GB959074A - Electric relay operating by electrocapillarity - Google Patents

Abstract

959,074. Mercury switches. COMMISSARIAT A L'ENERGIE ATOMIQUE. June 25, 1962 [July 3, 1961], No. 24345/62. Heading H2B. A closed vessel 1 has two flexible diaphragms 4, 4a dividing it into two chambers 2 and 3. Chamber 2 contains an electrolyte such as sulphuric acid or sodium hydroxide, and chamber 3 contains an insulating liquid such as hexane. Electrodes 5 and 5a are provided in chamber 2 and an insulating partition 6 of glass or plastic material, for example, is situated between them. The partition 6 contains a large number of capillary passages 7 each having a central widened portion containing a bead 8 of mercury. The part of vessel 1 forming the chamber 3 has two enlarged portions 9 and 9a with a constriction 12 therebetween. Pairs of contacts 10 and 10a are provided in portions 9 and 9a, respectively, and a bead of mercury 11 fills one of the portions, interconnecting the contacts therein. It is stated that a potential of the order of 1 volt applied between electrodes 5 and 5a will cause the mercury beads 8 to move towards one electrode, dependent upon the polarity and the nature of the electrolyte, and thus exert a differential pressure (via the diaphragms 4 and 4a and the liquid in chamber 3) upon the mercury bead 11, causing it to move into the other enlarged portion and bridge the contacts therein. Reversal of the potential causes the bead 11 to move back again. Deformable parts 13 in the wall of the vessel 1 allow for thermal expansion of the fluids.