A method of fabricating a semiconductor device for sensing biological material includes: forming a field-effect transistor (FET) on a semiconductor substrate that includes a gate; forming a well within a material disposed over the semiconductor substrate, the well having an opening at a first end and a floor at second end, the well further having one or more side walls extending from the floor toward the opening to define an open-ended cavity into which a fluid may be flowed; forming a via extending through the floor such that an end-most surface of the via resides proud of the floor in a direction of the well's opening, the via being electrically coupled to the gate; and forming a sensing layer that at least partially covers the floor and a portion of the via residing proud of the floor, the sensing layer being reactive to exposure to a biological material.