In one embodiment, a chemical sensor is described. The chemical sensor includes a chemically-sensitive field effect transistor including a floating gate conductor having an upper surface, a first opening extending through a first material and through a portion of a second material located on the first material and a second opening extending from the bottom of the first opening to the top of a liner layer located on the upper surface of the floating gate conductor.

A field effect transistor, FET, gas sensor device (100) arranged to sense gas, and a method of sensing gas by a FET gas sensor device, are provided. The FET gas sensor device comprises at least one gate (110a, 110b), a source (120), a drain (130), and a semiconductor channel (140). The semiconductor channel and the gate(s) form a FET channel-gate coupling (150) by which an applied gate potential is arranged to control a current flowing through the semiconductor channel. The FET gas sensor device further comprises space(s) (200) arranged between the gate(s) and the semiconductor channel and configured to receive gas, whereby received gas is arranged to influence electrical property(ies) of the FET channel-gate coupling, and wherein the FET gas sensor device is arranged to sense gas based on the influenced electrical property(ies) of the FET channel-gate coupling.

A electronic device and a fabrication method is provided. The electronic device having a first electrode and a second electrode. A nano-gap is formed between first and second electrode. The first electrode, the second electrode and the gap may be located in the same layer of the device. A two-dimensional layer of graphene may cover the gap.