CORRECTION ELECTRODE FOR MEASURING PH AND PH MEASURING METHOD

摘要

PURPOSE:To enable exact pH measurement in the light, by combining a pH measuring electrode obtd. by forming a Ta2O5 film on an Si base, with a correction electrode obtd. by forming a Ta2O5 film on an Si base and coating said film with a transparent insulating film. CONSTITUTION:A Ta2O5 film 3 is formed on a P type silicon base 2, on the film 2 a transparent electrode 4 of In2O3-SnO2 or the like is formed, and this is coated with a transparent insulating and water-proof film 5 of polyethylene or the like, and further, an electrode 8 made of Ni or the like is formed on the reverse side of the base 2 to obtain a pH measuring correction electrode 22. This electrode 22 and a pH measuring electrode 21 obtd. by forming a Ta2O5 film 9 on the surface of a base 10, with an electrode 12 on the reverse side, and a contrast electrode 17 are installed in a pH measuring cell 15. A correct pH value can be obtained by eliminating a photovoltaic effect generated on the electrode 21 in the light with a photovoltaic effect generated on the electrode 22 using a differential amplifier 20.