Deflection Of Diaphragm Research Articles

On effect of viscoelastic characteristics of polymers on performance of micropump

Micropumps are the most important components of lab-on-a-chip devices, which are becoming popular recently due to their enormous advantages. Among the different designs of micropumps, the nozzle–diffuser valveless design is the most preferred one due to simplicity in manufacturing. For the simulation of these pumps, the local fluid–structure interaction modeling is important to get the performance accuracy. To capture fluid–structure interaction accurately, an appropriate selection of the fluid as well as the structural modeling approaches are very essential. It is well known that the polydimethylsiloxane materials behave as a viscoelastic material. However, most of the earlier studies on polydimethylsiloxane micropump modeling have considered polydimethylsiloxane as a linear elastic material. In this article, a nozzle–diffuser-based valveless micropump is modeled using a fluid–structure interaction approach along with a linear viscoelastic model for polydimethylsiloxane. The mechanical properties of the polydimethylsiloxane material are experimentally obtained using dynamic mechanical analysis for the range of micropump operating frequencies. These viscoelastic properties of polydimethylsiloxane, with varying proportionate of curing agent, are introduced in the fluid–structure interaction model of micropump using the Kelvin–Voigt model. The results are presented in the form of micropump performance parameters such as diaphragm deflection, von-Mises stresses, swept volume, and fluid flow rate.

FEM Analysis of Ultrasonic Transducer with Square and Circular Diaphragm

The objective of the paper is to design a Microelectronic Mechanical Systems(MEMS) based Capacitive Micromachined Ultrasonic Transducer (CMUT) which has been found to be superior in terms of bandwidth, transduction efficiency and array fabrication as compared to conventional piezoelectric transducers. With the years CMUT has been shown with different element geometries and fabrication techniques, however the optimization techniques and the application areas for the device persist. In this paper CMUT is simulated in COMSOL with Square and Circular diaphragm. FEM analysis is being carried out considering the same area for both the geometries in 3D.CMUT dynamics have been modeled by combining the Electrostatic module, Solid Mechanics Module and Mesh modules in COMSOL. The distributed stress and electric field are measured as function of time. This gives the exact comparison for the Eigen frequency, pull in voltage, deflection with applied DC bias and deflection of the diaphragm with AC superimposed on DC considering the isotropic Silicon as the diaphragm material. This simulation work provides results for the researcher to conclude on the geometry of the device prior to fabrication.

Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers.

Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding. The measured resonant frequency of 19.3 MHz using a Polytec™ laser Doppler vibrometer (Polytec™ MSA-500) is in excellent agreement with the 3-D FEA simulation result using IntelliSuite™. An Agilent ENA5061B vector network analyzer (VNA) has been used for impedance measurement and the resonance and anti-resonance values from the imaginary impedance curve were used to determine the electromechanical coupling co-efficient. The measured coupling coefficient of 0.294 at 20 V DC bias exhibits 40% higher transduction efficiency as compared to a measured value published elsewhere for a silicon nitride based CMUT. A white light interferometry method was used to measure the diaphragm deflection profiles at different DC bias. The diaphragm center velocity was measured for different sub-resonant frequencies using a Polytec™ laser Doppler vibrometer that confirms vibration of the diaphragm at different excitation frequencies and bias voltages. Transmit and receive operations of CMUT cells were characterized using a pitch-catch method and a −6 dB fractional bandwidth of 23% was extracted from the received signal in frequency domain. From the measurement, it appears that BCB-based CMUTs offer superior transduction efficiency as compared to silicon nitride or silicon dioxide insulator-based CMUTs, and provide a very uniform deflection profile thus making them a suitable candidate to fabricate highly energy efficient CMUTs.

Design and Manufacturing of a Passive Pressure Sensor Based on LC Resonance.

The LC resonator-based passive pressure sensor attracts much attention because it does not need a power source or lead wires between the sensing element and the readout system. This paper presents the design and manufacturing of a passive pressure sensor that contains a variable capacitor and a copper-electroplated planar inductor. The sensor is fabricated using silicon bulk micro-machining, electroplating, and anodic bonding technology. The finite element method is used to model the deflection of the silicon diaphragm and extract the capacitance change corresponding to the applied pressure. Within the measurement range from 5 to 100 kPa, the sensitivity of the sensor is 0.052 MHz/kPa, the linearity is 2.79%, and the hysteresis error is 0.2%. Compared with the sensitivity at 27 °C, the drop of output performance is 3.53% at 140 °C.

Singularly perturbed BVP to estimation of diaphragm deflection in MEMS capacitive microphone: An application of ADM

In this paper, we implement the Adomian decomposition method (ADM) to approximate the deflection of polysilicon diaphragm with small flexural rigidity of Micro Electro Mechanical System (MEMS) capacitive microphone. We prove the existence and the uniqueness of the solution of considered problem with the help of the theory of semi-group. Special attention is given to prove the convergence of the implemented method. Numerical simulation and comparison between the approximate solutions by using the ADM with the variational iteration method are given.

Modeling and analysis of a novel combined peninsula–island structure diaphragm for ultra-low pressure sensing with high sensitivity

A novel combined peninsula–island structure diaphragm has been developed with four pairs of peninsula and island structures as well as four gaps between them. When a pressure is applied to the diaphragm, the major strain energy of the diaphragm is locked in the position above each gap, which is called the stress concentration region (SCR). Also, minimal strain energy is wasted outside the SCR. Therefore, this novel diaphragm is favorable in obtaining high sensitivity for a micro-electromechanical system piezoresistive ultra-low pressure sensor. In order to optimize the diaphragm structure, the partial differential equation governing the diaphragm deflection has been given under pressure. The theoretical analysis solutions are obtained based on the theory of the Navier trigonometric series and the mirror image method, and in accordance with the finite element method simulation results. Finally, a sensor with the proposed diaphragm is designed with the working range of 0–500 Pa and has sensitivity above 0.055 mV V−1 Pa−1. In comparison to a flat diaphragm with the same dimensions, this novel diaphragm achieves a sensitivity level increased by 256%, a nonlinearity reduced by 79%, and a resonance frequency increased by 5.5%. In addition, the proposed theoretical analysis solution of the diaphragm can also be applied to other kinds of diaphragm with different islands to achieve optimization.

Realization of MOEMS pressure sensor using mach zehnder interferometer

In this paper we first time realize the all optical pressure sensor using the Mach Zehnder interferometer. In this study, initially a circular shape clamped diaphragm is taken and pressure is applied. The deflection which is maximum at the centre is taken across a potentiometer (POT hereafter) and corresponding output voltage is noted. This voltage is applied across the electrode of Mach Zehnder Interferometer (MZI) and depending upon the specific value of electrode voltage the intensity of the optical signal varies, which provides the proper relation between the applied pressure and normalized intensity of the optical signal. The optical switching phenomena in the MZI structure can be effectively used as an efficient pressure sensors. The paper includes the suitable expressions for the central deflection of clamped edge pressure sensor diaphragm, the voltage output by POT and intensity of optical signal for MZI. The results are very effectively supported by the use of Solidworks and Opti-BPM. The error for the said parameters is also calculated and it is found in good agreement with the desired results.

Thermally Stable Nonuniform Microcorrugated Capacitive MEMS Tuner

This letter reports for the first time a thermally stable capacitive microelectromechanical systems tuner based on a circular nonuniform microcorrugated diaphragm (NMCD) suitable for resonators/filters, which require a large tuning displacement (>10 μm). The temperature-induced center offset of the NMCD is reduced by 13.5× with a temperature variation of ΔT = 100 °C compared with the case of uniform microcorrugated diaphragms, which allow the NMCD to be continuously tunable in the full desired range. Moreover, the change of the actuation voltage required for a 10-μm diaphragm deflection is reduced from 51.5% to 10.4% with ΔT = 45 °C.

Computer aided modeling for a miniature silicon-on-insulator MEMS piezoresistive pressure sensor

Abstract The silicon-on-insulator diaphragm structure is a combined structure of the silicon dioxide and silicon layer. This work presents a new method to estimate the deflection response of silicon with that of a silicon-on-insulator (SOI) diaphragm structure, based on the burst pressure design approach. It also evaluates the output voltage of the diaphragm under two different conditions, flipped and un-flipped. The new modified analytical model developed and presented in this paper for describing the load deflection of SOI diaphragm is able to predict the deflection accurately when compared with the results obtained by finite element analysis CoventorWare®.

Laser Doppler vibrometry experiment on a piezo-driven slot synthetic jet in water

The present study deals with a slot synthetic jet (SJ) issuing from an actuator into quiescent surroundings and driven by a piezoceramic transducer. The actuator slot width was 0.36 mm, with a drive frequency proposed near the theoretical natural frequency of the actuator. The working fluid was water at room temperature. The present experiments used flow visualization (a laser-induced fluorescence technique) and laser Doppler vibrometry methods. Flow visualization was used to identify SJ formation, to demonstrate its function, and to estimate SJ velocity. Laser Doppler vibrometry was used to quantify diaphragm displacement and refine operating parameters. Phase averaging yielded a spatial and temporal diaphragm deflection during the actuation period. Taking incompressibility and continuity into consideration, the velocity in the actuator slot and the Reynolds number of the SJ were evaluated as 0.21 m/s and 157, respectively. The present results confirmed a SJ actuator function at the resonance frequency of approximately 46 Hz, which corresponds closely with the theoretical evaluation. The laser Doppler vibrometry results corresponded closely with an estimation of SJ velocity by the present flow visualization.

A high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging.

This paper presents a high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging. An approach to maintaining high-vacuum conditions by integrating the MEMS fabrication process with getter material preparation is presented in this paper. In this device, the pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in “H” type doubly-clamped micro resonant beams, leading to a resonance frequency shift. The device geometries were optimized using FEM simulation and a 4-inch SOI wafer was used for device fabrication, which required only three photolithographic steps. In the device fabrication, a non-evaporable metal thin film as the getter material was sputtered on a Pyrex 7740 glass wafer, which was then anodically bonded to the patterned SOI wafer for vacuum packaging. Through-glass via holes predefined in the glass wafer functioned as the electrical interconnections between the patterned SOI wafer and the surrounding electrical components. Experimental results recorded that the Q-factor of the resonant beam was beyond 22,000, with a differential sensitivity of 89.86 Hz/kPa, a device resolution of 10 Pa and a nonlinearity of 0.02% F.S with the pressure varying from 50 kPa to 100 kPa. In addition, the temperature drift coefficient was less than −0.01% F.S/°C in the range of −40 °C to 70 °C, the long-term stability error was quantified as 0.01% F.S over a 5-month period and the accuracy of the microsensor was better than 0.01% F.S.

A Microdischarge-Based Monolithic Pressure Sensor

This paper describes the investigation of a microdischarge-based approach for sensing the diaphragm deflection in a monolithically fabricated pressure sensor. This transduction approach is appealing from the viewpoint of miniaturization. The device consists of a deflecting Si diaphragm with a sensing cathode, and a glass substrate with an anode and a reference cathode. The total exterior volume of the device is 0.05 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ; typical electrode size and separations are 35 and 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Pulsed microdischarges are initiated in a sealed chamber formed between Si and glass chips, and are filled with Ar gas. External pressure deflects the Si diaphragm and changes the interelectrode spacing, thereby redistributing the current between the anode and two competing cathodes. The differential current is indicative of the diaphragm deflection which is determined by the external pressure. A 6-mask microfabrication process is investigated for device fabrication. Electrode connections to the interior of the chamber are provided by laser drilling and copper electroplating through high aspect ratio glass vias. The Si and glass substrates are bonded by Au-In eutectic. The redistribution of plasma current between competing cathodes, as a consequence of diaphragm deflection over a range of pressure, was experimentally demonstrated. First principles modeling of transient microdischarges have provided insights to the fundamental processes responsible for the differential current and guidance for scaling the device to smaller dimension.

Theoretical and experimental investigation of the trapped air effect on air-sealed capacitive pressure sensor

This study presents the effect of the air trapped in the cavity on the performance of an air-sealed capacitive pressure sensor investigated by theoretical analysis and experimental validation. As a result, the sensitivity of a typical air-sealed capacitive pressure sensor can be improved significantly by adopting additional air chamber to increase the trapped air volume of the sensor. For theoretical analysis, the diaphragm deflection and the relative capacitance change of the sensor are formulated by considering the air pressure within the cavity affected by the diaphragm deflection and ambient temperature. In experiments, a passive wireless LC resonant telemetry scheme is employed to monitor the applied pressure by integrating an inductor coil with the fabricated sensor. The obtained result of the sensor having a flexible diaphragm such a natural rubber latex (NRL) shows the sensitivity improved more than 15 times by employing additional air chamber at room temperature compared to that of the sensor without it. Consequently, the test result of the NRL sensor with additional air chamber shows a pressure sensitivity of 8986ppm/kPa and a pressure responsivity of 1.391MHz/kPa in the pressure range of 1–10kPa. In addition, the effect of ambient temperature on the response of the air-sealed capacitive pressure sensor is measured and examined through comparison with the analytical results.

A high sensitive FBG pressure sensor using thin metal diaphragm

A high sensitive pressure sensor using fiber Bragg grating (FBG), integrated with thin metal diaphragm is designed and investigated both theoretically and experimentally. Under pressure the diaphragm deflection causes an axially stretched-strain along the length of the FBG. The pressure sensitivity of the sensor gained from the test results is 2.05 × 10−2 MPa−1, approximately four orders of magnitude higher than that can be measured with the bare FBG. Experimental results showed good agreement with the proposed theoretical results.

A SOI-MEMS Based Resonant Barometric Pressure Sensor with Differential Output

This paper presents a laterally driven resonant barometric pressure sensor fabricated using SOI-MEMS technology. In this device, pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in H style doubly-clamped micro beams, leading to resonant frequency shift. In device fabrication, SOI-MEMS fabrication processes were utilized, where a new modified buffered hydrofluoric acid (BHF) solution was used to remove the buried oxide layer and release the suspended resonant beams. Experimental results recorded a device resolution of 10Pa, a nonlinearity of 0.04% and a temperature coefficient of-0.04% F.S/°C in the range of-40°C to 30°C. The long-term stability error of the proposed device was quantified as 0.05% F.S over the past 3 months.

Hydrodynamic focusing micropump module with PDMS/nickel-particle composite diaphragms for microfluidic systems

In this research, a rapid prototype hydrodynamic focusing module with three multi-fluidic speed-modulating (MFSM) micropumps in micro-fluidic flow has been designed, fabricated, and characterized. The module comprises of three MFSM micropumps having the dimension of 33 × 25 × 5 mm to achieve hydrodynamic focusing and the stream modulation. Each micropump consists of top, middle and bottom including actuation/modulation source, PDMS/nickel-particle composite (PNPC) diaphragm and Tesla-type valve/chamber, respectively. Three MFSM micropumps share one pneumatic actuation source and two individual permanent magnet modulation sources which are located above the right and left diaphragms. Each permanent magnet is manually controlled by a screw. The PNPC diaphragm deflection is obtained by the external pneumatic force, and the permanent magnet limits the displacement resulting from the interaction between the magnetic field and the nickel particles of the PNPC diaphragm. Hydrodynamic focusing is realized by the flow rate control of two side micropumps with magnetic diaphragm displacement modulation. Analyses of the magnetic modulation field, the flow rate of the MFSM micropump, and the hydrodynamic focused stream modulation are presented. The individual micropump can pump DI water with a flow rate of about 107 μl/min, and the hydrodynamic focusing channel can achieve a flow rate of about 321 μl/min, under the frequency of 2 Hz. This research examines the modulation feasibility of hydrodynamic focused center stream by controlling the neighboring stream flow rate and this technique can be utilized for possible applications in lab-on-a-chip, micro total analysis system and point of care testing system.

Analyzing the transition pressure and viscosity limit of a hydroelastic microfluidic oscillator

We analyze the transition of a hydroelastic microfluidic oscillator from steady laminar flow to oscillatory flow. Results show that the transition pressure is influenced by both the fluid viscosity and the device geometry, which can be explained through the negative differential resistance effects. Due to the deflection of the elastic diaphragm, the flow resistance increases with the driving pressure (P0), and this increase is more significant at higher viscosities. At the critical transition point, further increase of P0 will cause a reduction in the flow rate and trigger the oscillation. This provides an alternative point of view to the occurrence of flow induced vibrations. We also demonstrate that through optimization of the design, the current device is capable of working in high-viscosity environments of up to 89 cP.

The Mechanical and Electrical Effects of MEMS Capacitive Pressure Sensor Based 3C-SiC for Extreme Temperature

This paper discusses the mechanical and electrical effects on 3C-SiC and Si thin film as a diaphragm for MEMS capacitive pressure sensor operating for extreme temperature which is 1000 K. This work compares the design of a diaphragm based MEMS capacitive pressure sensor employing 3C-SiC and Si thin films. A 3C-SiC diaphragm was bonded with a thickness of 380 μm Si substrate, and a cavity gap of 2.2 μm is formed between the wafers. The MEMS capacitive pressure sensor designs were simulated using COMSOL ver 4.3 software to compare the diaphragm deflection, capacitive performance analysis, von Mises stress, and total electrical energy performance. Both materials are designed with the same layout dimensional with different thicknesses of the diaphragm which are 1.0 μm, 1.6 μm, and 2.2 μm. It is observed that the 3C-SiC thin film is far superior materials to Si thin film mechanically in withstanding higher applied pressures and temperatures. For 3C-SiC and Si, the maximum von Mises stress achieved is 148.32 MPa and 125.48 MPa corresponding to capacitance value which is 1.93 pF and 1.22 pF, respectively. In terms of electrical performance, the maximum output capacitance of 1.93 pF is obtained with less total energy of 5.87 × 10−13 J, thus having a 50% saving as compared to Si.

Accurate Model of Capacitance for MEMS Sensors using Corrugated Diaphragm with Residual Stress

In this paper, we present a new model for calculating the capacitance of MEMS sensor with corrugated diaphragm. In this work, the effect of residual stress is considered on deflection of diaphragm and capacitance of sensor. First, a new analytical analyzes have been carried out to derive mathematic expression for central deflection of corrugated diaphragm and its relationship with residual stress. Then, the capacitance and sensitivity of sensor using corrugated diaphragm with residual stress are calculated under bias voltage and pressure. The analytical results are compared with simulation using a Finite Element Method (FEM). The results show that the new analytical model is very close with simulation results.

Verifying finite element simulation in miniature silicon based stacked diaphragm pressure sensors

Micro electro mechanical system are usually defined as highly miniaturized devices combining both electrical and mechanical components that are fabricated using integrated circuit batch processing techniques. Silicon based stacked diaphragm structure is a combination of silicon-di-oxide and the silicon layer. This work brings out a new approach of finding the sensitivity of stacked diaphragm with respect one of the important parameters like deflection. The sensitivity is also evaluated under thermal effect and, the analytical model developed for the same closely matches with the finite element model. The doping concentration of 1017cm-3, in which single silicon shows maximum sensitivity has been selected and an increase in the sensitivity is observed on using a stacked diaphragm structure. The stacked diaphragm structure is designed, simulated and compared with existing single diaphragm design with respect to diaphragm deflection and sensor output voltage for linearity over a wider range. The effect of the buried oxide in the stacked diaphragm structure is also considered in this work. The work in this paper provides a mathematical expression for realizing the effect of boron implanted resistors on the stacked diaphragm structure. The simulation result reported in the literature evaluates the deflection at a particular temperature but the new analytical model developed in this paper evaluates the sensitivity of the diaphragm over a temperature range.