Gas mixing device and gas analyzer making use of the same

An apparatus for analyzing a specimen fluid with respect to specific gas components, comprising:

• a substrate having a plurality of grooves formed thereon by etching including a plurality of inlet grooves and at least one outlet groove, each of said inlet grooves being branched into a plurality of gas passage grooves, and each of said at least one outlet groove being connected with at least two of said inlet grooves through said gas passages grooves;
• a plate having a flat smooth surface, a plurality of inlet ports each communicating with a respective one of said inlet grooves and through each of which a gas to be mixed is introduced from respective gas sources, and at least one outlet port which is to be communicated with a respective said at least one outlet groove and through which a gas mixture is discharged, said plate being bonded at said flat smooth surface to said substrate to define therebetween flow resistance passages constituted by said gas passage grooves, whereby the gases to be mixed together are introduced from said inlet ports into said at least one outlet groove and are mixed into the gas mixture;
• said gas passage grooves having predetermined dimensions of cross-section and length so that gas introduced from said inlet ports are mixed together at a predetermined mixing ratio in said at least one outlet groove for delivery to a respective said outlet port when each gas introduced is maintained a at the same pressure as the pressure of the other gases introduced to said inlet ports;
• at least one reservoir containing a liquid through which the mixture gas from each said outlet groove is bubbled;
• a measuring unit having at least one gas measuring electrode;
• and
• selective communication means for selectively providing communication between said reservoir and said measuring unit.