Axopatch 200B "Floating" Mode

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ZVandy
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Axopatch 200B "Floating" Mode

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Is there a way to use the Axopatch 200B in a "floating" mode where it does not clamp either the voltage or the current? 

Suppose I was to reconstitute bacteriorhodopsin in an artifical bilayer (diphytanoyl phophatidylcholine, DPhPC) [refer to the diagram attached].  I understand that bacteriorhodopsin (BR) will pump protons (H+ ions) across the membrane if it is exposed to light.  I am not interested in the amount of current that the BR can produce as there seems to be plenty of literature on this, but I am interested in the membrane potential that the BR could produce.

Based on my current understanding, if I were to put such a system in the current clamp mode, the Axopatch 200B would apply a voltage (in the opposite direction of the BR pumping) in an attempt to keep the current across the lipid bilayer at 0 pA. Because of this voltage applied by the Axopatch 200B, the BR would have to pump against it.  Is my understanding incorrect?

If instead I were to put the system in voltage clamp mode, the Axopatch would adjust the voltage to keep the potential across the bilayer at 0 mV.  The problem is that I want the BR to be able to change the membrane potential by pumping the protons across the bilayer, but the membrane potential would be clamped at 0 mV in the voltage clamp mode.

So my question is if there is a way to use the Axopatch 200B in a "floating" mode, where I could measure the membrane potential (V_m) without clamping the current at 0?

Thank you in advance for your help with this!

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