Abstract: A portable apparatus for measuring the electrochemical characteristics of a sample is disclosed. A disposable cartridge, including a plurality of interconnected flow chambers, houses a printed circuit board substrate upon which reference and indicating electrodes are formed. The electrodes are employed in the presence of chemical reagents to aid in the electrochemical determination of a sample undergoing analysis. A thermal sensing element is in close proximity to the electrodes to permit the correction of the measurement for variations in temperature. After a pH value has been determined, the used cartridge can be mechanically ejected thus eliminating user exposure to the blood sample being measured. In this way, the pH of a blood sample can be determined quickly, effectively, inexpensively and with a minimum amount of sample and reagent preparation.

Abstract: Selective plasma vapor etching process for performing operations on a solid body formed of at least two different materials capable of being vapor etched exposed at, at least, one surface of the body, with the body being disposed in a chamber having a partial vacuum therein. A gas plasma is created within the chamber to produce active species of atoms and molecules so that these species come into contact with the surface of the body to chemically react at least one of the materials with active species from the gas plasma to form a gas-non-gaseous chemical reaction by controlling the concentration and reaction kinetics of specific species, and by controlling the activation energy of the etching reactions to produce a difference in rates between the materials so that the etching is more selective to one material over the other. The species is also controlled by the frequency of the electromagnetic energy.