Streaming potentials in conductive and nonconductive tubing

The feasibility of using streaming potentials measured in blood flow for diagnostic purposes (electroarteriograms) was studied by flowing electrolyte solutions in both nonconductive and conductive tubings as model systems. Streaming potentials measured for 10 to the minus 4 power M and 10 to the minus 5 power M sodium chloride solutions in nonconductive polyethylene tubing obeyed the published theoretical relationships between potential and velocity. Under the same conditions, tubes constructed from conductive Nafion and a cationic exchange material which possessed the same ion-exchange group did not exhibit measurable streaming potentials while an apparent streaming potential was observed with an anionic exchange tubing. Electroarteriogram signals may not represent streaming potentials since blood electrolyte concentrations yield a conductivity that may be too high to cause a measurable effect.