An Accurate Study on Capacitive Microphone with Circular Diaphragm Using a Higher Order Elasticity Theory

Abstract

This study has been undertaken to investigate the mechanical behavior of the capacitive microphone with clamped circular diaphragm using modified couple stress theory in comparison to the classical one. Presence of the length scale parameter in modified couple stress theory provides the means to evaluate the size effect on the microphone mechanical behavior. Investigating Pull-in phenomenon and dynamic behavior of the microphone are the matters provided due to the application of a step DC voltage. Also the effects of different air damping coefficients on dynamic pull-in voltage and pull-in time have been studied. The output level or sensitivity of the microphone has been studied by investigating the frequency response in term of magnitude for different length scale parameters to figure out how the length scale parameter affects on the sensitivity of the capacitive microphone. To achieve these ends, the nonlinear differential equation of the circular diaphragm has been extracted using Kirchhoff thin plate theory. Then, a Step-by-Step Linearization Method (SSLM) has been used to escape from the nonlinearity of the differential equation. Afterwards, Galerkin-based reduced-order model has been applied to solve the obtained equation.

Quality Factor of Free In-plane Vibration of a Fully Clamped Rectangular Micro-plate

“…Thereby, it can be approximated in terms of linear combinations of a finite number of shape functions and time-dependent coefficients [31,32]. By substituting Equation 13into Equation 10 By substituting Equation (15) into Equation (16) and simplifying it for the first mode of displacements in x and y directions, the first mode of heat in y direction and the second mode of heat in x direction, results can be described as:…”

“…Furthermore, Rezazadeh et al [12] studied TED in a micro-beam resonator based on modified couple stress theory and Zhong et al [13] investigated TED in a micro-plate resonator using modified couple stress. The mentioned theory is utilized to capture the size effect where there is a considerable internal length scale parameter [14,15].…”

Nonlinear vibration analysis of partially coated circular microplate under electrostatic actuation

“…Karimzadeh et al [10] studied the size-dependent dynamic behavior of circular rings on elastic foundation using modi ed couple stress theory. The mechanical behavior of a capacitive microphone with a clamped circular diaphragm was studied by Dowlati et al [11] using modi ed couple stress theory. They obtained the governing equation of motion by using Kirchho thin plate theory.…”

Static analysis and simulation of piston coupled diaphragm for microelectromechanical systems based high sensitive sensors

“…In addition, microphones are used for controlling and recording audio, ultrasonic and subsonic signals since they can function similar to pressure sensors. As ultrasonic waves enable manufacturing of different sensors to be used in measuring diverse parameters such as flow rate, speed, distance, angle, temperature and humidity [7][8][9][10], these sensors or actuators are doubly significant. The diaphragm is an important part of MEMS mechanical sensors.…”