Patent ID: 6249130
Filing Date: 2001-06-19
Classification: G01D,G01N,H03K

Abstract:
A capacitive sensor element, comprising:(a) a dielectric substrate having a planar configuration;(b) a pair of sensing electrodes arranged on one surface of said substrate in spaced relation; and(c) shielding electrode means being grounded and arranged between and parallel to said pair of sensing electrodes for interrupting at least a portion of the electric field lines generated from one of said sensing electrodes when an electric current is supplied thereto, thereby to direct the electric field lines in a given direction while preventing interference from the dielectric substrate, said shielding electrode means comprising(1) a first shield electrode arranged on a surface of said substrate opposite said one surface, said first shield electrode being parallel to said sensing electrodes and limiting a measuring field defined by said electric field lines to 180.degree. on said one surface of said dielectric substrate; and(2) a second shield electrode arranged on said one surface of said substrate between and co-planar with said sensing electrodes in spaced parallel relation to prevent the dense electric field very near the sensor element from severely dominating a measurement, whereby when a substance being measured is proximate the sensor element, changes in the electric field lines are detected as a function of the characteristics of the substance.