Field effect sensor - determines the concn. of anion 'X' in a soln. and comprises silicium substrate with electrically non-conductive coating on one side.

摘要

The sensor comprises a silicium substrate (1), an insulator layer (2) of silicium dioxide and silicium nitride, an adhesive layer (3) of chrome, and a sensitive silver iodide layer (4), and is integrated in a vessel (5). The vessel is filled with a watery measurement soln. (6), which contains iodide anions in a concn. between 10-6 and 10-1 Mol/1. In the measurement soln. immerses a reference electrode (7). The potentials are measured via the reference electrode (7) and a contact electrode (8) on the silicium substrate (1). The chrome layer (3) has a thickness between 10 and 500 nm. The difficulty soluble silver cpd. is applied on the chrome to a thickness of 10 to 5000nm. The electrically non-conductive layer is provided with a metallic coating, and the difficulty soluble silver cpd. with the general formula AgX is applied by evapn. under reduced pressure on the metallic layer. USE - To measure the concn. of anion 'X' in a soln.