Flexible Diaphragm Research Articles

Fabrication and testing of PMOS current mirror-integrated MEMS pressure transducer

PurposeThis paper aims to describe the fabrication, packaging and testing of a resistive loadedp-channel metal-oxide-semiconductor field-effect transistor-based (MOSFET-based) current mirror-integrated pressure transducer.Design/methodology/approachUsing the concept of piezoresistive effect in a MOSFET, three identicalp-channel MOSFETs connected in current mirror configuration have been designed and fabricated using the standard polysilicon gate process and microelectromechanical system (MEMS) techniques for pressure sensing application. The channel length and width of thep-channel MOSFETs are 100 µm and 500 µm, respectively. The MOSFET M1 of the current mirror is the reference transistor that acts as the constant current source. MOSFETs M2 and M3 are the pressure-sensing transistors embedded on the diaphragm near the mid of fixed edge and at the center of the square diaphragm, respectively, to experience both the tensile and compressive stress developed due to externally applied input pressure. A flexible square diaphragm having a length of approximately 1,000 µm and thickness of 50 µm has been realized using deep-reactive ion etching of silicon on the backside of the wafer. Then, the fabricated sensor chip has been diced and mounted on a TO8 header for the testing with pressure.FindingsThe experimental result of the pressure sensor chip shows a sensitivity of approximately 0.2162 mV/psi (31.35 mV/MPa) for an input pressure of 0-100 psi. The output response shows a good linearity and very low-pressure hysteresis. In addition, the pressure-sensing structure has been simulated using the parameters of the fabricated pressure sensor and from the simulation result a pressure sensitivity of approximately 0.2283 mV/psi (33.11 mV/MPa) has been observed for input pressure ranging from 0 to 100 psi with a step size of 10 psi. The simulated and experimentally tested pressure sensitivities of the pressure sensor are in close agreement with each other.Originality/valueThis current mirror readout circuit-based MEMS pressure sensor is new and fully compatible to standard CMOS processes and has a promising application in the development CMOS-MEMS-integrated smart sensors.

Collapse shake-table testing of a clay-URM building with chimneys

This paper discusses the results of a unidirectional shake-table test carried out on a full-scale unreinforced clay-brick masonry building with chimneys. The specimen embodied construction details representative of old detached single-storey houses of the Groningen province in the Netherlands, without any specific seismic-resistant detailing. The house featured a typical Dutch gambrel roof that allowed for living space above the attic floor, with high gables that were vulnerable to out-of-plane excitation. The floor consisted of timber joists and planks, resulting in a flexible diaphragm. Two clay-brick chimneys were included to investigate the performance of falling non-structural masonry elements in earthquakes. A cumulative incremental dynamic test was performed up to collapse conditions, using input ground motions compatible with induced seismicity scenarios for the examined region. The paper summarises the key characteristics of the specimen and the observations from the shake-table tests, illustrating the evolution of the structural and non-structural damage, and the dynamic response of the building. The attainment of significant damage limit states is correlated with experimentally defined engineering demand parameters and ground-motion intensity measures for the performance-based seismic assessment of unreinforced masonry buildings. All data from the tests are available upon request on www.eucentre.it/nam-project.

STUDY OF PROCESS CONTROL ON PIEZOELECTRIC DROP-ON-DEMAND EJECTION

The size and uniformity of micro-droplets are key factors influencing the quality of the molded part by micro-droplet ejecting additive manufacturing technology. In this paper, a piezo-actuated micro-droplet ejection device for generating uniform micro-droplets is studied. The piezoelectric material drives the flexible diaphragm to vibrate and pushes the liquid out of the nozzle and produces micro-droplets. The amplitude of the diaphragm under different control parameters and its influence on the size and uniformity of the generated micro-droplets are investigated by numerical simulation and experiment. The results indicate that the amplitude of the diaphragm is affected by the driving voltage and the piezoelectric frequency and the experimental value of the diaphragm's center point amplitude is less than that of the theoretical calculation value which is mainly influenced by the piezoelectric frequency. The amplitude of the diaphragm will change the pressure inside the nozzle, which leads to the varied sizes of the micro-droplet. When the driving voltage is constant, the diaphragm has the maximum amplitude for the piezoelectric frequency at 10 Hz. As the amplitude of the diaphragm increases, droplets can be generated when the liquid velocity at the orifice and the length of the liquid column increase to a critical value. As the amplitude of the diaphragm continues to increase and the length of the liquid column at the orifice is beyond to a critical value, a satellite micro-droplet is formed. When the amplitude range of the membrane is between 30 $\mu $m and 42 $\mu $m, micro-droplets can be stably formed whose uniformity and size meet the demand well, and the minimum generating micro-droplets size is 339.8 $\mu $m. The maximum change rate of droplet diameter and adjacent two droplets are 0.29% and 2.67% respectively. Results are benefit to promote the uniformity of micro-droplets and will provide a reference for the development of piezoelectric droplet ejection devices.

Characterization of Impingement Heat/Mass Transfer to the Synthetic Jet Generated by a Biomimetic Actuator

Two biomimetic synthetic jet (SJ) actuators were designed, manufactured, and tested under conditions of a jet impingement onto a wall. Nozzles of the actuators were formed by a flexible diaphragm rim, the working fluid was air, and the operating frequencies were chosen near the resonance at 65 Hz and 69 Hz. Four experimental methods were used: phase-locked visualization of the oscillating nozzle lips, jet momentum flux measurement using a precision scale, hot-wire anemometry, and mass transfer measurement using the naphthalene sublimation technique. The results demonstrated possibilities of the proposed actuators to cause a desired heat/mass transfer distribution on the exposed wall. It was concluded that the heat/mass transfer rate was commensurable with a conventional continuous impinging jets (IJs) at the same Reynolds numbers.

A Synthetic Jet Issuing From a Bio-Inspired Actuator With an Oscillating Nozzle Lip

A novel variant of a synthetic jet actuator (SJA) has been designed, manufactured, and tested. The novelty consists in a bio-inspired nozzle whose oscillating lip is formed by a flexible diaphragm rim. The working fluid is air, and the operating frequency is 65 Hz. The proposed SJA was tested by three experimental methods: phase-locked visualization of the nozzle lips, hot-wire anemometry, and momentum flux measurement using a precision scale. The results demonstrate advantages of the proposed SJA, namely, an increase in the momentum flux by 18% compared with that of a conventional SJA.

Experimental Research on Fluid Coupling Flexible Actuator.

In the field of micromechanics, piezoelectric actuator has attracted great attention for its high-frequency response, high displacement resolution, and high output force. However, its prospect of practical application has been largely limited by the displacement of micrometer. A fluid coupling flexible actuator was proposed, which utilizes resonance to enlarge the output displacement. The actuator uses a piezoelectric oscillator as an excitation source, fluid as the transmission medium and a flexible diaphragm for the displacement output. On the condition that the fluid is inviscid and incompressible, mathematical formulation of the membrane vibration theory has been analyzed. Then, the prototype is made. The displacement is amplified 21 times to 1.106 mm when driving frequency is 127 Hz. The flexible diaphragm appears the largest displacement output when driving frequency is close to one of the system’s natural frequency. Then, the points with zero amplitude form a circle on the surface of flexible diaphragm and the movement direction of the flexible diaphragm is opposite on different sides of the circle. In fact, rather than vibrates at the first resonance frequency, the membrane in the essay is vibrating at a certain higher-order resonance frequency. The experimental results are mainly consistent with the theoretical analysis.

Experimental seismic performance of a full-scale unreinforced clay-masonry building with flexible timber diaphragms

This paper presents the results of a unidirectional shake-table test performed on a full-scale, single-storey unreinforced masonry building. The specimen represented a typical detached house of the Groningen region of the Netherlands, consisting of double-wythe clay-brick unreinforced masonry walls, without any specific seismic detailing. The building prototype included large openings and a reentrant corner, causing a discontinuity in one of the perimeter walls. The floor was made of timber beams and planks, resulting in a flexible diaphragm. The roof, characterized by a very steep pitch, consisted of a series of timber trusses connected by wood purlins and boards. The two façades perpendicular to the shaking direction were designed to represent two typical gable geometries. An incremental dynamic test was conducted up to the near-collapse state of the specimen, using input ground motions compatible with induced-seismicity scenarios for the examined region. This paper summarizes the main characteristics of the specimen and the shake-table experimental results, illustrating the dynamic response of the structure, the evolution of the damage mechanisms, and the attainment of significant limit states.

A novel flexible planar loudspeaker with coils on polyimide diaphragm

This paper presented a low cost flexible electro-dynamic planar loudspeaker (FEPL) with coils on polyimide diaphragm. The structure was very simple to put a flexible thin film diaphragm (electroplated traces of copper coil) above a flexible magnetic (placed in the bottom of cavity), thus forming an integration of electromagnetic actuation and planar flexible structure. The advantages are as follows: (1) the new loudspeaker became a flat flexible one, which could not only directly drive the vibration film to increase the power efficiency, but reduce the total harmonic distortion (THD). (2) It could be used as flexible electronics and easily deployed on the surface of any object with magnetic property or using adhesive transfer tapes. To optimize the performance of sound pressure level (SPLs), this study made detailed analyses on the thickness of cavity, turns of coil, magnet polarization, and diaphragm dimension. Noted as the cavity height increasing, the magnetic flux densities of both vertically and horizontally polarized magnet were decreased. But they were nearly constant over the surface with the same height for the vertically polarized magnet. On the other hand, as the cavity height of the horizontally polarized magnet increased, the magnetic flux densities would be decreased rapidly at the locations moving farther away from the center point. Several kinds of planar-type loudspeakers for the coils wounded in spiral-in, spiral-in and spiral-out, and zigzag shapes and plated with copper and aluminum were applied for performance tests, and the comparisons with the traditional cone-type loudspeaker were also made. Finally, the sound pressure levels (SPLs) were compared for three rectangular coils with different dimensions and number of turns. These effects were not discussed in previous literature of study.

Seismic Response of Plan‐Asymmetric Structures with Diaphragm Flexibility

The seismic behavior of asymmetric structures with a flexible diaphragm was studied by conducting inelastic dynamic time‐history analyses. Asymmetric structures with different configurations of mass, stiffness, and strength centers, in combination with a wide range of diaphragm flexibility, were evaluated. The behavior of structures was studied by considering three aspects: (1) effect of structural asymmetry on diaphragms deformation; (2) effect of diaphragm flexibility on demands of the lateral load‐resisting elements; (3) optimum configuration of mass, stiffness, and strength centers to limit important engineering demand parameters in asymmetric structures with a flexible diaphragm. The results showed that the shear‐dominant deformation of diaphragms is sensitive to both structure asymmetry specifications and the degree of diaphragm flexibility; therefore, it can be used for the qualitative classification of the seismic behavior of structures. Also, the center of strength in structures with flexible diaphragm is more important relative to the stiffness center and has a significant effect on engineering demands at all levels of diaphragm flexibility. Moreover, it was found that a suitable configuration of centers in torsionally stiff structures depends on the degree of diaphragm flexibility, in addition to the intensity of earthquakes (structure yield level) and selected engineering demand parameter.

Structural Engineering by way of BIM

BIM idea is increasing the productivity of work. Multidimensional solutions implemented in BIM systems not only allow many structural calculations, but also access the better scheduling, cost estimating, visualizations. In some cases both software and hardware can be a bottleneck. To create an interaction between BIM philosophy and practice of the structural design the experimental research has tested eight structural systems of the high-rise building by way of Building Information Modelling. Multiple variants of the two main bracing system types: (i) a spatial truss and (ii) a spatial shell bracing system. In every model there was checked influence of slab model: with slabs meeting the conditions of a rigid plate (flexible diaphragm slab) and with slabs with no additional stiffening (shell slab). The ULS and SLS requirements were analysed for elements and superstructure. In addition, selected issues concerning scheduling of works (4D BIM) and cost estimating (5D BIM) were discussed with the extensive 3D model developed in line with the BIM standards. Rapid prototyping has enabled to realize the behaviour of structural systems. The outputs of this study are presented in the paper.

Wearable Devices: Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring (Adv. Mater. 39/2017)

A flexible microfluidic diaphragm pressure sensor using liquid-metal microchannels is presented by Ali Javey and co-workers in article number 1701985. The sensor is capable of detecting pressures less than 100 Pa with a resolution of less than 50 Pa. Both heart-rate monitoring and tactile pressure mapping of a glove with multiple embedded sensors are demonstrated.

Modeling the future of irrigation: A parametric description of pressure compensating drip irrigation emitter performance.

Drip irrigation is a means of distributing the exact amount of water a plant needs by dripping water directly onto the root zone. It can produce up to 90% more crops than rain-fed irrigation, and reduce water consumption by 70% compared to conventional flood irrigation. Drip irrigation may enable millions of poor farmers to rise out of poverty by growing more and higher value crops, while not contributing to overconsumption of water. Achieving this impact will require broadening the engineering knowledge required to design new, low-cost, low-power drip irrigation technology, particularly for poor, off-grid communities in developing countries. For more than 50 years, pressure compensating (PC) drip emitters—which can maintain a constant flow rate under variations in pressure, to ensure uniform water distribution on a field—have been designed and optimized empirically. This study presents a parametric model that describes the fluid and solid mechanics that govern the behavior of a common PC emitter architecture, which uses a flexible diaphragm to limit flow. The model was validated by testing nine prototypes with geometric variations, all of which matched predicted performance to within R2 = 0.85. This parametric model will enable irrigation engineers to design new drip emitters with attributes that improve performance and lower cost, which will promote the use of drip irrigation throughout the world.

Effects of an additional air chamber on the sensitivity of a capacitive pressure sensor

This study demonstrates the effect of an additional air chamber on the sensitivity of an air-sealed capacitive pressure sensor. This effect is investigated by theoretical analysis, finite element analysis, and experimental validation. First, the variation in sensitivity of the capacitive pressure sensor with air chambers of various volumes was investigated by an analytical method as a theoretical approach and by FEM simulation. The results showed that the sensitivity of an air-sealed capacitive pressure sensor with a flexible diaphragm could be enhanced by adopting an additional air chamber. In this process, the variation in the ambient temperature was also considered. Experimental validation was conducted by fabricating a sensor to consider the previous result. The results of the experimental validation of the air-sealed capacitive pressure sensor with natural rubber latex (NRL) diaphragm showed that the sensitivity increased more than 15-fold by adopting the additional air chamber compared to the NRL sensor without the air chamber. Consequently, the NRL sensor with the additional air chamber measured a pressure sensitivity of 8986 ppm/kPa and a pressure responsivity of 1.391 MHz/kPa in the applied pressure range of 1–10 kPa. Finally, the effect of the variation in ambient temperature on the sensitivity of an air-sealed capacitive pressure sensor was measured and compared with the theoretical and FEM simulation results.

ProTEK PSB as Biotechnology Photosensitive Protection Mask on 3C-SiC-on-Si in MEMS Sensor

This project presents the fabrication of MEMS employing a cubic silicon carbide (3C- SiC) on silicon wafer using newly developed ProTEK PSB as biotechnology photosensitive protection mask. This new biotechnology can reduce the number of processes and simplify the process flow with minimal impact on overall undercut performance. The 680 pm thick wafer is back-etched, leaving the 3C-SiC thin film with a thickness of 1.0 μm as the flexible diaphragm to detect pressure. The effect of the new coating of ProTEK PSB on different KOH solvents were investigated depending on various factors such as development time, final cure temperature and the thickness of the ProTEK PSB deposited layer. It is found that 6.174 μm thickness of ProTEK PSB offers some possibility of reducing the processing time compared to silicon nitride etch masks in KOH (55%wt, 80°C). The new ProTEK PSB biotechnology photosensitive protection mask indicates good stability and sustains its performance in different treatments under KOH and IPA for 8 hours. This work also revealed that the fabrication of MEMS sensors using the new biotechnology photosensitive protection mask provides a simple assembly approach and reduces manufacturing costs. The MEMS sensor can operate up to 500 °C as indicated under the sensitivity of 0.826 pF/MPa with nonlinearity and hysteresis of 0.61% and 3.13%, respectively.

An Innovative Spool-Type Pressure Feedback Restrictor for Hydrostatic Bearings

This study presents the design of a novel single-acting spool-type pressure feedback restrictor for hydrostatic bearings. The increasing demand for larger machine tools that will handle heavy loads with precision has resulted in much attention being directed toward the development of hydrostatic bearings. At present, the most commonly used pressure feedback restrictor for hydrostatic bearings employs a membrane. In the membrane device, a flexible metal diaphragm is the key component and this kind of restrictor can provide precise metering of hydraulic oil flow. However, the membrane device is not suitable for extremely heavy loads and we present a spool type of pressure feedback restrictor as an alternative. This type of restrictor can support much heavier loads than the membrane type and is suitable for the bearings in large machine tools. The novel design has two significant features: the first is the orifice restrictor which effectively circumvents the influence of fluctuating oil temperature. The second feature is the introduction of adjustment screws at each end of the valve body which widen the range of operation. A prototype was successfully fabricated and the experimental results validate the design of this new and innovative pressure feedback restrictor.

Consideration of diaphragm flexibility in the seismic design of one-story buildings

The response of single-story buildings with a flexible roof diaphragm to earthquake excitations is strongly influenced by the flexibility of the diaphragm. Diaphragm flexibility increases the period of the building, magnifies the ductility demand on the lateral load resisting system, and changes the manner in which the inertia forces are distributed along the length of the diaphragm, which leads to a magnification of the internal forces in the diaphragm. An analytical study is carried out to examine the influences of diaphragm flexibility on the seismic response of one-story buildings. The magnification in bending moment and shear force is investigated. An alternative approach to the seismic design of one-story buildings with flexible diaphragms is studied. In such approach, the diaphragm is designed to act as the energy dissipating system while the braces are designed to remain elastic. The effects of the nonlinearity of the diaphragm on the seismic response of the system are examined and methods are proposed to account for the structural implications associated with designing the diaphragm to act as the energy dissipating system.

Evaluation of an alternative seismic design approach for rigid wall flexible wood roof diaphragm buildings through probabilistic loss estimation and disaggregation

Rigid Wall Flexible roof Diaphragm (RWFD) buildings, commonly referred to as “big-box” buildings are the most prevalent type of construction for low-rise industrial and warehouse facilities in the United States (US). These buildings usually incorporate rigid-in plane concrete tilt-up walls and flexible wood roof diaphragms, which is a commonly seen construction technique in the Western United States. Due to their vulnerability in high seismic areas (e.g. California) observed in past earthquakes, an alternative design methodology was introduced in the FEMA P1026 document to account for the response of the flexible roof diaphragm. The FEMA P1026 design approach has been validated through numerical collapse assessment studies. In this study, the Performance-Based Earthquake Engineering framework, introduced by the Pacific Earthquake Engineering Research (PEER) center, is combined with Monte Carlo Simulation to evaluate, in a probabilistic sense, the earthquake-induced economic losses for these structures. The results are presented in terms of expected losses for two hazard intensities: Maximum Considered Earthquake (MCE) and Design Earthquake (DE), while loss disaggregation plots for collapse and no-collapse losses are also presented. The results demonstrate the ability of the FEMA P1026 design approach to reduce earthquake losses compared to current code-conforming RWFD buildings. Additionally, the results can provide damage and loss information for modeling of these types of buildings within a resilient community and other spatially focused analyses.

Timber–Reinforced Concrete Core Hybrid System: Shake Table Experimental Test

AbstractThe law to promote the use of wood in the construction industry was announced by the Japanese government in 2010. As a result of this initiative, timber and timber-based hybrid buildings are increasingly used in public buildings. As the buildings are located in high seismic zone areas, however, validation of the current design guideline was of paramount importance. This paper reports the design and a shake table test of timber frame–reinforced concrete (RC) core hybrid systems. Three specimens (S1, S2, and S3) are tested: S1 and S2 are both one-story buildings with a nailed plywood floor (flexible diaphragm) and a rigid RC floor (rigid diaphragm), respectively. S3 is a two-story building with a nailed plywood floor. Each specimen is tested with increasing magnitude of earthquake loading. The shake table test results showed that the adopted design guideline is sufficient. At higher seismic loads, however, the prevalent plan irregularity induced higher torsional demand damage at the RC core and timb...

Direct displacement based seismic design for timber flexible diaphragms in masonry shear wall buildings

A method for analyzing the seismic performance of timber flexible diaphragms based on the direct displacement based seismic design (DDBD) principles has been developed. The method utilizes knowledge of timber diaphragm seismic behavior, such as natural period calculation, force–displacement and ductility–damping relationships, developed previously by the authors. Accuracy of the method is illustrated through analysis of four prototype buildings and comparison to recorded data and numerical results. All four prototype buildings have timber diaphragms in conjunction with either reinforced or unreinforced masonry shear walls. Excellent agreement is found between the results from the proposed DDBD approach, and those from both the recorded data and finite element analysis. The proposed method provides a rational and consistent design methodology for flexible diaphragm buildings, which is lacking in ASCE-7.

Sensitivity-Enhanced <inline-formula> <tex-math notation="LaTeX">$LC$ </tex-math> </inline-formula> Pressure Sensor for Wireless Bladder Pressure Monitoring

This paper presents a sensitivity-enhanced wireless passive $LC$ pressure sensor for monitoring bladder pressure, which can be minimally invasive implanted in the bladder or integrated to a commercial urinary catheter and avoid battery lifetime problem. The proposed sensor design and the theoretical model are useful to increase the pressure sensitivity of a typical air-sealed capacitive pressure sensor, particularly having a flexible diaphragm. The test results of an in vitro evaluation of the prototype $LC$ pressure sensor show a pressure sensitivity of 6385 ppm/kPa (a pressure responsivity of 1.215 MHz/kPa) before encapsulation coating in air at room temperature, whereas 4175 ppm/kPa (0.627 MHz/kPa) and 2679 ppm/kPa (0.304 MHz/kPa) after coating with silicone rubber in air and in water operation, respectively. Finally, the feasibility of the developed sensor is investigated through an animal test and confirmed by comparing with the data of conventional cystometry.