Method of making an electrochemical sensing cell
AssigneeCordis Europa N.V.
InventorsGerrit Koning, Piet Bergveld
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Abstract
An in vivo electrochemical monitoring device is formed by a catheter-like member which terminates in a closed end having a wall with a fixed opening to admit fluid to be tested, such as blood in an artery. An electrochemical sensor, such as an ISFET device for monitoring the concentration of a particular ion in blood, is mounted inside the tube at a fixed location below the opening preferably a larger sensing chamber. An infusion channel in the tube is arranged to flood the sensor with a fluid of known chemical properties so that the sensor output can be calibrated. Under pressure the calibration fluid expels the test fluid out of the tube or chamber via the fixed opening. A method of constructing a suitable chamber on an ISFET wafer is also disclosed.
Claims5
A method of making a sensing cell for a chemically sensitive probe for measuring the properties of biological fluids in vivo, comprising the steps of
- producing a wafer comprising an ISFET with spaced source and drain regions spanned by an ion-sensitive gate portion,
- covering said source and drain regions and gate portion of said ISFET with a temporary first layer of soluble material,
- covering said temporary first layer with a second layer of relatively insoluble material,
- defining an opening in said second layer directly above said gate region, and
- removing said temporary first layer which covers the source and drain regions and the gate portion by introducing a solvent through said opening to dissolve said first layer, thus forming a sensing chamber encompassing the source and drain regions as well as the gate portion of said ISFET.
Dependencies are inferred from the claim text.