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Level-Sensing Scheme for Electrolytic Solutions

IP.com Disclosure Number: IPCOM000100590D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Kanazawa, K: AUTHOR

Abstract

The palladium wires are shown immersed in an electrolytic solution to serve as a level-sensing monitor. The AC output from the associated electronic circuitry has an amplitude which is linearly related to the level of the electrolyte.

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Level-Sensing Scheme for Electrolytic Solutions

       The palladium wires are shown immersed in an electrolytic
solution to serve as a level-sensing monitor.  The AC output from the
associated electronic circuitry has an amplitude which is linearly
related to the level of the electrolyte.

      When an inert metal electrode is inserted into an
electrolytically conducting solution and is biased at some potential
relative to the solution, a distributed double layer of charge is
formed at the metal- solution interface. This charge storage regime
forms an effective double layer capacitance.  By applying a small
perturbing sinusoidal voltage in addition to the biasing potential,
the charge stored in the double layer varies accordingly, and the
resulting current is a measure of the differential capacitance.  This
differential capacitance is large and is easily measured, having
values in the order of tens of microfarads per square centimeter.
The value of the differential capacitance is proportional to the area
of the metal in contact with the liquid.

      An AC voltage applied to the two electrodes shown in the figure
(the CONTROL electrode and the SENSE electrode) develops a cyclically
varying double layer region surrounding each wire.  The width of
these regions are typically less than a hundred angstroms, insuring
that the capacitance is independent of the relative position between
the electrodes.  This is in marked contrast to certain other
level-sensing...