Pressed-disk electrode with low contact potential monitors physiological processes. It consists of silver and silver chloride combined with bentonitic clay. The clay affords a surface that permits use over extended periods without contact deterioration

Day, J. L.

Mosier, B.

English

NASA Technical Reports Server

Finished Electrode 
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Wire 
October 1965
	 Brief 65-10320 
NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Rugged Pressed Disk Electrode Has Low Contact Potential 
30.000 psi
Silver-Silver
Chloride-Clay Mixture 
The problem: To produce a biopotential electrode 
for monitoring physiological processes that exhibits 
low contact potential and resistance. The device must 
be sufficiently rugged to have long operating life even 
when used on a subject doing hard physical work. 
The solution: A pressed-disk electrode of silver 
and silver chloride combined with bentonitic clay has 
a very low contact potential. The bentonitic clay af-
fords a surface that permits use over extended periods 
without contact deterioration. 
How it's done: The electrodes are prepared by 
combining 90 parts by weight of powdered silver with 
10 parts of silver chloride. This mixture is then com-
bined with bentonitic clay in a ratio of 95 parts Ag-
AgC 1 to 5 parts clay. The mixture is placed in a spe-
cially constructed die in which the electrode lead wire 
has been properly positioned. The die is placed in a 
vacuum chamber and the mixture is subjected to a 
compressive force of 30,000 psi for a period of 30 to 
60 seconds. The vacuum removes air and moisture 
that would react with the polymers to form oxidized 
compounds in the form of hard gels that adversely af-
fect electrode potentials. 
Notes: 
1. The disks produced by this method are uniformly 
porous and permeable; they exhibit contact poten-
tials of about —5.7 microvolts and are impervious 
to bacteria or protein molecules.
(continued overleaf) 
Now
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use bf the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19650000318 2020-03-11T17:21:25+00:00Z
2. A related innovation is described in NASA Tech 
Brief 64-10025, May 1964. Inquiries may also be 
directed to: 
Technology Utilization Officer 
Manned Spacecraft Center 
P.O. Box 1537 
Houston, Texas, 77001 
Reference: B65-10320
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about ob-
taining rights for its commercial use may be made to 
NASA, Code AGP, Washington, D.C., 20546. 
Source: J. L. Day, NASA and 
Institute of Research and Instrumentation 
under contract to Manned Spacecraft Center 
(MSC-158) 
Brief 65-10320	 Categories 01, 03, 04


Rugged pressed disk electrode has low contact potential

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