Sensor with conductor and sealing glass

Abstract

An apparatus for use with a patient having a vessel carrying blood to ascertain characteristics of the blood. The apparatus includes a display module and a probe having a distal extremity adapted to be inserted into the vessel of the patient and having a proximal extremity coupled to the display module. The probe includes a sensor in the distal extremity for providing an electrical signal to the display module when the probe is disposed in the blood. The probe can have an antithrombogenic surface treatment for inhibiting the adhesion of blood components to the probe when disposed in the blood.

1 . A probe for use in a patient having a vessel carrying blood to ascertain characteristics of the blood comprising a cannula having proximal and distal extremities, the distal extremity being adapted to be inserted into the vessel of the patient, an electrolyte solution disposed in the cannula, a gas sensor assembly mounted in the distal extremity of the cannula and including an electrode disposed in the electrolyte solution, a conductor extending to the electrode and a sealing glass extending around the conductor, the conductor having a coefficient of thermal expansion and the sealing glass having a coefficient of thermal expansion approximating the coefficient of thermal expansion of the conductor for inhibiting separation of the conductor from the sealing glass and thus inhibiting the electrolyte solution from creeping between the conductor and the sealing glass. 
     
     
         2 . The probe of  claim 1  wherein the conductor has a cleaved extremity to form an active area of the electrode. 
     
     
         3 . The probe of  claim 2  wherein the conductor is made of platinum. 
     
     
         4 . The probe of  claim 1  wherein the gas sensor assembly includes an additional electrode disposed in the electrolyte solution. 
     
     
         5 . A probe for use in a patient having a vessel carrying blood to ascertain characteristics of the blood comprising a cannula adapted to be inserted into the vessel of the patient and having proximal and distal extremities, an electrolyte solution disposed in the distal extremity of the cannula, a gas sensor assembly mounted in the distal extremity of the cannula and disposed in the electrolyte solution, the gas sensor assembly having a tube with a distal portion and a first electrode coiled around the tube and a second electrode carried by the distal portion of the tube, first and second conductors extending from the proximal extremity of the cannula to the gas sensor assembly, the first conductor being coupled to the first electrode and the second conductor extending through the tube and being coupled to the second electrode whereby the tube serves as support for the first electrode and as a conduit for the second conductor. 
     
     
         6 . The probe of  claim 5  wherein the gas sensor assembly includes a sealing glass extending around the second conductor at the distal portion of the tube for forming the second electrode. 
     
     
         7 . The probe of  claim 6  wherein the second conductor has a coefficient of thermal expansion and the sealing glass has a coefficient of thermal expansion approximating the coefficient of thermal expansion of the second conductor for inhibiting separation of the conductor from the sealing glass and thus undesirably permitting the electrolyte solution to creep between the conductor and the sealing glass. 
     
     
         8 . The probe of  claim 5  wherein the second conductor has a distal end portion made of platinum. 
     
     
         9 . The probe of  claim 5  wherein the first electrode is a reference electrode and the second electrode is a carbon dioxide electrode. 
     
     
         10 . The probe of  claim 5  wherein first electrode is a reference electrode and the second electrode is an oxygen electrode. 
     
     
         11 . A probe for use in a patient having a vessel carrying blood to ascertain characteristics of the blood comprising a cannula having proximal and distal extremities, the distal extremity being adapted to be inserted into the vessel of the patient, a flex circuit extending through at least a portion of the cannula, the flex circuit having proximal and distal portions with first and second electrodes formed on the distal portion and first and second conductors extending from the proximal portion to the first and second electrodes, an electrolyte solution disposed in the distal extremity of the cannula in the vicinity of the first and second electrodes. 
     
     
         12 . The probe of  claim 11  wherein the cannula is gas permeable in the vicinity of the first and second electrodes. 
     
     
         13 . The probe of  claim 12  wherein the entire cannula is made of a gas permeable material. 
     
     
         14 . The probe of  claim 13  wherein the gas permeable material is polymethylpentene. 
     
     
         15 . The probe of  claim 11  wherein the flex circuit includes first and second layers of an insulating material, the first and second conductors extending along and between the first and second layers. 
     
     
         16 . The probe of  claim 15  wherein each of the first and second layers has an exposed surface, the first and second electrodes each being a pad formed on one of the exposed surfaces of the first and second layers. 
     
     
         17 . The probe of  claim 11  wherein the flex circuit includes at least one layer of insulating material, first and second contact pads formed on the at least one layer of insulating material at the proximal portion of the flex circuit and coupled respectively to the first and second conductors, the first and second contact pads permitting electrical communication with the flex circuit outside of the patient. 
     
     
         18 . The probe of  claim 17  wherein the distal extremity of the cannula is adapted for slidable travel through an introducer when inserting the cannula into the vessel, the cannula and the flex circuit having a size which permits the introducer to be slid off of the proximal extremity of the cannula and the flex circuit after the distal extremity of the cannula has been inserted into the vessel. 
     
     
         19 . The probe of  claim 11  further comprising adhesive disposed within the cannula for securing the flex circuit within the cannula. 
     
     
         20 . The probe of  claim 19  wherein the cannula is provided with a sealed chamber in which the first and second electrodes are located, the electrolyte solution being disposed in the sealed chamber. 
     
     
         21 . The probe of  claim 20  wherein the cannula is provided with an additional sealed chamber in which third and fourth electrodes are located, the electrolyte solution being disposed in the additional sealed chamber.