Fet sensor with specially configured gate electrode for the highly sensitive detection of analytes

A sensor for the detection of an analyte, the sensor comprising

• a substrate forming a first plate of a first capacitor,
• a source contact region on the substrate,
• a drain contact region on the substrate,
• a gate oxide of a transistor on the substrate between the source contact region and the drain contact region and forming an insulator of the first capacitor,
• a gate electrode having inner and outer faces, the inner face being smaller than the outer face and forming a second plate of the first capacitor, the outer face forming a first plate of a second capacitor connected in series with the first capacitor, the gate-electrode inner face contacting the gate oxide over a predetermined inner contact area;
• an electrically insulating detection electrode forming an insulator of the second capacitor and having inner and outer faces, the detection-electrode inner face contacting the gate-electrode outer face;
• an immobilized receptor fixed on the detection-electrode outer face for detecting a presence of the analyte and forming a second plate of the second capacitor;
• and
• an insulator body potting all of the source contact region, drain contact region, gate electrode, and gate oxide and the detection electrode except at the detection-electrode outer face carrying the immobilized receptor to form a series circuit of the two capacitors and increase a charge density toward the transistor to enhance a detection sensitivity of the transistor.