Abstract: A method is disclosed for calibrating transducers for determining gas concentrations, in particular for the transcutaneous measurement of blood gases. In the method, the testing chamber is exposed on its measuring surface, through an overlay, to a known gas concentration. The method provides for a simpler application of the calibration medium to the measuring surface of the transducer, such that an overlay provided with substances required for furnishing the known gas concentration is applied directly onto the measuring surface of the testing chamber, covering it. An overlay is also disclosed and is embodied as a paper strip having two impregnated zones, separated from one another by an intermediate piece provided with a coating.

Abstract: A measuring device for facilitating the electro-chemical measurement of a substance such as a gas comprises a holder ring which has an opening therethrough with an inwardly extending annular resilient sealing lip extending into the opening and an end face with an inner annular projecting portion defining a fitting strip and an outer annular projecting portion spaced radially outwardly from the inner annular portion. A membrane is engaged over the opening and the inner annular projecting portion and its periphery rests in a space between the inner and outer projecting portions. A tightening ring is engaged with the hole of the ring and it includes an end face with an annular groove which is positionable over the inner annular projection of the holder ring. The tightening ring includes an inner annular counter ring part engageable over the membrane and against the sealing lip of the holder ring.