A sensor includes a substrate, an oxide layer, a membrane, an electrode, and a trench. The oxide layer is disposed on the substrate. The membrane is positioned on the oxide layer. The membrane with the oxide layer and the substrate forms an enclosed cavity therein. The membrane comprises a rigid portion and a deformable portion wherein the deformable portion of the membrane deforms responsive to stimuli. The oxide layer forms side walls of the cavity. The electrode is positioned on the substrate and within the cavity. The trench is formed in the oxide layer, and wherein the trench is covered with barrier material.