A microelectronic sensor for non-invasive monitoring of glucose levels in blood is based on the combination of an open-gate pseudo-conductive high-electron mobility transistor and a Vivaldi antenna installed in the open gate area of the transistor. The sensor is capable of sensing sub-THz radiation produced by a body of a user, and comprises a heterojunction structure made of the layers of GaN/AlGaN single- or poly-crystalline semiconductor materials stacked alternately and a conducting channel comprising a two-dimensional electron gas (2DEG) or a two-dimensional hole gas (2DHG) formed at the interface between the GaN/AlGaN layers. The highest sensitivity of the sensor is achieved when the thickness of the top recessed layer (GaN or AlGaN) in the open gate area between the source and drain contacts is 5-9 nm and the surface roughness of this top layer is about 0.2 nm or less.
