In one embodiment, a method and apparatus for processing an audio signal are provided. A camshaft shaft is journaled for rotation within the engine body. A portion of the isolation barrier dielectric layer is removed to form an undercut region within the gate region and a charge trapping material is deposited within the undercut region. The plug has inner and outer surfaces and a contour side wall. In certain embodiments the organometallic material comprises a ferrocene polymer. At least one of the side walls can be opened and closed.