Patent ID: 6586950
Filing Date: 2003-07-01
Classification: G01R

Abstract:
A capacitive sensing system for testing a material sample, comprising:a sensor, comprising a body, two electrical conductors, and an electrically conductive shield, with a chamber disposed between said two electrical conductors for admitting said material sample, said chamber electrically insulated to inhibit electrical conduction between said two electrical conductors through said material sample, said chamber and said two electrical conductors disposed inside said electrically conductive shield; and a circuit, comprising: an oscillator circuit coupled to said two electrical conductors for producing a measurement signal having a frequency responsive to a capacitance defined by said two electrical conductors and a dielectric region between said two electrical conductors comprising said material sample in said chamber; an indicator circuit for displaying a measurement indication in response to said frequency of said measurement signal, said indicator circuit reversing a polarity of said measurement signal at predetermined intervals with respect to a predetermined electrical potential.