Design and Simulation of Capacitive Pressure Sensor for Blood Pressure Sensing Application

Lecture Notes in Electrical Engineering

Kumar

Mukhiya

2019

Self Cite

In Micro-electro-mechanical Systems (MEMS) based pressure sensors and acoustic devices, deflection of a membrane is utilized for pressure or sound measurements. Due to advantages of capacitive pressure sensor over piezoresistive pressure sensors (low power consumption, less sensitive to temperature drift, higher dynamic range, high sensitivity), capacitive pressure sensors are the 2nd largest useable MEMS-based sensor after piezoresistive pressure sensors. We present a normal capacitive pressure sensor, for continuous sensing of normal and abnormal Intraocular Pressure (IOP). The composite membrane of the sensor is made of three materials, i.e., Si, SiO 2 and Si 3 N 4 . The membrane deflection, capacitance variation, mechanical sensitivity, capacitive sensitivity and non-linearity are discussed in this work. Mathematical modeling is performed for analytical simulation, which is also compared with Finite Element Method (FEM) simulations. MATLAB ® is used for analytical simulations and CoventorWare ® is used for FEM simulations. The variation in analytical result of deflection in membrane w.r.t. FEM result is about 7.19%, and for capacitance, the variation is about 2.7% at maximum pressure of 8 kPa. The nonlinearity is about 4.2492% for the proposed sensor for fabrication using surface micro-machining process.

“…The mechanical sensitivity is slope of maximum deflection versus pressure range curve. The mechanical sensitivity of composite membrane can be given by [2][3]:…”

Section: Sensitivity and Non-linearitymentioning

confidence: 99%

“…The capacitive sensitivity of composite membrane based sensor is obtained by the ratio of change in capacitance and applied pressure range [2][3][4]:…”

Section: Sensitivity and Non-linearitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The normal range of IOP is 1.6 kPa -2.8 kPa. Therefore, the accurate measurement in early stage can save the eye from permanent blindness [2][3].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling and FEM-Based Simulations of Composite Membrane Based Circular Capacitive Pressure Sensor

Lecture Notes in Electrical Engineering

Kumar

Mukhiya

2019

Self Cite

“…Some issues must be addressed by circuitry which is used to measure the change in capacitance. As sealing the vacuum cavity is complex task, so proper care must be been taken at the time of fabrication and packaging the absolute capacitive pressure sensor [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modelling and Comparative Study of Elliptical and Circular Capacitive Pressure Microsensor

Kumar

2019

J. Phys.: Conf. Ser.

Self Cite

A lot of work on clamped circular, square and rectangular shaped capacitive pressure sensor has been carried out. However, to the best of our knowledge, no elaborate work has been performed on mathematical formulation and simulation of clamped elliptical shaped capacitive pressure sensor in literature. This paper describes the mathematical modelling and simulation of normal mode clamped elliptical shaped capacitive pressure sensor. The study of various performance parameters like maximum diaphragm deflection, capacitance variation, mechanical sensitivity, capacitive sensitivity and non-linearity is also carried out for operating pressure range of 0kPa -18 kPa. For circular capacitive pressure sensor, the operating pressure range is modified according to physical dimensions i.e. thickness and radius of diaphragm, separation gap between plates and maximum deflection. For same overlapping area between plates (10000 mm 2 ), the comparison of elliptical shapes of different eccentricities with circular shape diaphragm is carried out. The thickness of diaphragm is taken as2 µm and separation gap is 1 µm in all the designs which are used in this work. In this comparative study, it is observed that elliptical shaped capacitive pressure sensors have better linearity than circular diaphragm pressure sensor.

Recent Progress on Flexible Capacitive Pressure Sensors: From Design and Materials to Applications

Adv Materials Technologies

El‐Atab

Hussain

et al. 2021

195

117

For decades, the revolution in design and fabrication methodology of flexible capacitive pressure sensors using various inorganic/organic materials has significantly enhanced the field of flexible and wearable electronics with a wide range of applications in aerospace, automobiles, marine environment, robotics, healthcare, and consumer/portable electronics. Mathematical modelling, finite element simulations, and unique fabrication strategies are utilized to fabricate diverse shapes of diaphragms, shells, and cantilevers which function in normal, touch, or double touch modes, operation principles inspired from microelectromechanical systems (MEMS) based capacitive pressure sensing techniques. The capacitive pressure sensing technique detects changes in capacitance due to the deformation/deflection of a pressure sensitive mechanical element that alters the separation gap of the capacitor. Due to advancement in state‐of‐the‐art fabrication technologies, the performance and properties of capacitive pressure sensors are enhanced. In this review paper, recent progress in flexible capacitive pressure sensing techniques in terms of design, materials, and fabrication strategies is reported. The mechanics and fabrication steps of paper‐based low‐cost MEMS/flexible devices are also broadly reported. Lastly, the applications of flexible capacitive pressure sensors, challenges, and future perspectives are discussed.