notsolowki:
im not sure if isolating just the signal wire will do it. the ph senson im using has a series of opamps that do the conversion and send a 0 5v signal to the arduino through the analog port. im afraid since the ph sensors amplifier is powered by a non isolated psu then the ground on the ph probe will still loop?
These are 'signal amplifiers' where the input to output is physically isolated from each other.
These isolated your transducer analog signals from a controller, PLC etc.
These are similar to what an optoisolator does for digital signals.