Transcutaneous sensor insertion set

DETAILED DESCRIPTION In accordance with the invention, a subcutaneous insertion set is provided for placing a flexible sensor such as a thin film electrochemical sensor at a selected site within the body of a patient.
The insertion set comprises a slotted insertion needle extending through a mounting base adapted for seated mounting onto the patient's skin.
A flexible thin film sensor includes a proximal segment carried by the mounting base, and a distal segment protruding from the mounting base and having one or more sensor electrodes thereon.
The distal segment of the sensor is carried within a protective cannula which extends from the mounting base with a portion of the cannula being slidably received within the insertion needle.
One or more windows formed in the cannula are positioned in general alignment with the sensor electrodes on the sensor distal segment.
When the mounting base is pressed onto the patient's skin, the insertion needle pierces the skin to transcutaneously place the catheter with the sensor distal segment therein.
The insertion needle can be withdrawn from the mounting base, leaving the catheter and sensor distal segment within the patient, with the sensors electrodes thereon exposed through the window or windows for direct contact with to patient fluid at the selected position within the patient, such as a subcutaneous, intravascular, intramuscular, or intravenous site.
Conductive contacts on the sensor proximal end can be electrically connected to a suitable monitor device so that appropriate blood chemistry readings can be taken.
In the preferred form, the insertion needle has a cross-sectional shape which is somewhat greater than 180.
degree.
in arcuate cross section.
This part-circle needle construction protrudes downwardly from the mounting base of the insertion set, and terminates in a sharp tip for piercing the patient's skin.
A first portion of the protective cannula has a cross sectional shape for nested reception within the insertion needle, to extend from the mounting base to a distal end which terminates at least slightly before the needle tip