ULTRASONICALLY CLEANED ELECTRODE 



R. H. vanHAAGEN and E. E. AAGAARD 



Oceanic Instruments, Inc. 



Houghton, Washington 



ABSTRACT 



Electrodes, such as used in pH, Redox dis- 

 solved oxygen and electrical conductivity measure- 

 ments of solutions are frequently subject to 

 fouling when used in biological laboratories or 

 marine environments . A probe electrode has been 

 devised which can be subjected to high intensity 

 ultrasonic vibrations to eliminate the accumula- 

 tion of fouling materials on the electrode sur- 

 face. The electrode is driven by a tube of a 

 magnetostrictive material rigidly attached to 

 the electrode. An alternating magnetic field is 

 supplied by a solenoid wound around the probe. 

 A compact transistorized power supply has been 

 constructed to energize the solenoid. The ultra- 

 sonic electrode was originally developed for 

 Redox measurements . Cells for electrical con- 

 ductivity measurements in two and three electrode 

 configurations are currently under test and 

 results will be described. 



INTRODUCTION AND BACKGROUND 



All electrode reactions are either oxidation 

 reactions or reduction reactions and these are 

 responsible for typical marine pitting and gal- 

 vanic corrosion which are so costly to the 

 industrialized parts of the world. Oxidation is 

 de-electronation and reduction is electronation, 

 to use the terminology of Professor E. C. Frank- 

 lin of Stanford University. Corrosion protec- 

 tion is therefore obtained by cancelling these 

 effects against each other with sacrificial 

 materials or by supplying a counter electron cur- 

 rent. These reactions are further useful since 

 titration end-points may be obtained for certain 

 reactions by measurement of the oxidation- 

 reduction potential. 2 Servo-electric control 

 of a reaction can also be affected by this mea- 

 surement but the metallic electrode must be in 

 electrical contact with the solution in which 

 the reaction is taking place. 



The susceptibility to biological fouling of 

 electrodes in aqueous solutions is well known 

 and several recent ISA papers describe efforts 

 directed toward relieving this difficulty in 

 measurement of electrical conductivity of 

 solutions. 3 !*>5> ° 



A single metal electrode was recently required 

 to be used for control feedback measurement in a 



solution of human body wastes in which photo- 

 synthesizing algae would flourish to provide 

 oxygen and protein food for mock space flight. 

 The prototype system (Fig. l) involved a large 

 resin kettle with the electrode inserted through 

 one aork hole. 



Fig. 1. Prototype scrubbed electrode system. 



Superior numbers refer to similarly numbered references at the end of this paper. 



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