Hi, I noticed something that got me thinking and I cant work out which is the most likely explanation. I have posted this pic before and again it isnt the exact vessel being used but they are very very similar.
Alot of the top parts that are stainless steel are actually sealed with a O ring, so they are in effect isolated electrically from the main top. The bottom collar is made from an insulating material (I dont know what the material is though), the one I am using also has a rubber collar on it and the stainless steel top sits on another airtight seal.
I am keeping these vessels in a light tight room, they are heated and contain organic material including some fruit. I wanted one of them in the chain to be slightly more insulated than the others after inoculating it, I placed some aluminum foil around the glass part of the body to do this.
While general faffing about trying to get a TDS probe working that sits in the vessel I noticed on my DMM that if I touch the central stirring mechanism with one probe and the foil with the other I get a voltage reading (800mV).
The contents are buffered to pH 4.5-5, my first thoughts were it was acting like a capacitor, but the voltage held for a around 15mins before I had to go and do something else. So now I am unsure if its creating a voltage or is indeed acting like a capacitor or maybe both? It dosnt matter so much in regards to the experiment, however when I measured it today the voltage had dropped to 40mV and didnt hold long, there has been biological changes to the contents so now I am wondering if this effect is worth looking into as a way of monitoring what is going on inside the reactor.
Like I say it isnt massively important to me but I would like some input on what people think I am seeing, if its behaving like a battery then it might be useful to me as another non invasive way to measure activity, if its simply a capacitor then it probably isnt as useful and it has pH probes etc inside and therefore I can see various ways a charge would build up.
So to cap
Stainless steel core isolated from the other parts, a organic acidic medium of thickish consistency, then a glass wall and aluminum layer on the outside.
Hmm might be a kind of battery as the foil was touching another part of the top and now it isnt so maybe now its more like a cap
Alot of the top parts that are stainless steel are actually sealed with a O ring, so they are in effect isolated electrically from the main top. The bottom collar is made from an insulating material (I dont know what the material is though), the one I am using also has a rubber collar on it and the stainless steel top sits on another airtight seal.
I am keeping these vessels in a light tight room, they are heated and contain organic material including some fruit. I wanted one of them in the chain to be slightly more insulated than the others after inoculating it, I placed some aluminum foil around the glass part of the body to do this.
While general faffing about trying to get a TDS probe working that sits in the vessel I noticed on my DMM that if I touch the central stirring mechanism with one probe and the foil with the other I get a voltage reading (800mV).
The contents are buffered to pH 4.5-5, my first thoughts were it was acting like a capacitor, but the voltage held for a around 15mins before I had to go and do something else. So now I am unsure if its creating a voltage or is indeed acting like a capacitor or maybe both? It dosnt matter so much in regards to the experiment, however when I measured it today the voltage had dropped to 40mV and didnt hold long, there has been biological changes to the contents so now I am wondering if this effect is worth looking into as a way of monitoring what is going on inside the reactor.
Like I say it isnt massively important to me but I would like some input on what people think I am seeing, if its behaving like a battery then it might be useful to me as another non invasive way to measure activity, if its simply a capacitor then it probably isnt as useful and it has pH probes etc inside and therefore I can see various ways a charge would build up.
So to cap
Stainless steel core isolated from the other parts, a organic acidic medium of thickish consistency, then a glass wall and aluminum layer on the outside.
Hmm might be a kind of battery as the foil was touching another part of the top and now it isnt so maybe now its more like a cap
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