Importance

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Abstract

A transcutaneous gas sensor for application to the body surface of a patient is provided. The sensor includes a sensing electrode having an exposed surface region which, in use, is applied to the body surface of the patient with an electrolyte layer between the electrode and the patient's body. Gas which has diffused through the patient's body from his blood to the body surface results in an electrochemical reaction taking place at the exposed surface region of the electrode. This exposed surface region can consist of an individual surface area, or several such surface areas. In one embodiment, the surface area or areas are arranged and are of a configuration such as to have associated therewith an imaginary envelope of greater area than the total area occupied by the individual surface area or areas; with such an arrangement, the surface area or areas have the same or similar widths. In a second embodiment, the or each exposed surface area(s) of the electrode has a sufficiently small width dimension and is shaped and arranged so that the depletion zone set up in the electrolyte layer when the sensor is in use is confined to a depth not exceeding about 1 mm. The flow of gas from the patient's blood to his body surface can be encouraged by local heating of the area under investigation. Detection of the current flowing through the electrode as a result of the electrochemical reaction in the electrolyte layer provides a measure of the gas partial pressure in the patient's blood.

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First Claim