CHEMICAL MICROSENSOR SYSTEMS FOR MEDICAL APPLICATIONS IN CATHETERS

For the analysis of chemical parameters in human blood, miniaturised s ensors have been developed and implemented in common catheter systems. Based on the principle of amperometric sensors, enzyme chips for lact ate and glucose determination have been constructed by depositing a th in-film noble metal electrode and a reference electrode at one side of the silicon chips. The enzymes are entrapped into poly-urethane films which are directly attached to the chip surface and optimised by chem ical surface modification. The potentiometric sensors have silicon mic romachined grooves containing ion-selective ionophores in modified pol y(vinyl chloride) (PVC) and electrodes located on both sides of the si licon chip. By means of an intelligent analyte management system the e xposure time of the sensors to serum or blood was reduced to about one min/hour. The sensors are conditioned and calibrated immediately befo re each blood measurement. The analyte and calibrant handling and the signal treatment are controlled by a microprocessor. The sensors assem bled in the catheter tip respond reproducibly and accurately to the re spective analytes in human serum for more than 70 h.