Electrophys - Time integral of voltage

[dom_stb]

Hello,

I have recorded voltage signals (in the time domain) using standard electrophys amplifiers. The voltage is that of an electrode inserted in a plant stem as charged objects are brought close to, then into contact with the flower.

I was wondering about the significance of the time integral of voltage: It is not clear to me what, if any physical significance this has.

Op-amp based voltage integraters in electronics measure the total electric flux through the amplifier - or so i understand it. Does this apply to the signals I measure?

I know if resistance is constant, voltage is proportional to current so the integration of V dt is proportional to charge, but without a reliable value for R this is useless to me.

I want to know exactly what quantity the integration of Vdt gives.
Any ideas?
Regards,
Dom.

 

[SW VandeCarr]

Hello,

I was wondering about the significance of the time integral of voltage: It is not clear to me what, if any physical significance this has.

I want to know exactly what quantity the integration of Vdt gives.
Any ideas?
Regards,
Dom.

It should give the total charge (in Coulombs) across a membrane in time t given R and V are known. I'm not sure you really need to know this.

In most cases, you want to know Vmax and the shape of the voltage curve.

So for a time constant $$\tau=r_{m}c_m$$ where r is the resistance and c the capacitance of the membrane:

rise $$V(t)=Vmax(1-e^{-t/\tau})$$
fall $$V(t)=Vmax(e^{-t/\tau})$$

 

[dom_stb]

Thanks very much, that's helpful.

What I am measuring is really the transfer of charge (though i am measuring the voltage) between the object and the flower. It won't necessarily follow neuronal models, but it will be nice to see if te shape can be charactarised by any of these equations.

Thanks again.