Apparatus and method for measuring the concentration of components in fluids

An improved field effect transistor of the type having a semiconductor substrate with a doping polarity, at least two diffusion regions located at a surface of said substrate;

• an electrically insulating layer overlying the surface of said substrate between said diffusion regions;
• an electrically conductive layer overlying the surface of said insulating layer between said diffusion regions;
• means for imposing an electrical charge on said electrically conductive layer;
• and means for imposing an electrical potential between said diffusion regions, wherein the improvement comprises:
• a bridge member mounted to the insulating layer and extending over the electrically conductive layer so as to form a gap between said bridge member and said electrically conductive layer, said bridge member allowing for passage of fluid therethrough and being capable of having an electrical charge imposed upon it;
• and
• means for imposing an electrical charge on the bridge member.

A method for detecting a concentration of components in a fluid, comprising the steps of:

• doping a semiconductor substrate so as to impart a doping polarity to the substrate;
• forming at least two diffusion regions at the surface of the substrate;
• insulating the surface of the substrate between the diffusion regions by placing an electrical insulating layer adjacent the substrate;
• mounting a bridge member to the insulating layer so as to form a gap between the bridge member and the insulating layer;
• imposing an electrical charge on the bridge member;
• imposing an electrical potential between the diffusion regions;
• introducing a fluid through the bridge member and into the gap between the bridge member and the insulating layer;
• and
• detecting current flow between the diffusion regions.