Hi,
I am trying to create a model of three electrode system. One electrode (1E) is connected to both DC (2mA) and AC( sinusoid 0.05mA, 10Hz) positive terminal, another two are connected to the negative terminals; one from DC source and another from AC source. All electrodes are placed on a conductive gel medium. I am trying to mimic electrodes failure situation. So, while both sources are on, I slightly lifted the shared electrode (while maintaining at least a minimum contact with the conductive gel). I saw an immediate rise in voltage (both DC and sinusoidal) in the oscilloscope and multimeter. Then I brought back that shared electrode to its initial position while establishing good contact with the fluid. Then after 10 sec, I lifted the electrode connected to the negative terminal of the DC source, I saw small fluction in the DC voltage but sinusoid remained the same. I again brought back this electrode to its original resting postion. The third electrode in contact with the fluid and connected to the negative terminal of sinuosidal current source is left untouched. When I tried to plot this acquired condition with the first electrode failure and the second electrode failure condition, I got contrasting plots for DC resistance and AC resistance(impedance).
When the shared electrode was raised, DC resistance was tracked by the sinusoidal current(AC impedance) by a factor of 0.6 (DC to AC) but in the second electrode failure case, when the electrode connected to the negative terminal of DC source was slightly raised to maintain minimum electrode and gel contact, the AC impedance tracked DC resistance in an opposite direction. DC resistance was increasing while AC was decreasing with the same scale.
Is it true or something is wrong? My set up is perfectly fine and is tested. Is any of the current source (may be the sinusoid source) taking up the current from the DC source of something else might have happened?
From my experience, when the electrode connected to the negative terminal of DC is lifted, the voltage should shoot up so do the DC resistance but the AC should remain flat (unchanged).
Any suggestion?
Thanks
Stacy
I am trying to create a model of three electrode system. One electrode (1E) is connected to both DC (2mA) and AC( sinusoid 0.05mA, 10Hz) positive terminal, another two are connected to the negative terminals; one from DC source and another from AC source. All electrodes are placed on a conductive gel medium. I am trying to mimic electrodes failure situation. So, while both sources are on, I slightly lifted the shared electrode (while maintaining at least a minimum contact with the conductive gel). I saw an immediate rise in voltage (both DC and sinusoidal) in the oscilloscope and multimeter. Then I brought back that shared electrode to its initial position while establishing good contact with the fluid. Then after 10 sec, I lifted the electrode connected to the negative terminal of the DC source, I saw small fluction in the DC voltage but sinusoid remained the same. I again brought back this electrode to its original resting postion. The third electrode in contact with the fluid and connected to the negative terminal of sinuosidal current source is left untouched. When I tried to plot this acquired condition with the first electrode failure and the second electrode failure condition, I got contrasting plots for DC resistance and AC resistance(impedance).
When the shared electrode was raised, DC resistance was tracked by the sinusoidal current(AC impedance) by a factor of 0.6 (DC to AC) but in the second electrode failure case, when the electrode connected to the negative terminal of DC source was slightly raised to maintain minimum electrode and gel contact, the AC impedance tracked DC resistance in an opposite direction. DC resistance was increasing while AC was decreasing with the same scale.
Is it true or something is wrong? My set up is perfectly fine and is tested. Is any of the current source (may be the sinusoid source) taking up the current from the DC source of something else might have happened?
From my experience, when the electrode connected to the negative terminal of DC is lifted, the voltage should shoot up so do the DC resistance but the AC should remain flat (unchanged).
Any suggestion?
Thanks
Stacy
