Diaphragm Material Research Articles

A Study on Synthetic Jet Actuator Diaphragm

A synthetic jet actuator (SJA) is one of the most widely used active flow control device which uses a vibrating diaphragm enclosed within a cavity to generate the fluid jet. The effectiveness of the actuator greatly depends upon the design of cavity and orifice and the diaphragm properties. A lot of emphasis is being laid on the cavity and orifice design, but very few literatures can be found dealing with the diaphragm of the SJA. Thus, in this paper a study of the SJA diaphragm actuated by piezoelectric ceramics of different geometries is being presented. Three different diaphragm materials — brass, poly-silicon and aluminum and five different geometries of the piezoelectric actuators — annular disc shaped actuator patch, annular shaped actuator, rectangular shaped actuator patch and circular disc shaped actuator patch and two cantilever arrangements are being considered. A static analysis is carried out and a comparison of the parameters which affect the performance of the SJA is done. Frequency response analysis is also carried out to obtain a better understanding of the diaphragm's structural characteristics. The results thus obtained show that an annular disc piezoelectric patch configuration shows the best behavior as compared to the other actuator configurations and is closely followed by circular disc piezoelectric patch configuration.

Influences of Diaphragm Materials on the Performance of a Microspeaker

ABSTRACTThe purpose of this study was to investigate the influence of a diaphragm material on the performance of a microspeaker. The finite element method was adopted to analyze the mode shapes and the displacement of the diaphragm under a force load. The Rayleigh integral was then calculated to determine the radiated sound pressure and frequency response of a loudspeaker. The location of the voice coil was also investigated. Locating the voice coil at approximately 53% to 76% of coil-radius/diaphragm-radius ratio yielded a favorable mode shape distribution and performance for the loudspeaker. In addition, two loudspeaker designs, Models A and B, were analyzed to determine the effects of the diaphragm material. The numerical results of Models A and B, indicated that the mode shape is a crucial factor when considering the materials used in a loudspeaker diaphragm. The property of a material at the inflection point of a mode shape obviously affects the modal frequency. According to this observation, the most crucial first and second axial symmetric modes in a loudspeaker design can be adjusted and the performance can be improved.

A simply constructed condenser microphone as a teaching aid

To gain a deeper appreciation and a better understanding of the operation of condenser microphones, it is instructive to have a tangible device, which can undergo a fair amount of experimentation. Low cost condenser microphones used in laptops, mobile phones, and other similar devices can be purchased, but not necessarily deconstructed to serve as an effective learning tool. On the other hand, condenser microphones used in recording studios can be taken apart, but can become quite expensive and making any elaborate modifications to the design may prove challenging. As an alternative, we present a functional and cost-effective condenser microphone that can be simply constructed from readily available materials. The device enables students to make changes to the diaphragm material, back plate, electrostatic gap spacing, and the electronic circuit for connection to a lower impedance device. A SPICE model of the condenser microphone is also presented, which was used to guide the design and can provide further insight for the student.

A Simulation Based Geometrical Analysis of MEMS Capacitive Pressure Sensors for High Absolute Pressure Measurement

This paper presents the performance characteristics evaluation of MEMS capacitive pressure sensor. This type of absolute pressure measuring sensor is used for pulse rate measurement. Polysilicon material provides a higher sensitivity when chosen as diaphragm material. Two MEMS capacitive pressure sensors with varying geometries are analyzed in Matlab simulation software. The geometries are very common having parallel plates with spring loaded. In first stage the shape of the parallel plates is circular and in second case of the parallel plate is square. During modeling of these two diffident shaped sensors, the area of parallel plates in both cases is considered as equal. Once the geometries are formed, the electromechanical analyses have been performed. It is observed that these types of pressure sensors can withstand a wide range of absolute pressure from kilo Pascals to several order of mega Pascals. In this work, Matlab environment is employed to model this sensor and accurate model is devised to study its performance. Simulation results are obtained and compared with published work of FEM (Finite Element Method) based Multiphysics simulation platform and full argument is obtained. The proposed model allows handling different parameters affecting the performance of this sensor.

300-POS

Objectives Compared to the diets on which humans evolved, modern diets have increased membrane-stiffening components such as long-chain saturated and trans-fatty acids. Increased vascular stiffness, as measured by pulse wave velocity, is associated with increased incidence and severity of preeclampsia (Hausvater, 2012). As one of the determinants of arterial stiffness, vascular smooth muscle tone is regulated by many factors including endocrine signals as well as nitric oxide, salt, oxidant stress, and mechanical stimulation through cell stretch and calcium signaling. It is generally believed that mechanotransduction in endothelial cell membranes is initiated at the local force-membrane interface by inducing local conformational changes or unfolding of membrane-bound proteins, followed by a cascade of diffusion-based signaling in the cytoplasm (Hoffman, 2011). The objective of this study is to develop a model of how diet-induced endothelial membrane stiffness might impact membrane-based mechanotransduction and cause hypertension. Methods Literature review. Results Because the arterial intima functions as a sensor, blood pressure homeostatic response might be modulated by the flexibility of endothelial membranes. Factors that stiffen cell membranes (such as salt, trans-fatty acids, and sympathetic neurohormones) might restrict protein conformational shift and invoke an inappropriately high contraction response and increased blood pressure. Factors that increase membrane flexibility (such as polyunsaturated fatty acids) might heighten the sensitivity of endothelial membranes to stretch. Similarly to a diaphragm pressure transducer in a barometer, if the diaphragm material is stiff, the signal is attenuated; conversely, a flexible diaphragm makes the instrument more sensitive to pressure. Conclusions Pulse wave velocity might provide a noninvasive method of measuring the success of dietary interventions in reducing endothelial stiffness and risk of preeclampsia. Disclosures N.R. Hart: None.

Fundamental characteristics of a MEMS‐diaphragm actuator using a thermal expansion drive composed of a conductive polymer

Performance of a MEMS actuator using a thermal expansion drive of a conductive polymer (CP) is investigated by applying electricity to it. The actuator consists of a thin polymer diaphragm (5 mm diameter) and a thin CP (ion‐doped polythiophene) layer coated on the diaphragm surface. Polyimide (10 μm thickness) and PET (110 μm thickness) sheets were chosen as the diaphragm materials. The diaphragm is deflected by the thermal expansion of the CP by applying electricity to it. Merits of using the CP instead of metal are realizing flexible actuators and the applicability to a low‐heat‐resistant material diaphragm. The relationship between thickness of the CP layer (10–50 μm thickness) and electrical resistance (30–600 Ω) and the relationship between the input voltage (1–8 V) and the generated diaphragm displacement (several tens of micrometers) were investigated experimentally. These relationships were compared with those in the case of using the thermal expansion of a vapor‐deposited aluminum layer (0.1 μm thickness). The results of the investigation indicate that the diaphragm based on CP can produce the required displacement. In the case the CP‐layer‐based thermal expansion, however, larger input voltage than in the case of the aluminum‐layer‐based thermal expansion is needed to obtain the same displacement amplitudes. Therefore, the main problem concerning use of the CP‐based diaphragm is considered to be enhancing the electrical conductance of the CP layer. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Interference characteristics in a Fabry–Perot cavity with graphene membrane for optical fiber pressure sensors

Due to higher mechanical strength and ultra-thin thickness, graphene is used as a sensitive diaphragm in a Fabry---Perot cavity to improve the sensitivity of pressure sensors. In accordance with the working principle of Fabry---Perot interferometer, a load---deflection mathematical model of fiber-tip pressure sensor with graphene membrane is established based on the large deflection elastic theory of circular membrane. The effects of membrane parameters, including prestressing force and membrane layer number, on deflection mechanical behaviors are studied by using finite element method. Also, the effects of graphene membrane layer and incident light angle on the film reflectivity are obtained according to the refractive index characteristics of the membrane. The simulation results show that an approximate linear relation between loads and deflections exists in the simulated pressure range from 0 to 3.5 kPa, and a theoretical pressure sensitivity of 1,096 nm/kPa for a single-layered graphene membrane can be achieved. To estimate the performance of multi-layered graphene membrane as the diaphragm, an extremely thin 13-layered 125-μm diameter graphene diaphragm is fabricated on the tip of the fiber end, which forms a low finesse Fabry---Perot interferometer. The Fabry---Perot cavity with a length of 40 μm can exhibit a fringe visibility of approximate 0.56 with a measured membrane reflectivity of 1.49 %. The experimental results demonstrate that the use of graphene as diaphragm material would allow highly sensitive and miniature fiber-tip sensors.

A two-step load-deflection procedure applicable to extract the Young's modulus and the residual tensile stress of circularly shaped thin-film diaphragms

We report on a novel two-step load-deflection (LD) formula and technique that enables an accurate extraction of the Young's modulus and the residual tensile stress from LD measurements on circularly shaped thin-film diaphragms. This LD relationship is derived from an adaptation of Timoshenko's plate bending theory, where the in-plane and out-of-plane deflections are approximated by series expansions. Utilizing the minimum total potential energy principle yields an infinite-dimensional system of equations which is solved analytically resulting in a compact closed-form solution. In the appendant measurement procedure, the whole transverse bending characteristic of the diaphragm as a function of the radial coordinate is recorded for different pressure loads and introduced into the novel LD equation in order to determine the elastomechanical parameters of interest. The flexibility of this approach is demonstrated by ascertaining the Young's modulus and the residual tensile stress of two disparate diaphragm materials made of either micromachined silicon or microfiltered buckypapers composed of carbon nanotube compounds.

Invited: A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

Alkaline fuel cells and electrolyzers are attracting increasing interest. This is to a large extent due to the broad selection of catalyst materials not based on resource limited and expensive noble metals. The first fuel cells in practical use were Francis Thomas Bacon’s based on an alkaline electrolyte. The system has been quite successful with good oxygen kinetics, but the electrolyte suffers from carbonization when operated in normal CO2containing air and this has limited the application to space technology and similar niches. The alkaline electrolyzer on the other hand has been the state of art commercial choice for decades and the carbonization problem is absent since oxygen is produced, not consumed. However, the demand for high voltage efficiency has been limited and the alkaline electrolyzer has been optimized in the direction of robustness and long lifetime instead. Today it has become obvious that an energy system based on renewable energy will need conversion of a large amount of electrical energy to fuel for storage and for transport. We believe that from a materials perspective the alkaline electrolyzer has the strongest potential for meeting the manufacturing cost targets given, but voltage efficiency and rate capability must be improved significantly.One important component with room for improvement is the electrolyte which traditionally fills a gap of up to several mm between the electrodes. The resistance can be much reduced if a thin anion conducting membrane or a porous diaphragm is used instead in direct contact with both electrodes (zero gap). In proton exchange membrane (PEM) electrolyzers proton conducting membranes like in PEM fuel cells have been very successful, but for the equivalent anion exchange membranes a similar conductivity has not yet been demonstrated; in contrast it is typically about an order of magnitude lower, which is insufficient [1].The aromatic fluorine free polymer polybenzimidazole (PBI) has been very successful as a high temperature fuel cell membrane when doped with phosphoric acid [2] and it has been shown by Xing and Savadogo [3] that it can also be doped with potassium hydroxide and serve as electrolyte for alkaline fuel cells. See figure 1.In this work the stability of PBI doped with aqueous KOH was studied after storage in 6 M KOH at 85 °C for up to 176 days, i.e. close to half a year [4]. The pristine polymer was supplied by Danish Power Systems ApS and solution cast from DMAc. Three different variants of the PBI were used. 1) The pristine linear PBI, 2) PBI crosslinked by dibromoparaxylene and 3) PBI thermally cured at 350°C.Tensile strength and elastic modulus decreased somewhat during storage, but all membranes remained integral throughout the entire storage period with the exception of the linear untreated sample which disintegrated when handled after the full 176 days. A gradual weight loss was seen for all membranes but the effect was much reduced for the crosslinked and the cured pieces. The thermally cured membrane lost less that 10 mass %. Viscosity measurement on the linear PBI (the only one soluble) showed a decreasing molecular weight over time of storage. The materials were also examined by IR, NMR and TGA.Finally, electrolysis tests were made including comparison with a commercial diaphragm material (Zirfon). The conductivity of the alkali doped PBI samples was around 0.05 S cm-2 at 85°C, while that of Zirfon was ca. 0.2 S cm-2, but since Zirfon is much thicker to ensure a low bubble point pressure the practical area specific resistances were more or less equal and the cells showed very similar polarization characteristics.[1] G. Merle, M. Wessling and K. Nijmeijer. J. Membrane Sci. 377 (2011) 1– 35[2] Q. F. Li, J. O. Jensen, R. F. Savinell and N. J. Bjerrum. Prog. Polym. Sci. 34(2009) 449[3] B. Xing, O. Savadogo, Electrochemistry Communications 2(2000) 697-702[4] D. Aili, M. K. Hansen, R.F. Renzaho, Q. F. Li, E. Christensen, J. O. Jensen and N. J..Bjerrum. J. Membrane Sci. 447 (2013) 424–432

Enhanced sensitivity with extended linearity in MEMS piezoresistive pressure sensor

Focused research efforts on enhancing the sensitivity of piezoresistive MEMS pressure sensors have been made in the past. Most of these techniques applied to enhance sensitivity have depended on manipulating the geometries of the diaphragm, selection of the diaphragm material and improving the piezoresistive properties. Piezoresistors change their resistance linearly proportional to the bending stresses induced in the diaphragm on application of the pressure. Therefore the successful design of a high sensitivity piezoresistive pressure sensor totally depends on the efficiency with which the induced stresses are harvested in the transduction process. Introduced is an innovative way to harvest the maximum stresses. The dual Wheatstone bridge implemented with eight piezoresistors effectively converts the XX and YY plane stresses into electrical voltage to double the sensitivity. The simulation experiment results show that the sensitivity of the 91.72 µV/V/kPa with ensured linearity over 0–14 kPa using a 5 µm-thick diaphragm with a single bridge can now be achieved by employing a 7 µm-thick diaphragm with double Wheatstone bridges but with excellent linearity extended over 0–54 kPa. Almost the same trend is seen between the 3 and the 5 µm-thick diaphragms. Thus, this technique paves the way for achieving large voltage sensitivity bundled with a high level of linearity over a wide pressure range by using thick diaphragms.

Development and Characterization of Porous Silicon Nitride Tubes

As the porous aluminous porcelain diaphragm tubes in the electrolytic cells, employed in the aqueous reprocessing of spent nuclear fuels, undergo leaching in concentrated nitric acid, corrosion resistant 600 mm long silicon nitride tubes were developed indigenously by reaction bonding of pre-formed silicon green tubes in nitrogen atmosphere. The process parameters for the fabrication were optimized to produce tubes with density, porosity and liquid permeability in the range 2.2-2.5 kg.dm–3, 20-25% and 10–5-10–6 cm.s–1 respectively. The performance of the fabricated tubes was evaluated by using them as the diaphragm tubes in the electrolytic destruction of 4 M nitric acid and the efficiency of the process was compared with that for a cell in which a commercially available silicon nitride tube was used as the diaphragm material. Though performance of both the tubes was comparable, the resistance offered by the indigenous tube to the flow of current through it was much lower than that of the other tube.

Study on the Performance of Woven Basalt Filament Diaphragm Fabric

The tensile properties of basalt filament were measured and compared with these of E-glass fiber. The plain basalt filament fabric (PBFF), twill basalt filament fabric (TBFF) and plain glass filament fabric (PGFF) that woven by the CSW-03 loom under the same fabric density were used to make diaphragm preforms. Thermoplastic acrylic resin was chosen to coat on the diaphragm preforms using Werner Mathis AG LTF97885 coating machine when the coating thickness is 0.1mm, curing time is 30min. Tensile test was carried out on the diaphragm performs and coating diaphragm by 3380Instron advanced testing machine. Effect of curing temperature (<200°C) on tensile properties of diaphragm materials was investigated. The coating PBFF and the coating TBFF were compared to analysis the effect of organization structures on the elastic modulus. The results indicated that the best elastic modulus of diaphragm materials was achieved when the curing temperature was 120°C. PBFF is more suitable for diaphragm materials than PGFF and TBFF. The proposed curing temperature for making diaphragm with different elastic modulus ranges from 100°C to 140°C.

Design characterization and testing of a custom air horn

Construction and testing of an air horn can provide educational insight into how certain design decisions can influence resulting acoustic properties. Using readily available materials such as pvc pipe and tin sheeting, one can construct an air horn capable of producing sound waves in the 100+ decibel range and frequencies between 150 and 400 Hz. Upon completion of a prototype, many experimental opportunities are available. The degradation of sound intensity over a distance can be tested by use of a sound level meter. Due to the unidirectional behavior of the sound waves from the horn, samples from different distances and angles from the source can provide more understanding of how sound propagates as a wave in an open environment, as opposed to it being a simple directional wave. Upon completion of the testing, changes to the initial construction design can be implemented to investigate the relationship between the new model’s performance and the prototype’s. The air horn provides many opportunities for experimentation and testing. For example, frequencies and sound intensity can be altered by making design adjustments such as: diaphragm size, diaphragm material, housing material, bell size, nozzle length, etc. With a better understanding of the inner workings of these sound sources, one could use this design as a blueprint to expand the concept to either much larger or much lower frequency ranges which have applications in many different fields of study.

A Flow Measurement Technique Using a Noncontact Capacitance-Type Orifice Transducer for a Conducting Liquid

The ordinary orifice transducer widely used in process industries for flow rate measurement produces a differential pressure which is generally measured by a DP cell and thus may suffer from various problems like leakage of process fluid, corrosion of diaphragm materials, etc. In this paper, the design of a noncontact capacitance-type orifice transducer for the measurement of flow rate of a conducting liquid through a pipeline has been described. In the proposed transducer, the use of a diaphragm-type DP cell is not needed, and thus, the problems associated with DP cell are avoided. The theoretical analysis of the flow transducer is presented in this paper. The performance of the flow transducer along with that of the signal conditioner for flow of tap water through a pipeline has been tested experimentally. The experimental results are presented in this paper. A good linearity and repeatability of the sensor capacitance, transducer output, and signal conditioner output with flow rate have been observed.

High-sensitivity fiber-tip pressure sensor with graphene diaphragm

A miniature fiber-tip pressure sensor was built by using an extremely thin graphene film as the diaphragm. The graphene also acts as a light reflector, which, in conjunction with the reflection at the fiber end-air interface, forms a low finesse Fabry-Perot interferometer. The graphene based sensor demonstrated pressure sensitivity over 39.4 nm/kPa with a diaphragm diameter of 25 μm. The use of graphene as diaphragm material would allow highly sensitive and compact fiber-tip sensors.

Microfabrication of magnetically actuated PDMS–Iron composite membranes

We report a new approach to fabricate suspended composite membranes consisting of carbon-coated iron nanopowder uniformly dispersed in a polydimethylsiloxane matrix. The approach is based on the use of selectively photopolymerized thick SU-8 layer wherein the unexposed to ultraviolet light area represents the sacrificial layer. Circular composite membranes of different sizes are designed, fabricated, and characterized. The membranes' deflections upon the application of an external magnetic field, measured by optical microscopy, show a quadratic dependence on the diameter, in agreement with the theory. Tensile tests proved that the fillers do not affect the elastic properties of the matrix, since the Young's modulus of the composite material is similar with the one of the pure polymer. The versatile approach presented in this work allows to easily and rapidly fabricate suspended composite membranes that provide diaphragm materials with excellent performances, which can find broad applicability in microfluidic applications (valves, micro-pumps) and in MEMS technology (tactile displays, mobile devices).

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.

METHOD AND APPARATUS FOR CONTROLLING MATERIAL VIBRATION MODES IN POLYMER AND PAPER HIGH PERFORMANCE SPEAKER DIAPHRAGMS

A method for reducing the radiation amplitude of material vibration modes (division vibrations) from a loudspeaker transducer diaphragm mechanically vibrated for the purpose of transforming an electrical signal into an acoustic signal. The diaphragm material may consist of formed paper or plastic sheet materials or molded paper pulp. The amplitude reduction of material vibration modes and pressure waves within the diaphragm material is accomplished by impressing small, shaped structures within the diaphragm material at critical locations determined by measurement with laser vibration analysis or position sensitive transient analysis of a loudspeaker transducer. The method is applied to the diaphragm material after it has been formed into the shape of a loudspeaker transducer diaphragm, either before or after the diaphragm has been assembled into a loudspeaker transducer.

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.

Combinatorial Search for Ni–Nb–Ti Thin Film Amorphous Alloys with High Corrosion Resistances

In this paper, we present a combinatorial search for novel Ni–Nb–Ti thin film amorphous alloys suitable for use in diaphragm-type microelectromechanical systems (MEMS) vacuum sensors. The corrosion resistances to ClF3 gas and heat resistances of the thin films were evaluated by a combinatorial method that enables efficient searching for candidate materials. The combinatorial evaluation revealed that Ni56Nb33Ti11 and Ni49Nb35Ti16 thin film amorphous alloys exhibit a high heat resistance and a high corrosion resistance to ClF3 gas. Moreover, both samples exhibited high fracture stresses of over 1.0 GPa. Both samples were assessed to be suitable diaphragm materials for diaphragm-type MEMS vacuum sensors. We also fabricated and evaluated a simple diaphragm-type MEMS vacuum sensor using a Ni49Nb35Ti16 thin film amorphous alloy; the results confirmed the suitability of this amorphous alloy as a diaphragm material.