Prototype miniature blood gas analyser fabricated on a silicon wafer

The fabrication of a miniature blood pH monitoring system formed on a silicon wafer using a pH ISFET and a new type of micro-valve actuator is described. The system samples the blood from the vein, measures its pH and calibrates zero drift of the sensor automatically and periodically. The main body of the system, the micro-cell, is made of a silicon wafer and a Pyrex glass plate processed by IC technology (micro-machining). This cell is significantly smaller, lighter and more portable than presently available blood gas analysers, in particular, the sample volume reduction is a very distinctive feature of it. The total necessary sample volume of the system is about 10 μl.