Transcutaneous carbon dioxide measurement electrode assembly

Claim 1

In a transcutaneous carbon dioxide measurement electrode assembly having a central tubular glass electrode having a bottom end, said electrode being composed of a highly insulating material, at said bottom end is positioned a pH responsive glass membrane, said glass membrane having an outer surface for contacting the skin and an inner surface exposed to the interior of the tubular glass electrode, a reference electrode surrounding said glass electrode, a membrane holder, carbon dioxide-permeable polymer membrane bonded to said membrane holder and which is positioned at said bottom end, a skin-heating member which provides a body contacting surface and an aperture through which the CO 2 gas being measured is carried to said glass electrode via said membrane and further includes a heater for heating the body contacting surface and provided with a heat sensitive element controlling said heater to maintain said body at a designated temperature, said heating member supporting the membrane holder in a space between said reference electrode and said skin heater so as to form between the CO 2 -permeable membrane and the outer surface of said glass membrane an electrolyte chamber for an electrolyte solution which contacts the reference electrode, the improvement comprising a conductive layer formed on the inner surface of said glass membrane, a preamplifier disposed within said glass electrode, a short lead wire connected between said conductive layer and the input terminal of said preamplifier, the output terminal of said preamplifier adapted to be connected to an external low output impedance, measuring device, said glass electrode being filled with an insulating solid material.