Dear researchers,
Can you please provide me information which mode is the best to be selected when using potentiostat Biologic SP 200: floating or grounded mode? We are using three electrode system (RE - AgAgCl, WE - Pt wire and CE - Pt foil) and we have some problems with noise both in OCV and LSV methods. We checked all of the connections but the noise is still present, we also tried with different reference electrodes but no improvement.
Currently our potentiostat is in floating mode, should we change it to grounded mode, although it is written in the Instruction manual that this mode is for multi electrode configurations and we are not using something like that?
Finally, is it possible that if we use Faradaic cage our problems will be solved?
Best regards,
Sasho
In the context of a biologic potentiostat, the term “floating” refers to a specific connection mode.
1. Ground (GND): The ground is a reference potential from which other potentials can be measured. In most cases, it is set to 0 volts. BioLogic instruments are typically “grounded,” meaning that the ground of the channel board is directly linked to the earth through the power cord. This grounding is done for safety reasons and serves as a return path for current or to protect measured signals from external electric fields within a Faraday cage.
2. Floating Channel Board: In some cases, the ground is not directly connected to the earth ground. When the channel board is “floating,” it means that the ground is isolated from the earth ground. This configuration is generally used when the cell itself is directly connected to the earth. For example:
Measurements performed on a sample inside an autoclave. Measurements on pipelines.
By using a floating channel board, you prevent the formation of a ground loop, which can negatively impact measurement quality. Ground loops occur due to potential differences between different earth grounds, resulting in leakage current and disturbances in measurements. The floating channel board isolates the channel ground from the earth ground using an internal relay, allowing the channel board potential to “float.”
3. Switching Modes: The potentiostat can switch between grounded and floating connection modes. When grounded, the internal relay is closed, and a protective resistor limits the current passing through the ground. When floating, the internal relay opens, and the channel board potential is isolated from the earth ground.
Remember that only the channel board inside the potentiostat can be considered floating; the chassis is always connected to the earth ground. Some premium-range potentiostats offer a “floating” mode for specific applications1. Additionally, a green plug on the back panel of Bio-Logic potentiostats allows connecting a Faraday cage for shielding purposes.
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