Membrane Deflection Research Articles

Analysis of pressure-induced deviation of the cricothyroid membrane among pediatric patients

BackgroundsHypoxemia develops more quickly in children than in adults due to their high oxygen consumption relative to their body weight and small functional residual capacity. Therefore, cricothyroid puncture must be performed promptly in cannot-intubate and cannot-ventilate situations. However, the success rate of cricothyroid puncture in children is <1%. We hypothesized that the low success rate of cricothyroid puncture in children may be related to the cricothyroid membrane's hypermobility. The aim of the present study was to measure the deviation of the cricothyroid membrane from the midline when applying compressive pressure.MethodsAfter obtaining institutional ethics committee approval, written informed consent was obtained from the patients’ parents. Children aged from 1 month to 15 years who had undergone scheduled operations under general anesthesia and with an American Society of Anesthesiologists Physical Status Classification grade of 1 or 2 were enrolled in this study. The patients were divided into the following four different age groups: 1 month–1 year, 2–4 years, 5–10 years, and 11–15 years. After the intravenous injection of fentanyl, propofol, and rocuronium, the airway was identified using a linear hockey stick ultrasound probe. The cricothyroid membrane was compressed with a force of 5 newtons (N), and cricothyroid membrane deflection was recorded. The primary outcome was the cricothyroid membrane deviation from the midline relative to the tracheal diameter.ResultsTwenty patients were enrolled in this study. No adverse events were noted. The mean cricothyroid membrane deviations from the midline divided by the tracheal diameter was 0.16 ± 0.09, 0.05 ± 0.04, 0.04 ± 0.04, and 0.02 ± 0.03 in children aged 1 month–1 year, 2–4 years, 5–10 years, and 11–15 years, respectively.ConclusionThe cricothyroid membrane deviation due to the application of a compressive force to the overlying skin tended to be larger in younger patients.

Fabrication and Characterization of Dome-Shaped Actuator Membrane for Peristaltic Valveless Electromagnetic Micropump

This paper discusses the method of fabrication and characterization of a peristaltic micropump with a dome-shaped electromagnetic (EM) actuator membrane by pouring Polydimethylsiloxane (PDMS) on top of the glass master mould. The peristaltic micropumps have three membranes separated by a spacer of 2 mm. The structure of the mould consists of three pillar-shaped glasses that have a dome-like structure at the top. The border on the edge of the mould functions as a barrier to prevent the spill of the PDMS. When the PDMS is poured on top of the glass mould, a thin membrane will be formed and it will automatically overflow to form a chamber and spacer. The fabricated membrane structures were characterized using Scanning Electron Microscopy (SEM), while the mechanical and electrica properties were analysed by observing the deformation of the membrane. The SEM images show that a hanging PDMS membrane with a thickness of 77.5 µm was established. The permanent magnet connected to the lever and attached to the membrane will interact with the magnetic field generated by the EM coil. The measurement results show that a coil of 275 turns carrying a current of 600 mA produces a magnetic field of 11 mT causing a membrane deflection of 1.5 mm. The resulting dome-shaped membrane will have its potential application for the use as the actuator for the EM peristaltic micropumps.

Amplifying the power density in thermoacoustic systems using a spring component.

This paper deals with the introduction of a spring component into a thermoacoustic system to increase the power density. This enables more compact and cheaper thermoacoustic systems. A theoretical and experimental study is presented to demonstrate the effect of the introduction of a spring component to amplify the thermal power in a thermoacoustic heat pump. The required spring constant is determined using an electrical circuit analogy model and a DeltaEC model of an existing heat pump. This is calculated for two locations in the system at the cold and hot side of the regenerator. The theory of the deflection of an elastic membrane loaded by a uniform pressure differential is used to calculate the required pretension of an elastic membrane used as spring to obtain the required spring constant. Elastic membranes are prepared and tested in the heat pump. The experimental results show that the insertion of the membrane at the hot side of the regenerator increases the power density by about 20%. The implementation of the membrane at the cold side of the regenerator increases the thermal power by about 100%. For both cases the improvement in the coefficient of performance is about 10%.

Gravity wave interaction with a heaving membrane above a thick porous bed

The present study analyzes diffraction and radiation phenomena of oblique waves interacting with a heaving floating membrane in the presence of a thick porous bed. Following the linear water wave theory, the physical problem is framed mathematically. The significance of the article resides in the following: (1) progressive wave analysis (water and membrane-covered region), (2) solving the boundary value problem (BVP) using the matched eigenfunction expansion method for diffraction and radiation problems, and (3) numerical illustration of various hydrodynamic coefficients for different membrane and porous bed parameters. Bragg scattering with varying frequency is observed for smaller values of membrane tension. Also, the present study demonstrates that the number of oscillations experienced by the reflection coefficient increases proportionally with the length of the membrane. Furthermore, cut-off membrane properties exist at a given frequency for which the zero minimum of wave force is obtained. Also, the porous bed's thickness impacts wave reflection and membrane deflection significantly. Thus, we found that the maximum reflection is observed for a fully permeable bed; however, it decreases with a decrease in the porosity of the porous medium because of its dissipative nature. Conversely, the added mass and damping coefficient increases with increased membrane length. The collective numerical observations for both diffraction and radiation provide insight into resonance phenomena, the role of membrane properties, and the intricate relationship between wave characteristics and membrane properties. The findings from this study could assist geologists and marine engineers in designing and managing ports and harbor infrastructure.

Role of topographical disturbances on hydroelastic response of a floating membrane over a slippery bottom

Some disruptions occur at the bottom of the sea due to underwater explosions and natural disasters (e.g. tsunamis, submarine earthquakes, landslides, rock and asteroid falls, drastic changes in weather conditions, etc.). The current paper aims to study how a transitory ground disturbance affects the membrane deflection in a viscous fluid over a porous slippery bottom at a finite water depth in the presence of a floating elastic membrane. Three types of ground disturbance are considered such as H 0 ( x ) = δ ( x ) , H 0 ( x ) = e ( − x 2 / 2 ) and H 0 ( x ) = e − | x | Kundu et al. [Waves generated on running stream due to a disturbance on sea bed. Int J Appl Comput Math. 2020;6(2):1–17.] and Maiti and Mandal [Waves generated by bottom disturbance in an ice-covered ocean. Int J Appl Mech Eng. 2007;12(2):477–486.]. The Stokes stream function and wave potential boundary value problems are used to formulate this problem. The membrane deflection is obtained as infinite integrals using the Fourier, and Laplace transforms. These integrals are then evaluated using the steepest descent method. The effects of the bottom slip parameter, the fluid's viscosity, and the floating membrane's tension and mass on the membrane deflection are analyzed. The study reveals that the amplitude of the membrane deflection decreases, and the oscillatory pattern of the deflection curve is changed by reducing the value of viscosity. Furthermore, the membrane's deflection amplitude decreases with an increase in the values of mass and tension of the floating membrane. Moreover, the slippery bottom plays a vital role in reducing the amplitude of the membrane deflection.

Elastohydrodynamic interactions in soft hydraulic knots

Soft intertwined channel systems are frequently found in fluid flow networks in nature. The passage geometry of these systems can deform due to fluid flow, which can cause the relationship between flow rate and pressure drop to deviate from the Hagen–Poiseuille linear law. Although fluid–structure interactions in single deformable channels have been extensively studied, such as in Starling's resistor and its variations, the flow transport capacity of an intertwined channel with multiple self-intersections (a ‘hydraulic knot’), is still an open question. We present experiments and theory on soft hydraulic knots formed by interlinked microfluidic devices comprising two intersecting channels separated by a thin elastomeric membrane. Our experiments show flow–pressure relationships similar to flow limitation, where the limiting flow rate depends on the knot configuration. To explain our observations, we develop a mathematical model based on lubrication theory coupled with tension-dominated membrane deflections that compares favourably with our experimental data. Finally, we present two potential hydraulic knot applications for microfluidic flow rectification and attenuation.

Membrane‐based mechanical characterization of screen‐printed inks: Deflection analysis of ink layers on polyimide membranes

AbstractMeasurements of Young's modulus and residual stresses of screen‐printed ink layers using a bulge test on coated polyimide‐based membranes are proposed in this work. The applied bulge test monitors the deflection of membranes under pressure with interferometry. The obtained Young's modulus ranges from 6 to 8 GPa for a carbon blend‐based ink and is around 12 GPa for a silver nanoparticle ink. These values are compared with standard nanoindentation and show good agreement. Besides, the residual stresses range from −4 to 8 MPa for the carbon blend‐based ink, while the silver ink is measured around −10 MPa. The use of the membrane‐based method underlines the influence of exact deposition and curing conditions on the ink film material properties. The impact of the substrate on the ink layer properties, such as the thickness and its uniformity, is discussed, especially with regard to the heat treatment of the membrane.

Differential pressure sensors based on transfer-free piezoresistive layered PdSe2 thin films

Piezoresistive layered two-dimensional (2D) crystals offer intriguing promise as pressure sensors for microelectromechanical systems (MEMS) due to their remarkable strain-induced conductivity modulation. However, integration of the conventional chemical vapor deposition grown 2D thin films onto a micromachined silicon platform requires a complex transfer process, which degrades their strain-sensing performance. In this study, we present a differential pressure sensor built on a transfer-free piezoresistive PdSe2 polycrystalline film deposited on a SiN x membrane by plasma-enhanced selenization of a metal film at a temperature as low as 200 °C. Based on the resistance change and finite element strain analysis of the film under membrane deflection, we show that a 7.9 nm thick PdSe2 film has a gauge factor (GF) of −43.3, which is ten times larger than that of polycrystalline silicon. The large GF enables the development of a diaphragm pressure sensor with a high sensitivity of 3.9 × 10−4 kPa−1 within the differential pressure range of 0–60 kPa. In addition, the sensor with a Wheatstone bridge circuit achieves a high voltage sensitivity of 1.04 mV·kPa−1, a rapid response time of less than 97 ms, and small output voltage variation of 8.1 mV in the temperature range of 25 °C to 55 °C. This transfer-free and low-temperature grown PdSe2 piezoresistive thin film is promising for MEMS transducer devices.

High-throughput membrane deflection characterization of shape memory alloy thin films

Nickel–Titanium (Ni–Ti) shape memory alloy thin films are currently gaining significant attention for small-scale systems, but device integration is still challenging due to its high compositional-dependent behavior. Therefore, it is crucial to identify the optimal parameters required to fabricate desirable samples. In this study, combinatorial high-throughput membrane deflection experiments were performed to investigate the mechanical properties of submicron-thick Ni–Ti thin films. The mechanical properties of freestanding Ni–Ti thin films, sputter-deposited with compositions and thicknesses ranging from 45.7 at. % to 52.7 at. % nickel and 270–530 nm were evaluated. With an increase in the Ni content, the crystallinity and existing phases of the films varied and exhibited an overall increasing trend of elastic modulus, transformation stress, percentage of recoverable strain and hysteresis area. Based on the obtained results, the compositional ratio of Ni–Ti films can be tailored accordingly to meet the different requirements of small-scale devices, and to then extend the employment of this high-throughput methodology in exploring advanced metallic alloys and ceramic composites.

Vein-Membrane Interaction in Cambering of Flapping Insect Wings.

It is still unclear how elastic deformation of flapping insect wings caused by the aerodynamic pressure results in their significant cambering. In this study, we present that a vein-membrane interaction (VMI) can clarify this mechanical process. In order to investigate the VMI, we propose a numerical method that consists of (a) a shape simplification model wing that consists of a few beams and a rectangular shell structure as the structural essence of flapping insect wings for the VMI, and (b) a monolithic solution procedure for strongly coupled beam and shell structures with large deformation and large rotation to analyze the shape simplification model wing. We incorporate data from actual insects into the proposed numerical method for the VMI. In the numerical analysis, we demonstrate that the model wing can generate a camber equivalent to that of the actual insects. Hence, the VMI will be a mechanical basis of the cambering of flapping insect wings. Furthermore, we present the mechanical roles of the veins in cambering. The intermediate veins increase the out-of-plane deflection of the wing membrane due to the aerodynamic pressure in the central area of the wing, while they decrease it in the vicinity of the trailing edge. As a result, these veins create the significant camber. The torsional flexibility of the leading-edge veins increases the magnitude of cambering.

Additively Manufactured Porous Filling Pneumatic Network Actuator

This research project investigated the additive manufacturing of pneumatic actuators based on the principle of droplet dosing using an Arburg Freeformer 300-3X 3D printer. The developed structure consists of a porous inner filling and a dense, airtight chamber. By selectively varying the filling densities of the porous inner filling, different membrane deflections of the actuator were achieved. By linking the actuators, a pneumatic network actuator was developed that could be used in endorobotics. To describe the membrane deflection of an additively manufactured pneumatic actuator, a mathematical model was developed that takes into account the influence of additive manufacturing and porous filling. Using a dedicated test rig, the predicted behavior of the pneumatic actuators was shown to be qualitatively consistent. In addition, a pneumatic network actuator (PneuNet) with a diameter of 17 mm and a height of 76 mm, consisting of nine chambers with different filling densities, could be bent through 82° under a pressure of 8 bar. Our study shows that the variation of filling densities during production leads to different membrane deflections. The mathematical model developed provides satisfactory predictions, although the influence of additive manufacturing needs to be determined experimentally. Post-processing is still a necessary step to realize the full bending potential of these actuators, although challenges regarding air-tightness remain. Future research approaches include studying the deflection behavior of the chambers in multiple directions, investigating alternative materials, and optimizing the printing process to improve mechanical properties and reliability.

Influence of membrane deflection on energy exchanger performance

Influence of membrane deflection on energy exchanger performance

Accurate determination of stiffness and strength of graphene via AFM-based membrane deflection

The Young’s modulus and fracture strength of single and bilayer graphene (BLGr) grown by chemical vapour deposition (CVD) were determined using atomic force microscopy-based membrane deflection experiments. The uncertainty resulting from instrument calibration and the errors due to the experimental conditions like tip wear, loading position, and sample preparation were investigated to estimate the accuracy of the method. The theoretical estimation of the uncertainty on the Young’s modulus linked to the calibration is around 16%. Finite element simulations were performed to determine the effects of membrane shape and loading position on the extraction of the Young’s modulus. Off-centre loading results in the overestimation of the Young’s modulus while deviation from the circular shape leads to an underestimation of the stiffness. The simulated results were compared with experiments. With all these sources of errors taken into account, the Young’s modulus and fracture strength of CVD-grown single layer graphene are found equal to 0.88 ± 0.14 TPa and 134 ± 16 GPa, respectively. For CVD BLGr, the mean values of the Young’s modulus and fracture strength are equal to 0.70 ± 0.11 TPa and 95 ± 11 GPa, respectively.

A novel electromagnetic micropump with PDMS membrane supported by a stainless-steel microstructure

As a main component, membrane micropumps play a key role in developing microfluidic systems. This part pumps fluids by deflecting a membrane using a micro-actuator with a deflection range of a few micrometers during a few seconds. Most electromagnetic micropumps have low lifetime and fracture toughness or low recovery speed. Micropumps with metallic mass-spring structures can overcome the mentioned disadvantages or limitations. This study investigated the fabrication and characterization of a novel electromagnetic micropump. The proposed micropump consists of a stainless-steel mass-spring structure, a polydimethylsiloxane body and membrane, a permanent NdFeB magnet, a micro-coil, and a 3D printed spacer. To characterize the micropump, the effects of the frequency and duty cycle of the electric current applied to the micro-coil on the micropump flow rate and the membrane deflection vs. time were investigated. A membrane deflection of ±8 µm was obtained in 4 s by applying 1000 mA electrical current to the micro-coil. The maximum volumetric flow rate of 523 nl s−1 was obtained at a frequency of 125 mHz and a duty cycle of 50%. The von Mises stress distribution in the micropump membrane and variations of the fluid velocity in the microchannels were analyzed using the finite element method.

Mission Concept and Development of the First Interstellar CubeSat Powered by Solar Sailing Technology

Project Svarog is a student-led initiative aiming to reach the heliopause using a solar sail. Orbital models have proven the feasibility of the mission given the mass-to-area ratio of about 9 grams per square meter of the sail for a satellite launched on a piggyback mission to Mars. Solar sailing increases the flexibility of missions to the outer Solar System, as unique planet alignment, which was crucial for gravity assists is no longer required. Long-term missions require a better understanding of thin membrane behaviour since buckling of sail material under solar radiation pressure might cause the spacecraft to tumble unpredictably. Reduced order model of membrane deflection is thus coupled with orbital simulation, resulting in the determination of the operation regime, for which the mission escapes the Solar System. Additionally, vacuum chamber experiments designed to investigate the effects of solar radiation pressure and heating on the transient and steady-state behaviour of the sail have been devised. The system is designed to be built as a 6U CubeSat, being one of the first missions to utilise small-scale platforms for deep space missions. Granted that the first mission is successful, the Svarog system could also serve as a low-cost testbed for new technologies and research opportunities in deep space. Keywords: Satellite, Deep Space, CubeSat, Solar Sail, Orbital Mechanics, Structural Design

Drain current variation of extruded active area field-effect transistors on a silicon nitride membrane for low scale pressure of micro liter droplets

Extruded active area field-effect transistors (EA-FETs) with a silicon nitride membrane have been reported for low stress deflection sensing. EA-FETs have an extruded active area to improve the sensitivity of membrane deflection, whereas conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) typically have a rectangle active area. EA-FETs are connected on edge of a silicon nitride membrane produced by potassium hydroxide wet etch of micro electromechanical systems (MEMS) while EA-FETs have a fundamental structure and operation property of MOSFETs. Proposed EA-FETs with a silicon nitride membrane showed 15.4% response of drain current variation by 1.5 μL deionized water droplets at 9 gate voltage while standard active area FETs showed 13.7% response under the same conditions. In addition, EA-FETs could measure isolated stress applied to the membrane without any other chemical reaction since the silicon nitride membrane of EA-FETs measured target materials separately.

Fluid-Structure Interactions and Aeroacoustic coupling of Airfoil with Flexible Membrane(s)

In this paper, fluid-structure interactions of a NACA 0012 airfoil mounted with short flexible membrane(s) and its coupling effect on airfoil aeroacoustics are presented. A time-domain direct aeroacoustic simulation coupled with structural dynamics is carried out at a low Reynolds number of 50,000 to explore the aeroacoustic-structural interactions. Two different airfoil configurations based on single and dual membranes are analyzed. The membrane deflections and their impact on the flow field are characterized in wavenumber-frequency domain to analyze the structural dynamics due to flow unsteadiness within the laminar boundary layer and the resulting acoustic waves emanating from the airfoil trailing edge. A strong correlation between the membrane displacement and downstream propagating flow is observed for all configurations whereas the correlation is considerably weakened between the membrane displacement and upstream acoustic waves which ultimately results in the airfoil self-noise reduction without affecting the airfoil aerodynamics. The extent of noise reduction for dual membrane airfoil configuration is observed to be considerably higher than the single membrane airfoil configuration which corresponds to a much lower correlation among the upstream propagating acoustic waves and membrane deflection for both the membranes and redistribution of upstream flow energy into different frequencies.

An Improved Static Membrane Deflection Analysis for Collapse Mode CMUT Fabricated by Sacrificial Release Method

To improve the accuracy of the static membrane deflection calculation for the collapse mode capacitive micromachined ultrasonic transducer (CMUT) fabricated by sacrificial release (SR) method. The beam theory was used and the substrate supporting force can be modeled by a coefficient to the load on the membrane. The surrounding supporting post bending can be modeled by applying the elastic support boundary conditions (ESBCs) for the peripheral part of the membrane. CMUT devices have been fabricated using the SR process to validate this analytical analysis. Young’s modulus of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text {Si}_{{3}} \text {N}_{{4}}$ </tex-math></inline-formula> was derived as 200 GPa by a method using center deflections of several different radii single-layer conventional devices under 1 atm. The analytical deflection results and contact radius results for the collapse mode CMUT membranes were testified by experimental results under 1 atm and were found matching the experimental results. This showed that the analysis can provide improved results for SR fabricated CMUT devices by including the substrate supporting effect and the post bending effect.

Mechanical characterization of thin films via constant strain rate membrane deflection experiments

The mechanical behavior of freestanding metal thin films (gold, aluminum, and nickel-molybdenum-tungsten alloy) is characterized using micro-tensile testing and membrane deflection experiment (MDE). Micro-tensile and membrane samples are simultaneously fabricated on a single wafer to avoid microstructural differences. A constant strain rate MDE methodology is developed to directly compare each test method. Finite element analysis is performed to investigate potential sources of error in MDE. Specifically, the effects of in-plane and out-of-plane misalignment, tip blunting, sample dimension, and substrate deformation are studied, and physical insights gained from the analysis were applied to the experiments. By comparing with the micro-tensile tests, it is experimentally demonstrated that the stress-strain curve of freestanding metal thin films can be successfully measured via constant strain rate MDE. In particular, yield stress shows a good agreement with that obtained from micro-tensile tests, demonstrating the usefulness of applying the constant strain rate methodology in MDE testing. Furthermore, MDE enables residual stress measurements of the deposited films. Constant strain rate MDE developed in this study can serve as a useful technique for high-throughput measurement of in-plane mechanical properties of metal thin films.

Tuning the hydraulic resistance by swelling-induced buckling of membranes in high-aspect-ratio microfluidic devices.

Controlling fluid flow in microfluidic devices and adapting it to varying conditions by selectively regulating hydrodynamic properties is of critical importance, as the field of microfluidics faces increasingly complex challenges in its wide range of applications. One way to manipulate flows in microfluidic devices is to introduce elastic elements that can be actively or passively deformed. In this work, we developed a membrane-based microfluidic device that allows us to study the deformation of swollen thin membranes as a function of the volume fractions in binary mixtures - here isopropanol and water. Furthermore, the membrane deformation can be used to control pressure-driven flows within the device. The device consists of two microfluidic channels separated by a thin membrane that deforms by a buckling-based mechanism, when the isopropanol volume fraction of the solvent flowing through it exceeds a certain volume fraction. The buckling membrane causes a sinusoidal height variation in both adjacent channels, resulting in a large increase in hydraulic resistance. We show that buckling-based deflections of elastic membranes can be used to amplify small changes in the degree of swelling to produce large changes in the microchannel geometry of the device, sufficient to manipulate the flow rate of pressure-driven flows in the microdevice.