Hi I'm an electrical engineer but have not seen this problem before. I'mn trying to measure/calculate the resistance of a liquid.
Background: I'm working on an electronic device that can come in contact with a liquid. Unintentional, can be avoided but is not considered a big deal. It's easy to clean and does not corrode/hurt the print.
What I noticed is that it misbehaves when in contact with the liquid. I've found that the liquid sometimes was conductive enough to cause a small bias current on a transistor, introducing a large bias on the output. Just enough to break the function.
Problem: I want to calculate the resistance of this liquid. But I've not found a solution for it yet. For instance I can measure the conductivity but to me it's not straight forward going from Siemens/cm to Ohm over a given distance. I assume the measured conductance is a from a 3D resistor network of unknown value.
Example: Glass tapwater 22 deg C, measured at 264uS/cm. I use a cheap Chinese TDS&EC so this measurement might be off. R= 1/S or R = about 3k8 at 1cm.
What would the resistance be at 2mm? Or at 1mm? How can I find this value?
I'm not looking for a solution to my circuit, there are many easy fixes. I want to understand the conductivity/resistance problem first.