Patent ID: 7466146
Filing Date: 2008-12-16
Classification: G01N

Abstract:
1. An apparatus comprising: a first electrode; a second electrode located at a distance from the first electrode, the second electrode forming a capacitive element with the first electrode, wherein a gap is present between the first and second electrodes, wherein each of the first electrode and second electrode partially surrounds a member subject to accumulation of frozen material, such that the gap is formed between edges of the first and second electrodes along lateral sides of the member; an electric field sensor having an electrode terminal coupled to the first electrode and providing an electric field output value representative of an amount of frozen material located in the gap between the first and second electrodes; a first insulating layer around the member, between the member and the first electrode and between the member and the second electrode; and a conductive layer around the member, between the member and the first insulator, wherein a shield output of the electric field sensor is coupled to the conductive layer.