Microelectromechanical Systems Capacitive Pressure Sensor Research Articles

MEMS capacitive pressure sensor: analysis, theoretical modeling, simulation and performance comparison of the effect of a conical notch

Abstract Micro-Electro-Mechanical Systems (MEMS) pressure sensors are widely used in various applications due to their high sensitivity, low power consumption, and compactness. This work involves the design and simulation of a MEMS-based Touch Mode Capacitive Pressure Sensor (TMCPS). The proposed sensor is based on a substrate with an integrated conical notch featuring a circular diaphragm, aiming to enhance the key performance parameters of the sensor. The integration of a conical notch in the substrate increases the touch area between the diaphragm and substrate compared to the literature, ensuring increased capacitance and capacitive sensitivity. In this work the mathematical analysis of deflection of a circular diaphragm employing thin plate theory, capacitance, and capacitive sensitivity, along with step-by-step explanations, is provided. The results are obtained from MATLAB simulations. The deflection of the diaphragm is validated through Finite Element Analysis (FEA) using COMSOL Multiphysics. The proposed work demonstrates a significant improvement in sensor sensitivity compared to the existing literature.

Design and Simulation of Micro-Electro-Mechanical Systems (MEMS) Capacitive Pressure Sensor for Thermal Runaway Detection in the Electric Vehicle

Recent advancement of vehicle technologies has resulted in development of replacing conventional Internal combustion engine (ICE) to Electric Vehicle (EV) mostly powered by Lithium-ion batteries (LIB). These batteries contain massive amount of energy confined in a very small space. Thermal runaway occurs when the batteries and its circuits start to heat up anomaly. Thermal runaway can cause failures that can lead to battery ignition, resulting in explosions and imminent threats to life and property. This research focused on MEMS capacitance pressure sensor, using three distinct square slotted diaphragm designs: clamped-square, four-slotted-square, and eight-slotted-square diaphragms. The investigation commenced with an evaluation of diaphragm performance, and subsequently, the diaphragm was integrated into the structure of the MEMS capacitive pressure sensor and subjected to simulation. Varied pressure levels ranging from 0.1 to 0.35 MPa were applied to both the diaphragm and the pressure sensor. The outcomes revealed that the eight-slotted-square diaphragm yielded the most substantial displacement, registering at 5.507 µm. It also exhibited the highest Mises stress of 644.67 MPa, and recorded the highest mechanical sensitivity at 15.7545 (10-12/Pa). The clamped-square design, despite its slotted area, yielded the highest capacitance value among the three designs for the pressure sensor.

Modeling and analysic of MEMS capacitive pressure sensor using graphene membrane

Micro electromechanical systems (MEMS) based capacitive pressure sensor for ultral-low pressure using graphene has been proposed. The characteristics of sensor such as membrane displacement, capacitance and sensitivity of sensor with external pressure effect are simulated and analyzed using Comsol Multiphysics software. The obtained results show that the MEMS capacitive pressure sensor using 3, 5, 7-layer graphene exhibits the sensitivity of 230.8 aF/Pa, 174.4 aF/Pa and 144.4 aF/Pa, respectively.

Wide-temperature range CMOS capacitance to digital convertor for MEMS pressure sensors

We present a complementary metal-oxide-semiconductor (CMOS) capacitance to digital converter (CDC) for capacitive Microelectromechanical Systems (MEMS) pressure sensors, that is functionally tested over a wide temperature range from −20°C to 225°C. The proposed circuit uses a sigma–delta technique to convert the input ratio between sensor and reference capacitors into a digital output. A constant-gm biasing technique is used to alleviate performance degradation at high temperatures. The circuit is implemented using the IBM 0.13μm CMOS process technology which incorporates a 2.5V power supply. The simulation results show that the circuit offers 0.03% accuracy between −55°C and 225°C. The circuit is tested with a commercial MEMS capacitive pressure sensor. Experimental results show that the circuit offers good temperature stability, resolution of 1.44fF, and accuracy of 2.4% between −20°C and 225°C.

High Reliability of MEMS Packaged Capacitive Pressure Sensor Employing 3C-SiC for High Temperature

Abstract This study develops the prototype of a micro-electro-mechanical systems (MEMS) packaged capacitive pressure sensor employing 3C-SiC diaphragm for high temperature devices. The 3C-SiC diaphragm is designed with the thicknesses of 1.0 μm and the width and length of 2.0 mm x 2.0 mm. The fabricated sensor is combined with a reliable stainless steel o-ring packaging concept as a simple assembly approach to reduce the manufacturing cost. There is an o-ring seal at the sensor devices an advantageous for high reliability, small size, lightweight, smart interface features and easy maintenance services. The stability and performance of the prototype devices has been tested for three test group and measured by using LCR meter. The prototypes of MEMS capacitive pressure sensor are characterized under static pressure of 5.0 MPa and temperatures up to 500 °C in a stainless steel chamber with direct capacitance measurement. At room temperature (27 °C), the sensitivity of the sensor is 0.0096 pF/MPa in the range of pressure (1.0–5.0 MPa), with nonlinearity of 0.49%. At 300 °C, the sensitivity is 0.0127 pF/MPa, and the nonlinearity of 0.46%. The sensitivity increased by 0.0031 pF/MPa; corresponding temperature coefficient of sensitivity is 0.058%/°C. At 500 °C, the maximum temperature coefficient of output change is 0.073%/°C being measured at 5.0 MPa. The main impact of this work is the ability of the sensor to operate up to 500 °C, compare to the previous work using similar 3C-SiC diaphragm that can operates only 300 °C. The results also show that MEMS packaged capacitive pressure sensor employing 3C-SiC is performed high reliability for high temperature up to 500 °C. In addition, a reliable stainless steel o-ring packaging concept of MEMS packaged capacitive pressure sensor.

RETRACTED ARTICLE: A MEMS packaged capacitive pressure sensor employing 3C-SiC with operating temperature of 500 °C

This study develops the prototype of a micro-electro-mechanical systems (MEMS) packaged capacitive pressure sensor employing 3C-SiC thin film as a diaphragm. The details of the design and fabrication steps involved bulk micromachining process. The 3C-SiC-on-Si wafer is back-etched the bulk Si to leave 3C-SC thin film by applied ProTEK PSB coating as a newly photosensitive layer. The ProTEK PSB is exposed into desired pattern of MEMS capacitive pressure sensor and the exposed pattern is developed by developer (ethylene lactate). The photosensitive can be stripped off with strong combination acid such as 2-(1-methoxy)propyl acetate, ethyl acetoacetate and photoacid generator which is attack the exposed ProTEK PSB while unexposed ProTEK PSB areas remain contact the alignment on the wafer surfaces. The prototypes of a MEMS capacitive pressure is packaged for high temperature up to 500 °C and characterized under static pressure of 5.0 MPa in a stainless steel chamber with direct capacitance measurement using LCR meter. The diaphragm of 3C-SiC thin film has the thicknesses of 1.0 µm and the size of 2.0 mm × 2.0 mm. At room temperature (27 °C), the sensitivity of the sensor is 0.00962 pF/MPa in the range of (1.0---5.0 MPa), with nonlinearity of 0.49 %. At 300 °C, the sensitivity is 0.0127 pF/MPa, and nonlinearity of 0.46 %. The sensitivity increased by 0.0031 pF/MPa, corresponding temperature coefficient of sensitivity is 0.058 %/°C. At 500 °C, the maximum temperature coefficient of output change is 0.073 %/°C being red at 5.0 MPa. The main impact of this work is the ability of the sensor to operate up to 500 °C, compare to the previous work using similar 3C-SiC diaphragm that can operates only 400 °C. In addition, a reliable stainless steel o-ring packaging concept is proposed as a simple assembly approach to reduce the manufacturing cost. There is an o-ring seal a this sensor is designed for high reliability, small size, lightweight, smart interface featured and easy cleaning service in the field which is relatively easy to replace without the need for special skill or tools in short period of time.

Modeling and Analysis of Thin Film PolySi Diaphragm Pressure Sensor

Micromachining technology has greatly benefited from the success of developments in implantable biomedical micro devices. In this paper, a simulation solution of micro-electro mechanical systems (MEMS) capacitive pressure sensor operating for biomedical applications in the range of 20–400 mmHg was designed. Employing the micro electro mechanical systems (MEMS) technology, high sensor sensitivities and resolutions have been achieved. This paper provides initial data on the design and simulation of such a sensor. Capacitive sensing uses the diaphragm deformation-induced capacitance change. The sensor composed of a rectangular Polysilicon diaphragm that deflects due to pressure applied over it. Applied pressure deflects the 2 μm diaphragm changing the capacitance between the Polysilicon diaphragm and gold flat electrode deposited on a glass pyrex substrate. The simulation of the MEMS capacitive pressure sensor achieves good linearity and large operating pressure range. The static and thermo electro mechanical analysis was performed. The FEA modeling and simulated data results were generated. The capacitive response of the sensor performed as expected according to the relationship of the spacing of the plates. Intellisuite software is used for modeling and simulation of MEMS capacitive pressure sensor to optimize the design, improve the performance and to reduce the time of fabricating process of the device.

Simulation Analysis of MEMS Based Capacitive Differential Pressure Sensor for Aircraft Application

In this paper, simulation solution for Microelectromechanical systems (MEMS) based capacitive differential pressure sensor for aircraft altimeter is proposed. The principle of proposed MEMS capacitive differential pressure sensor design was explained. Analysis for the measurement of center deflection and capacitive sensitivity square diaphragm membrane was done. Simulation on deflection and capacitive sensitivity was carried out for the range of pressure from 100mbar to1100mbar. Gold, diaphragm membrane was used in this analysis. Analysis result shows, linear variation on center deflection and capacitance variation which is more suitable for this application.

Simulation of Low Pressure MEMS Sensor for Biomedical Application

Micromachining technology has greatly benefited from the success of developments in implantable biomedical microdevices. In this paper, microelectromechanical systems (MEMS) capacitive pressure sensor operating for biomedical applications in the range of 20–400 mm Hg was designed. Employing the microelectromechanical systems technology, high sensor sensitivities and resolutions have been achieved. Capacitive sensing uses the diaphragm deformation-induced capacitance change. The sensor composed of a rectangular polysilicon diaphragm that deflects due to pressure applied over it. Applied pressure deflects the 2 µm diaphragm changing the capacitance between the polysilicon diaphragm and gold flat electrode deposited on a glass Pyrex substrate. The MEMS capacitive pressure sensor achieves good linearity and large operating pressure range. The static and thermo electromechanical analysis were performed. The finite element analysis data results were generated. The capacitive response of the sensor performed as expected according to the relationship of the spacing of the plates.

Novel Capacitive Pressure Sensor

A new microelectromechanical-systems capacitive pressure sensor with extremely high sensitivity (2.24 ¿F/kPa) is introduced. The sensor essentially consists of a small drop of mercury and a flat aluminum electrode that are separated by a 1 ¿m-thick layer of Barium Strontium Titanate (a high dielectric-constant ceramic). The assembly constitutes a parallel-plate capacitor where the surface area of the electrodes is variable to a high degree. The mercury drop is pressured by a small corrugated metal diaphragm. As the electrode area of the parallel-plate capacitor varies, a total change in capacitance of more than 6 ¿F is obtained.