The collapse voltage of micromachined capacitive ultrasonic transducers (CMUT) depends on the size, thickness, type, and position of the metal electrode within the membrane. This paper reports the result of a finite element study of this effect. The program (ANSYS 5.7) is used to model a circular membrane on top of a Si substrate covered by a Si3N4 insulation layer. We find that the collapse vo...

This paper proposes a Micro-electro-mechanical (MEMS) capacitive pressure sensor that relies on the movable electrode displaced like a flat plate equal to the maximum center deflection of diaphragm. The diaphragm, movable electrode and mechanical coupling are made of polysilicon, gold and Si3N4, respectively. The fixed electrode is gold and the substrate is Pyrex glass. This proposed method inc...

Theoretical limits for the capacitance density of lateral flux and quasi-fractal capacitors are calculated. These limits are used to investigate the efficiency of various capacitive structures such as lateral flux and quasi-fractal structures. This study leads to two new capacitor structures with high lateralfield efficiency. Simulation and experimental results demonstrate higher capacity and s...

Theoretical limits for the capacitance density of lateral flux and quasi-fractal capacitors are calculated. These limits are used to investigate the efficiency of various capacitive structures such as lateral flux and quasi-fractal structures. This study leads to two new capacitor structures with high lateralfield efficiency. Simulation and experimental results demonstrate higher capacity and s...

We have designed and fabricated the first single-wafer proportional micro control valve with built-in capacitive displacement sensing. The displacement sensor can facilitate high-speed active proportional control of gas flow through the valve. This is an essential requirement for non-invasive blood pressure waveform monitoring based on following the arterial pressure with a counter pressure. We...

The effect of flexibility and initial curvature of moving plates in parallel-plate MEMS capacitors are investigated. A parallel-plate-based MEMS tunable capacitor with extended tunability and linear capacitance-voltage (C-V) response is introduced. The design combines the flexibility and curvature of the electrode with an array of mechanical stoppers to increase the overall stiffness of the dev...

A capacitive angular position sensor capable of covering 360" is presented. It is made up of four quadrants, each of which consists of a parallel plate capacitor whose higher potential plate (HPP) has a specific shape. A grounded semi-circular plate, whose angular position is measured, moves between these capacitors. When these capacitors are supplied with sinusoidal voltages of mutually shifte...

1. Abstract A well designed capacitive micro-machined switch requires small electrostatic pull-in force to easy switch-on and high natural frequencies to fast switch-off. Since the change of geometrical parameters of the bridge (moving part of the switch) affects contrary to one of these aspects, one could search for a shape of the bridge to obtain optimum functioning. The paper deals with desi...

We show how to achieve large-amplitude oscillation and good frequency stability in a nonlinear NEMS oscillator by using a softening nonlinearity to locally balance the hardening behaviour of the Duffing nonlinearity for a given motion amplitude. The case when the softening behaviour is obtained via electrostatic biasing is theoretically investigated, under parallel-plate assumptions, for a full...