannel cyclic voltammetry (MCCV) is shown in Fig1. Setting the parameters for Channel 1 is described in detail in the section on cyclic voltammetry.
Figure 1. Change Parameters dialog box for multichannel cyclic voltammetry.
There are two options available for Channel 2:
a) Fixed potential. Channel 2 is held at a set potential value, as defined by the Applied Potential. The Potential Scan box should not be checked. Note that the current sensitivity (Full Scale) for Channel 2 must also be specified. Typical output from a "scan-hold" experiment is shown in Fig2.
Figure 2. Typical data for a scan-hold multichannel cyclic voltammetry experiment.
b) Potential scan. Channel 2 is scanned over the same potential range and at the same scan rate as Channel 1. The Potential Scan box must be checked. Note that the current sensitivity (Full Scale) for Channel 2 must also be specified. Typical output from a "scan-scan" experiment is shown in Fig3.
Figure 3. Typical data for a scan-scan multichannel cyclic voltammetry experiment.
The Change Parameters dialog box for multichannel chronoamperometry (MCCA) is shown in Fig4. Setting the parameters for Channel 1 is described in detail in the section on chronoamperometry.
Figure 4. Change Parameters dialog box for multichannel chronoamperometry.
There are two options available for Channel 2:
a) Fixed potential. Channel 2 is held at a set potential value, as defined by the Applied Potential. The Potential Scan box should not be checked. Note that the current sensitivity (Full Scale) for Channel 2 must also be specified.
b) Potential step. The step potentials and times for Channel 2 are the same as those used for Channel 1. The Potential Scan box must be checked. Note that the current sensitivity (Full Scale) for Channel 2 must also be specified. Typical output from a "step-step" experiment is shown in Fig5.
Figure 5. Typical data for a step-step multichannel chronoamperometry experiment.
The Fast External Start option is unique to multichannel chronoamperometry. In this option, an external trigger-in is required to start the countdown of the Quiet Time and the cell is at open circuit potential during the Quiet Time rather than at Initial Potential. This allows the effect of the homogeneous reaction time (i.e., the Quiet Time) on the electrochemical response to be determined.
The Change Parameters dialog box for multichannel DC amperometry (MCA) is shown in Fig6. Setting the parameters for Channel 1 is described in detail in the section on DC amperometry. The fixed potential for the second channel can be automatically set to the same value as the first channel (if E Same as Channel 1 is checked), or a different value can be entered.
Figure 6. Change Parameters dialog box for multi-channel amperometry.
