A new silicon capacitive pressure sensor with center clamped diaphragm is presented. The sensor has a silicon-glass structure and is fabricated by batch-fabrication processes. Since deformed diaphragm has a doughnut-shape, parallel-like displacement is realized and therefore better linearity of 0.7% which is half of the conventional flat diaphragm sensor is obtained. It is clarified both analytically and experimentally that the capacitive pressure sensor with center clamped diaphragm is advantageous in terms of linearity.

An ink-jet head using a buckling diaphragm microactuator is described. The microactuator is composed of a silicon substrate, silicon dioxide insulator, nickel heater layer and electro-plated nickel diaphragm. All the edges of the diaphragm are fixed on the substrate and a narrow gap is formed between the diaphragm and the substrate. A nozzle plate is connected to the actuator by an adhesive spacer to get the ink-jet head. An ink chamber is formed by the surfaces of the diaphragm, the nozzle plate, and the side wall of the spacer. When the diaphragm is heated, thermally induced compressive stress causes the diaphragm to buckle rapidly and the diaphragm simultaneously deflects toward the nozzle plate. The deflection raises the pressure in the ink chamber and an ink droplet is then ejected through the nozzle. The head design was carried out using mechanical analysis of a buckling model, and heat transfer simulation. The diaphragm made from nickel is 300 µm diameter and 2 µm-thick. The narrow gap is 0.4 µm. The cathode current density in nickel sulphamate solution used for nickel electro-plating of the diaphragm was 20 mA/cm2. An ink droplet has been ejected with a velocity of 8 m/s while the ink-jet head is operated by heating the diaphragm with a current of 510 mA at 16.6 V for 10 µs at 1.8 kHz.

A 3-dimensional specific thickness profile was fabricated on a thin glass diaphragm lens to reduce aberration at short focal distances for greater dynamic focusing. The deformation of the diaphragm was calculated by stress analysis utilizing the Finite Element Method (FEM). Geometric non linearity is considered in the FEM analysis. The glass diaphragm is 10 mm in diameter and the average thickness is 11 µm. To obtain both a curved shape and an optical surface on the glass diaphragm, the 3-dimensional precision grinding technique was utilized. The processed shape matches the designed one with less than 0.3 µm deviation, and the average surface roughness is 0.005 µm. Optical characteristics of the dynamic focusing lens having a specific thickness profile, were measured by Modulation Transfer Function (MTF) measurement equipment. At a focal distance of 250 mm, the specific thickness diaphragm lens resolution is 10 cycles/mm, whereas, the uniform thickness diaphragm is 4 cycles/mm. Even at other focal distances, the specific thickness diaphragm shows superior optical characteristics in comparison with those of the uniform thickness diaphragm. The 3-dimensional profile diaphragm resolution is 2.5 times finer at a focal distance of 250 mm, thus, being capable of displacement control for variable optic devices. This was achieved by employing semiconductor processing methods in conjunction with precision grinding techniques which are necessary for fabricating micro structures.