Thermoelastic damping (TED) in a circular micro-plate resonator subjected to an electrostatic pressure is studied. The coupled thermo-elastic equations of a capacitive circular micro plate are derived considering hyperbolic heat conduction model and solved by applying Galerkin discretization method. Applying complex-frequency approach to the coupled thermo-elastic equations, TED is obtained for...

Differing from the structure of traditional parallel plate capacitive sensor a semi cylindrical capacitive sensor has been introduced in this present work to measure the soil moisture conveniently. Here, the numerical analysis method to evaluate the capacitance from the semi-cylindrical capacitive sensor is analyzed and discussed. The changes of capacitance with the variation of soil moisture o...

Detection of motion with parallel plate capacitors is commonly used in MEMS; small amplitude of motion is typically assumed. In this paper, we derive precise and constructive equations for the case of parallel plate capacitive detection of arbitrary amplitude of motion. These equations are solved in closed form without using a small displacement assumption. A precise relation between the amplit...

A new metal mesh coupler that makes use of a tunneling effect of evanescent waves between a metal mesh and a dielectric plate, has been proposed as a quasi-optical component for millimeter and submillimeter wavelengths. Theoretical calculation and experimental measurement performed from 40 GHz to 60 GHz show that the transmittance of the coupler can be changed more than 50 % for the variation o...

Using a patterned, grating-like plate to control the electromagnetic near field, we demonstrate focusing well beyond the diffraction limit at approximately 1 gigahertz. The near-field plate consists of only capacitive elements and focuses microwaves emanating from a cylindrical source to a spot of size approximately lambda/20 (half-power beamwidth), where lambda is the free-space wavelength. Th...

Capacitive sensing at long ranges (10x the plate diameter) for long-term environmental monitoring can be limited by slow but significant measurement drifts from charge induction, which exceed small capacitance variations of interest, below 0.01%. This paper proposes a slope modulation differential method single-plate capacitive sensors operating in loading mode that effectively rejects noise qu...

In this paper, nonlinear control techniques are developed to control parallel-plate micro electrostatic actuators in the presence of parasitics and parametric uncertainties. The movable plate of the micro actuator is actively controlled utilizing the measurements of internal charge and movable plate’s displacement. A velocity observer is designed to estimate the velocity of the plate that is ne...

This paper deals with the effect of the intrinsic material length-scale parameter on the stability and natural frequency of a rectangular micro-plate for two different cases; fully clamped and fully simply supported. A variational formulation based on Hamilton’s principle and the modified couple stress theory is used to obtain the nonlinear governing equation of a micro-plate incorporating the ...

Capacitive Micro-machined Ultrasonic Transducers (CMUTs) are the ultrasonic devices which produce better features in contrast to piezoelectric transducers. The intrinsic parameter of CMUT varies with the variation in geometrical dimension of the device. The cavity height and the radius of the CMUT with circular membrane is varied in the lumped parallel plate model for its impact on the paramete...

We report on the design of the two Gregorian adaptive secondary mirrors of the Large Binocular Telescope. Each adaptive secondary is a Zerodur shell having an external diameter of 911 mm and a thickness of about 1.5 mm. The deformable mirror is controlled by a pattern of 918 electromagnetic actuators. Its shape is referred to a stable ULE back plate by means of capacitive sensors co-located to ...