Flexible Diaphragm Research Articles

OS091. The origin of preeclampsia in diet-induced maternal endothelial stiffness

Despite research documenting variances in cellular hypoxia, angiogenesis, oxidative stress, endothelial signaling, and autoimmunity, the etiology of preeclampsia remains unknown. Women affected by preeclampsia show increased arterial stiffness and abnormal serum lipids when compared to unaffected mothers. Although enzymes modify and synthesize lipids, most acyl chains are incorporated into cell membranes unmodified from the form in which they were absorbed from the gastrointestinal tract. Therefore, diet plays a major role in determining the rheology and composition of cell membranes. A-To present a model of how diet might alter cell membrane composition and cause increased maternal membrane viscosity when lipids are actively transported across the placenta to the fetus. B-To demonstrate how rapidly changing maternal membrane composition and viscosity might cause the pathological elements of preeclampsia. Literature search. Compared to diets of 10,000 years ago, modern diets have increased trans- and long-chain fatty acids, elevated omega-6 to -3 fatty acid ratios, and produce stiffer cell membranes, therefore might require increased membrane softening components such as cis-polyunsaturated fatty acids (PUFA) to maintain homeoviscosity. High fetal requirements for essential PUFAs might deplete body stores of these molecules in mothers with decreased dietary intake, thereby causing increased maternal membrane stiffness. Native proteins are only marginally stable under physiological conditions. A 2005 study using artificial membranes and the receptor rhodopsin, demonstrated that alteration of membrane lipid composition to increase membrane stiffness caused lower rhodopsin activation [1]. Increased membrane stiffness arising from dietary lipid variances might alter membrane proteins and cause the endothelial signaling dysfunction of preeclampsia. Although primary amino acid sequences remain unchanged, the disruption of tertiary protein structure might yield proteins that appear foreign and thus evoke an immune response, giving rise to antibodies such as agonistic autoantibody angiotensin-1. In mitochondria, disruption of electron transport protein structures might interfere with electron tunneling and increase the production of free radicals and oxidative stress. Because oxygen diffuses more rapidly through flexible versus stiff membranes,stiff cell membranes might initiate the signaling cascade indicative of cellular hypoxia in preeclampsia with increased hypoxia inducible factor and angiogenic factors such as soluble endoglin and fms-like tyrosine kinase. The arterial intima acts as a sensor with blood pressure homeostatic responses modulated by the flexibility of endothelial membranes. Similarly to a diaphragm pressure transducer, if the diaphragm material is stiff, the signal is attenuated; conversely, a flexible diaphragm makes the instrument more sensitive to pressure. Thus, stiffened endothelium might cause hypertension. This paper presents a unifying molecular and cell membrane-based model of how diet-induced maternal cell membrane stiffness offers a coherent and unifying explanation for the pathological changes seen in preeclampsia.

ELECTROSTATIC LOUDSPEAKER CAPABLE OF DISPERSING SOUND BOTH HORIZONTALLY AND VERTICALLY

An electrostatic loudspeaker (ESL) assembly providing curvature in two directions for improved dispersion of sound waves. The ESL comprises at least one stator panel, a flexible diaphragm and a spacer that impedes contact between the stator panel and the diaphragm. The stator is formed from a material that comprises an array of apertures. Furthermore, the material can be annealed. The material temper, along with the aperture geometry and patter, affect the stretchability of the material. The two-axis curved structure enables a compact form of ESL to be realized, including bookshelf type loudspeakers whereas all known commercial units are comparable in height to that of a human listener. The individual curved ESL panels can also be readily combined to create larger transducer assemblies including omni-directional units.

スパンごとに区切られた非剛床をもつ木質構造の自由度縮約と地震応答評価法

スパンごとに区切られた非剛床をもつ木質構造の自由度縮約と地震応答評価法

Wafer back pressure control and optimization in the CMP process

Chemical mechanical polishing (CMP) is the most effective wafer global planarization technology. The CMP polishing head is one of the most important components, and zone back pressure control technology is used to design a new generation of polishing head. The quality of polishing not only depends on slurry, but also depends on the precise control of polishing pressures. During the CMP polishing process, the set pressure of each chamber is usually not the same and the presence of a flexible elastic diaphragm causes coupling effects. Because of the coupling effects, the identification of multi-chambers and pressure controls becomes complicated. To solve the coupling problem, this paper presents a new method of multi-chamber decoupled control, and then system identification and control parameter tuning are carried out based on the method. Finally, experiments of multi-chambers inflated at the same time are performed. The experimental results show that the presented decoupling control method is feasible and correct.

Micromachined flexible diaphragm backed PZT ultrasonic transducer with a controllable self-focused acoustic beam

This paper presents novel self-focused ultrasonic transducers batch-produced by microfabrication. A PZT film, tens of microns thick, can be deposited on an engineered flexible substrate composed of an F-number controllable parylene shaped diaphragm and heat resistant RTV material, with no fractures after thermal annealing. The residual stress of the PZT film is released through the curvature change of the fabricated parylene/RTV, spherically shaped diaphragm. The experimental relationship between the designed and resultant F-number of the fabricated transducer is discussed. The shaped PZT electromechanical coupling coefficient kt is determined as 0.41. A pulse-echo experiment is performed directly using the parylene/RTV curved diaphragm as the backing of the device. The outcome displays a central frequency of 50 MHz and a −6 dB bandwidth of 30% as well as a lateral resolution of 40 µm. An experiment for measuring the averaged acoustic intensity generated by the transducer in air is designed and tested. The result shows a maximum value of 43 µW mm−2 at the focus when the transducer is driven by an 11 MHz continuous sinusoidal wave of 3 Vpp.

Modelling of parametric excitation of a flexible coupling–rotor system due to misalignment

A flexible diaphragm coupling, connecting two rotating shafts, is investigated for its dynamic characteristics, when subjected to parallel offset misalignment. The diaphragm coupling is a constant velocity coupling which becomes asymmetric once misaligned. Asymmetry creates directional difference or spatial variation of stiffness, as shown by a quasi-static finite element (FE) analysis using ABAQUS software. As the shafts rotate, this spatial variation in stiffness makes the diaphragm coupling–rotor system model to become time-varying. The time-varying direct and cross–coupled stiffness terms of the coupling are synthesized from the FE model and used in the governing equations of motion of the coupling–rotor system. This leads to a parametrically excited system due to the time-periodic stiffness coefficients of the coupling. Using Simulink, numerical integration has been performed to find the response of the system for both mass unbalance and inclination unbalance excitations that arise due to the tilt of the principal axes of the diaphragm due to parallel misalignment. The responses obtained clearly indicate the effect of parametric excitation at one-fourth, one-third, and one-half of the principal parametric resonance. To verify this model, an experimental setup has been developed for the coupling–rotor system model with misalignment. The experimental results clearly show the asymmetry between the two lateral direction responses, as predicted by the model.

Design and fabrication of implantable pressure sensing resistor sensor for human bladder monitoring system

Many aging people and patients have difficulties in bladder control. Recent methods have been studied for non-invasive measuring for bladder information. It must be improved to a more convenient and real time measurable system for accurately analyzing and controlling individual bladder information. This paper presents the pressure sensor for the invasive bladder monitoring system. The system has the pressure sensing resistor sensor (PSRS) which is set-up inside the bladder. The PSRS consists of a flexible and contactable diaphragm which deforms towards an underlying substrate while a range of pressure is applied. The flexible diaphragm has a thin metal film which acts as a switch and the underlying substrate has interdigitated electrodes which serve as a variable resistor. The PSRS initially exhibits infinite electrical resistance with no external pressure applied since the metal switch is not contact with the interdigitated electrodes. As the applied pressure increases above a threshold, the contact area increases thus the resistance of the PSRS decreases. Based on the finite element analysis, proper ranges for the diaphragm size and gap distance are determined. The sensor, the diaphragm size of which is 2.6 × 2.6 mm2, has been fabricated through MEMS technology. The change of the electrical resistance is 0.5 Ω for the range of human bladder pressure (0–10 kPa). This PSRS will be effectively used for reliability and stability of the research for the improvement of bladder management. It can also be utilized for the future application.

Coupled Electrostatic-Structures-Fluidic Analysis of a Nozzle/Diffuser Diaphragm Micropump

Micropump is the key component in the micro total analytical system. The major technical impediment in improving the performance of this micro-device lies in the lack of understanding the physical phenomena and their interactions of electric, mechanical, and fluidic fields for performing their intended functions. Because of the complexity of the micropump, the full coupled numerical analysis is extremely needed. This paper presents for the results of such fully coupled simulations. CFDRC® was used for the transient analysis of an electrostatically actuated micropump. The results show that the dynamic characteristics of fluid in the micropump and the vibration of flexible diaphragm are highly interactive each other. The flow rectification of the nozzle/diffuser will work only after the pressure difference between the two ends of valve have reached at a critical value. In the pump chamber, the fluidic press distribution almost independent of the space variation. Due to the increasing demands for accuracy, the nonlinear features of viscous loss of the fluid can no longer be neglected or simplified, but have to be taken into account in detail.

Diffuser Micropump Structured with Extremely Flexible Diaphragm of 2-µm-thick Polyimide Film

Diffuser Micropump Structured with Extremely Flexible Diaphragm of 2-µm-thick Polyimide Film

Diffuser Micropump Structured with Extremely Flexible Diaphragm of 2-µm-thick Polyimide Film

A miniaturized diffuser/nozzle micropump with extremely thin (only 2.1 µm in thickness) polyimide (PI) membranes was fabricated on a 60-µm-thick Si wafer using simple photolithography processes. The diameter of the diaphragm was 2 mm, and the chamber depth was 60 µm. The micropump was functioned by deforming the membranes with alternating air pressure. The ethanol flow rate of the micropump was over 400 nl/min at 2.5 Hz with an actuated pressure of 5 kPa. The measured flow rate was relatively higher than those of previously reported micropumps with a similar chamber volume owing to the large deflection (over 40 µm) of the PI membrane. The micropump processing issues of plasma induced damage to the PI membrane during Si chamber etching and the behaviors of the static and dynamic deflections of the PI membrane was also discussed. On the basis of the advantages of photolithography processes and the good performance of the micropump, it is expected that the micropump can be fabricated on silicon integrated circuit chips.

Variable Alignment Loudspeaker System

A loudspeaker system has a primary driver and an active radiator sealed in an enclosure where the active radiator is adapted to vary its operating characteristics to tune the sound pressure level and resultant frequency response generated by a primary driver. The primary driver and the active radiator share the same acoustic volume of the enclosure, i.e., the primary driver and the active radiator share a common acoustic compliance of the internal enclosure volume. The primary driver has electromagnetic components designed to oscillate a flexible cone or diaphragm along the longitudinal axis of the primary driver. The active radiator has electromagnetic components adapted to couple to a number of electrical configuration settings. Each electrical configuration setting may affect the operating characteristics of the diaphragm of the active radiator and is reflected back electro-acoustically, through the shared volume, to the primary driver. This electro-acoustical coupling, in turn provides the tuning mechanism for the primary driver.

Wideband piezoelectric rectangular loudspeakers using a tuck shaped PVDF bimorph

Piezoelectric loudspeakers are characterized by their very simple structure, however, their sound radiation performance in the low frequency region is poor because their diaphragms are too stiff for large amplitude vibration. In this paper the authors propose an innovative method for improvement of the low frequency radiation performance of piezoelectric direct-radiator loudspeakers. This method involves using a flat-boxy loudspeaker unit with a pleated tuck-shape flexible diaphragm formed of a laminated sheet of PVDF (polyvinylidenfluoride) piezoelectric film. In this paper an explanation of the proposed loudspeaker unit construction is followed by theoretical analysis. Then a few experimental results are shown. Finally a practical multi-way loudspeaker system with satisfactorily wide frequency range for music is constructed by combination of a few loudspeaker units.

Dual-mode operation of flexible piezoelectric polymer diaphragm for intracranial pressure measurement

The dual-mode operation of a polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) piezoelectric polymer diaphragm, in a capacitive or resonant mode, is reported as a flexible intracranial pressure (ICP) sensor. The pressure sensor using a capacitive mode exhibits a higher linearity and less power consumption than resonant mode operated pressure sensor. In contrast, the latter provides better sensitivity and easier adaption for wireless application. The metrological properties of the dual-mode ICP sensor being described are satisfactory in vitro. We propose that the piezoelectric polymer diaphragm has a promising future in intracranial pressure monitoring.

CALCULATION METHOD FOR ECCENTRICITY AND CORRECTION COEFFICIENT OF TORSIONAL ON CONSIDERATION WITH FLEXIBLE HORIZONTAL DIAPHRAGM

The current earthquake resistant design code for building in Japan, basically assumed a rigid horizontal diaphragm while calculating the eccentricity and correction coefficient of torsion. Such assumption may cause dangerous design while considering a flexible horizontal diaphragm with large eccentricity for real structure. Considering the shear deformation of floor, calculation method has been presented in this paper for eccentricity and correction coefficient of torsion. In elastic design, eccentric moment caused by earthquake force is generally resisted by the walls both X and Y directions, which in such case show rotation resist effect. Assuming the shear stiffness of the floor and the rotational resistant force from the wall to be in-series, formulae for calculating the eccentricity have been derived. These formulae also are verified by simulating an elastic one span model, using both static analyses and dynamic time history analyses.

Evaluation and control of the in-plane stiffness of timber floors for the performance-based retrofit of URM buildings

The seismic response of existing un-reinforced masonry (URM) buildings is strongly dependent on the characteristics of wooden floors and, in particular, on their in-plane stiffness and on the quality of connection between the floors and the URM elements. It is generally well-recognized that an adequate in-plane-stiffness and proper connections can significantly improve the three-dimensional response of these buildings, obtaining a better distribution and transfer of forces to the lateral load resisting walls. However, the extensive damage observed during past earthquakes on URM buildings of different types have highlighted serious shortcomings in typical retrofit interventions adopted in the past and based on stiffening the diaphragm. Recent numerical investigations have also confirmed that increasing the stiffness of the diaphragm is not necessarily going to lead to an improved response, but could actually result to detrimental effects. The evaluation of the in-plane stiffness of timber floors in their as-built and retrofitted configuration is still an open question and a delicate issue, with design guidelines and previous research results providing incomplete and sometimes controversial suggestions to practicing engineers involved in the assessment and/or retrofit of these type of structures. In this contribution, the role of the in-plane stiffness of timber floors in the seismic response of URM buildings is critically discussed, based on the relatively limited available experimental and numerical evidences. A framework for a performance-based assessment and retrofit strategy of URM buildings, capable of accounting for the effects of a flexible diaphragm on the response prior to and after the retrofit intervention, is then proposed. By controlling the in-plane stiffness of the diaphragm, adopting a specific strengthening (or weakening) intervention, the displacements, accelerations and internal force demands can be maintained within targeted levels. This will protect undesired local mechanisms and aim for a more appropriate hierarchy of strength within the whole system.

Design of a high sensitivity FET integrated MEMS microphone

FET based MEMS microphones comprise of a flexible diaphragm that works as the moving gate of the transistor. The integrated electromechanical transducer can be made more sensitive to external sound pressure either by increasing the mechanical or the electrical sensitivities. We propose a method of increasing the overall sensitivity of the microphone by increasing its electrical sensitivity. The proposed microphone uses the transistor biased in the sub-threshold region where the drain current depends exponentially on the difference between the gate-to-source voltage and the threshold voltage. The device is made more sensitive without adding any complexity in the mechanical design of the diaphragm.

Design, analysis and optimization of an electromagnetic actuator for a micro impedance pump

This study designs and optimizes an electromagnetic actuator for use in a valveless micro impedance pump. The actuator is modeled to have an electroplated permanent magnet mounted on a flexible PDMS diaphragm and a planar copper micro-coil patterned on a bottom glass substrate. The constituent parts of the actuator, namely the diaphragm, the micro-coil and the magnet, are modeled, analyzed and optimized in such a way as to maximize the actuating force while simultaneously ensuring the mechanical integrity of the device. In performing the analyses, theoretical and mathematical models of the stroke volume and diaphragm deflection are developed based on thin plate theory. The design models are verified theoretically and numerically, and the relationships between the electromagnetic force, the diaphragm displacement and the diaphragm strength are systematically explored. Overall, the results reveal that in the optimized device, the target diaphragm deflection of 20 µm can be obtained using a compression force of 12 µN developed by a micro-coil input current of 0.8 A. The electromagnetic actuator proposed in this study provides an ideal solution for the pumping requirements of a variety of biomedical chips and microfluidic applications and therefore represents a valuable contribution to the ongoing development of lab-on-a-chip systems.

Dynamics of a Class of Horizontal Setback Buildings with Flexible Floor Diaphragm

This technical note presents a convenient modeling/design procedure for a class horizontal setback building to minimize the adverse effect of in-plane floor flexibility. Existence of such a class requires proportional eigenvalue problems of all the constituting frames regardless of the floor properties. For L, T, + etc. shape of buildings, the eigenvalue problem (of the frames) along two orthogonal directions need not be proportional. Moreover, the presence of a nonrectangular joint region theoretically precludes the existence of such a class. A step-by-step proportioning procedure, in the presence of a nonrectangular joint region, is outlined such that (1) “nearly” rigid floor modes exist, and (2) participation of the flexible floor modes under spatially uniform ground motion is close to zero.

Dc superconducting quantum interference device based neodymium magnet displacement sensor for superfluid experiments

A new displacement sensor that uses a rare-earth magnet attached to a flexible diaphragm is demonstrated for superfluid experiments. Its construction, calibration, and performance are described.

Auto-focusing actuator and camera module including flexible diaphragm for mobile phone camera and wireless capsule endoscope

Recent cellular phones have high-resolution, compact digital camera modules that have several millions of pixels. Although being small, such several mega-pixel camera modules definitely need to be able to execute auto-focusing and/or optical zooming in order to obtain precise images. Hence, image photographing devices having driving mechanisms that can move a lens group in the direction parallel to an optical axis have appeared such as piezoelectric type, linier motor type, and voice coil motor type. Although these technologies are already popular in existing digital cameras, driving mechanism for camera modules in cellular phones needs to be extremely improved because their requirements are totally different from usual digital cameras. Compact image photographing devices, which are installed in mobile apparatuses, should improve portability by reducing their sizes and weights and increase use-time of a battery by reducing power consumption. Weakened suspension (e.g. thickness is 0.02 mm or less) in order to minimize an elastic coefficient for drastic decrease of driving current frequently occurs permanent step-out of a lens group by plastic deformation of the metal suspensions when it comes to getting shocks from accidental drops of a handset. The proposed auto-focusing actuator using conductive polyimide as a flexible diaphragm satisfies these requirements of ultra slim cell phones. This polyimide suspension shows ultimate toughness when it comes to drop-test of cell phones. This actuator also shows high performance quite enough for several mega-pixel camera modules for ultra slim cellular phones; the moving range is up to 0.35 mm, the DC sensitivity is 0.2 mm/140 mA, and the resistance at the terminal is 22 Ohm, whereas the aperture is 6.8 mm, and the overall size is 10 × 10 × 3.95 mm. Most of all, the robustness against drop and shock has been dramatically increased, with no change of reliability under high temperature and high humidity condition, because of the flexibility of the conductive polyimide suspension.