The GUI is one shot (one full Cycle) for CV and SWV measurements.
The Voltage that is being swung is the WE to RE difference (WE to CE difference in 2-terminal mode example below), also known as the bias voltage.
- Bias Voltage = WE-RE (3-terminal mode, SC open, SRB closed)
- Bias Voltage = WE-CE (2-terminal mode, SC Closed, SRB open)
In CV mode the WE voltage is the voltage that is being stepped from Start voltage to Stop voltage. (start voltage is the DAC_A voltage setting in the example below, EIS DAC Select is used to select which DAC is connected to the WE electrode).
RE (3-terminal mode) or CE (2-terminal mode) is set by the voltage at the (+) CE Amp input. (DAC_B voltage in examples below).
So to calculate the Bias Voltage min (start) and Bias Voltage max o the “swing voltage” in 2-terminal mode,
- BiasV_Min = VWEstart - CE
- BiasV_Min = 0.4V – 1.4V = -1V
And
- BiasV_Max = VWEstop – CE
- BiasV_Max = 2.4 – 1.4 = +1V
Our device is unipolar as all voltages are above ground. The important thing to note is that the voltage range for a CV measurement is from VWEstart – VRE/CE to VWEstop – VRE/CE and does not need to be referenced to ground. For 3-Terminal mode replace CE with RE in equation above but note that you still use the DAC voltage set at the (+) CE Amp input.
Example:
To get a -1 to +1 CV range you can do the following:
Set Vref to 3.072V in Conversion tab.
Set the Start Voltage to 0.4V (VWE should always be at least 0.2V above ground)
Set the RE/CE voltage to 1.4V (DAC input to CE amp (+), this is the reference voltage with respect to the Working Electrode voltage)
Set the stop voltage to 2.4V (this is 0.9V below VDD (3.3V), typically need 0.6V overhead for Working Amp drive to FET)
Set the step size as needed.
Set the step time as needed.
The below configuration is for a 2-terminal measurement.
For a 3-terminal measurement check SRB Closed and uncheck SC Closed on both the Sensor Channel 1 tab and the EIS tab.