| 摘要 |
1283158 Gas sensor JOHNS HOPKINS UNIVERSITY 20 May 1970 [20 May 1969] 24523/70 Heading G1N In a sensing device for determing tissue carbon dioxide or oxygen and hence effective alveolar ventilation the gas is directly introduced to a liquid filled cup in which liquid is positioned a gaspermeable membrane-faced ph sensing electrode for determining the concentration of the gas. The ph sensing head 10 includes a ph sensitive glass electrode 38 containing a silver chloride coated silver wire and electrolyte E together with a reference silver chloride coated silver wire electrode 44. The electrode 38 is positioned in a saline buffer solution B in a cavity 26 formed by members 32, 34 and the open end of which is closed by a gas permeable but not liquid permeable membrane 64 backed by a thin disc of bibulous material 62 such as nylon mesh. After insertion of the ph sensing electrode in cavity 26 metal sleeve 18 is press-fitted about cylinder 24 so as to form, when the head 10 is positioned over a prepared skin area 5 of a patient's arm, a cup or well in which water or saline solution C is introduced, the device being held in position by a malleable lead base-plate L strapped around the arm, Fig.1 (not shown). Gas in the tissue of the patient diffuses freely through the skin, through liquid C, membrane 64 and liquid B into cavity 26 where it affects the ph measurement on a meter connected to leads 56, 60. The lead base-plate L acts as a thermal sink to mimimize temperature changes within the sensor. |
