Abstract: An acoustic transducer includes a perforated member; a movable diaphragm spaced from the perforated member; spring means interconnecting the diaphragm and the perforated member for movably supporting the diaphragm relative to the perforated member; a pressure equalization slot for controlling the flow of fluid through the diaphragm, the slot equalizing the pressure on opposite sides of the diaphragm for defining the low frequency response; and means for applying an electric field across the perforated member and the diaphragm for producing an output signal representative of the variation in capacitance induced by the variation of the space between the perforated member and the diaphragm in response to an incident acoustic signal.

Abstract: A microfabricated tuning fork rate sensitive structure and drive electronics in which vibrational forces are communicated through a set of meshing drive and driven finger electrodes associated with each of two vibrating elements. The vibrating elements are supported in a rotatable assembly between first and second support electrodes which are in turn suspended by flexures for rotation about an axis passing through the flexures and through a point midway between the vibrating elements. Additional masses are formed onto the vibrating elements to improve overall sensor sensitivity. Sense electrodes for detecting capacitive changes between the support electrodes and the sense electrodes are positioned at each end of the support electrodes. Drive electronics are connected between the driven fingers of the vibrating elements and the drive electrode fingers which mesh with them to cause vibration. Excitation is provided between the support electrodes and the sense electrodes.

Abstract: A bridge electrode structure and method of fabrication thereof is provided that is adapted to provide electrically isolated metal bridges over the active portions of a monolithic micromechanical transducer. The bridge electrode of the invention is also adapted to operate in facing relationship with one or more buried electrodes, providing top-to-bottom symmetry for balanced application of forces, or motion detection when used in conjunction with transducer elements. The transducer, typically a gyroscope or an accelerometer, includes a semiconductor substrate and active elements etched out of the substrate, the active elements including flexure-supported transducer plates. The bridge electrodes are anchored at opposing points on the substrate's surface to metal layers used to facilitate their electro-forming. The central portions of the bridge are electroplated over an insulating spacer, such as a photoresist layer.

Abstract: A symmetrical micromechanical gyroscope includes an inertial mass symmetrically supported about both drive and sense axes, for detecting rotational movement about an input axis. Two pairs of flexures attached to diametrically opposed sides of the inertial mass support the mass within a gyroscope support frame. Each of the flexures are oriented at generally a 45.degree. angle from both the drive and the sense axes. In response to an applied drive signal, the inertial mass is induced to vibrate about a drive axis which is co-planar with and orthogonal to the sense axis. Both pair of flexures participate equally during rotation of the mass.

Abstract: An acoustic transducer includes a perforated capacitor plate; a movable capacitor plate spaced from the perforated plate; springs for movably supporting the movable capacitor plate relative to the perforated plate; and a support structure for supporting the perforated and movable plates, where the movable plate is interconnected to the support structure by the springs and where the plates, springs and support structure form a unified, monolithic structure. The movable plate, springs and support structure are made from a silicon wafer. The transducer also includes a dielectric fluid in the space between the plates; and equipment for applying an electric field across the plates for producing an output signal representative of the variation in capacitance induced by the variation in space between the plates in response to an acoustic signal.

Abstract: A process is disclosed for fabricating a free-standing thin or thick film structure. One embodiment of the process includes the steps of providing a substrate of a first refractory material, forming a layer of carbon on the substrate, and depositing a film of a second refractory material on top of the layer of carbon. This sandwich structure is heated in an oxidizing ambient to cause the oxidation of the carbon layer leaving the second refractory material as a free-standing film.