Use Of Pressure Sensors Research Articles

Collateral circulation alters downstream hemodynamic stress caused by intracranial atherosclerotic stenosis

Objectives: Fractional flow reserve (FFR) accurately predicts the degree of stenosis and is now widely used to identify clinically significant severe coronary artery lesions. In the current study, we utilized a similar indicator, fractional flow (FF), to determine the hemodynamic impact of symptomatic intracranial atherosclerotic stenosis (ICAS) and to assess the correlation of FF with the severity of stenosis and collateral circulation.Methods: Patients with symptomatic ICAS (70–99% stenosis) confirmed on digital subtraction angiography (DSA) were consecutively recruited. FF was obtained during DSA examination with the use of pressure sensors and was measured as a ratio, comparing measurements distal to an ICAS lesion (Pd) and within the aorta (Pa). The degree of leptomeningeal collateralization was graded from zero (absent) to four (complete compensatory). The correlation between FF, anatomical stenosis, and collateral status was then analyzed.Results: Twenty-five patients with a mean age of 55.6 years were analyzed. The median percentage of stenosis and median FF were 82.3 and 0.68%, respectively. Eleven patients were found to have poor collateralization (grade 0-2), and fourteen patients were identified with good collateral circulation (grade 3-4). Overall, the hemodynamic impact of an atherosclerotic lesions worsened (decreased FF) as the percentage of stenosis increased, although this did not reach statistical significance (r = −0.398, p = 0.06). However, the status of collateralization significantly altered this correlation, worsening the hemodynamic impact in patients with poor collateral circulation (r = −0.677, p = 0.032). There was no difference in patients with good collateral circulation (r = −0.279, p = 0.356).Conclusion: An anatomically severe (70–99%) symptomatic ICAS lesion may generate significant hemodynamic stress downstream as assessed by the indicator FF, particularly in patients with poor collateral circulation. Further, good collateralization may mitigate this hemodynamic impact, partially explaining the protective effect of collateral circulation against recurrent stroke in such patients.

Microprocessor system for collection meteoparameters based on Arduino platforms

The research the possibility of creating a compact universal module for collecting, processing and transmission of meteorological parameters of the atmosphere based on modern microprocessor systems and a set of corresponding sensors. Created model of a portable weather station conducted experimental research systems measure the speed and direction of air flow. It is shown, that the use of pressure sensors in the scheme of differential pressure gauge and a system of rotation allows for measuring the speed and direction of air flow in practical meteosystems.In future it is planned search for the optimal design of the tubes in the scheme of differential manometradlya specific pressure sensors. This will improve the sensitivity and enhance the ability of the practical use of such devices.

Low-power operation of a barometric pressure sensor for use in an automatic fall detector.

The use of a barometric pressure sensor in a wearable fall detector has been shown to improve the detection accuracy by determining the altitude change associated with the fall event. However, the barometer is a high-power-consuming sensor. This paper proposes a fall detection approach using a hermetically sealed and waterproof enclosure incorporating a small window covered by a semi-permeable membrane (SPM) to delay the equilibrium of internal and external pressures. This feature can be utilized to limit the time the barometer is powered but still capturing critical pressure information to discriminate fall and non-fall events. The proposed fall detection system is evaluated with an existing data set of simulated fall and activities of daily living in which the barometric pressure data are delayed using a mathematical model of the enclosure and SPM assembly. Also, a benchtop test is performed to estimate the power and battery life. The proposed fall detection system achieves 94.0% sensitivity and 90.0% specificity with an estimated battery life of 995.7 days.

Highly sensitive, wearable and wireless pressure sensor using free-standing ZnO nanoneedle/PVDF hybrid thin film for heart rate monitoring

Highly sensitive, wearable and wireless pressure sensor was successfully fabricated based on the zinc oxide (ZnO) nanoneedle/poly(vinylidene difluoride) (PVDF) hybrid film. The nanoneedle structure of ZnO with large aspect ratio and hexagonal vertical grown pyramid form could lower the elastic modulus of the hybrid film compared to the ZnO nanorod. Due to its high permittivity, low polarization response time and outstanding durability, the hybrid film can be applied for a real-time pressure sensor to monitor the heart rate. Notably, the lowest detectable pressure of the hybrid film was as small as 4Pa. Furthermore, the reduced graphene oxide (rGO) electrode-based Bluetooth antenna attained high peak gain (2.70dBi) and radiation efficiency (78.38%), which was applicable to be used as an omnidirectional antenna to transmit wireless signal to the smart phone. Interestingly, the received wireless heart beat signal within a distance of 8m was more sensitively measured on the radial artery than carotid artery without distortion and time delay, and it had a similar oscillation in comparison with the wire pressure sensor. This approach offers a valuable and promising tool for producing the commercial and continuous wireless pressure sensor for use in routine biomedical research and critical healthcare.

PD6-05 EVALUATING AN IMPLANTABLE WIRELESS PRESSURE SENSOR FOR USE IN THE URINARY TRACT

You have accessJournal of UrologyTechnology & Instruments: Surgical Education & Skills Assessment I1 Apr 2014PD6-05 EVALUATING AN IMPLANTABLE WIRELESS PRESSURE SENSOR FOR USE IN THE URINARY TRACT Brian Le, Alberto Colombo, Harry Rowland, and Kevin McVary Brian LeBrian Le More articles by this author , Alberto ColomboAlberto Colombo More articles by this author , Harry RowlandHarry Rowland More articles by this author , and Kevin McVaryKevin McVary More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.513AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Pressure information is an essential component of urodynamics and the evaluation for obstructive uropathy. Current methods of obtaining pressure information require a direct wired connection, which causes discomfort and limits repeated measurements and widespread use. Here we evaluate a novel wireless induction technology that would allow wireless measurements to be taken through tissues using a self-contained microcircuit with an external reader. METHODS We conducted in vitro and animal experiments to evaluate the signal strength, accuracy and feasibility of a wireless pressure sensing system in the GU tract. Prior to implantation, bench tests were carried out to evaluate the sensors’ pressure reading accuracy at a range of different pressures and distances. In animal trials, rats were anesthetized and a cystotomy was made to insert a self-contained Induction-Capacitance (LC) circuit into the bladder and then sutured closed. A calibrated catheter with a pressure gauge was inserted into the bladder via the urethra. The bladder was cycled from empty to capacity several times while readings were obtained. All experiments were approved by the Institution’s Animal Safety Board. RESULTS Bench tests on wireless sensors showed accuracy within +/- 1.5 mmHg up to 9 cm distance in the urinary tract pressure range of 0 to 50 mm Hg. When the sensor was inserted in the bladder of rats, the sensors responded to an artificial increase in bladder pressure with the emission of a proportionally decreasing resonant frequency signals (figure 1). As expected a declining resonant frequency is recorded with increasing pressure. A linear regression could be detected with r=-0.75. CONCLUSIONS Wireless sensors can be effectively used in the urinary system and can provide a robust signal through tissues and in a high salt environment in a predictable fashion. We expect that the concordance with wired readings will greatly increase with the next generation of wireless sensors with ceramic encapsulation that will prevent frequency drifting and thus more accuracy. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e131-e132 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Brian Le More articles by this author Alberto Colombo More articles by this author Harry Rowland More articles by this author Kevin McVary More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Sensor Placement and Leakage Localization Considering Demand Uncertainties

Detecting and locating leaks in water distribution systems is of great interest. For the localization of leaks we make use of pressure sensors alongside a calibrated hydraulic EPANET model of the investigated system. Leakage localization is solved with a Differential Evolution algorithm. For sensor placement we use a non-binarized leak sensitivity matrix with a projection-based leak isolation approach. Additionally, the effect of uncertain hydraulic model parameters on the measurement quantities is investigated by Monte Carlo simulations and was incorporated in the sensor placement algorithm. Uncertainty analysis, sensor placement and leakage location was tested on two hydraulic systems.

Design and Analysis of a Non-Vision-Based System for Detecting Unstable Gait

An unstable gait provides early warning of more serious conditions. In this study, we propose the use of pressure sensors embedded into a shoe pad along with a 3D accelerometer fastened to the knee. We have implemented a portable gait-measuring device integrated with a ZigBee wireless sensor network. Moreover, the step length, step speed, and step distance are easily calculated in the user interface. These data can then be used to distinguish the seven decision points of a complete gait cycle. Analysis of the gait cycle is done using fuzzy logic. The detected gait phases can be compared with standard gait parameters from the literature. Thus, the analyzed gait parameters can provide early detection of the emergence of an unstable gait. Finally, because our system measures knee flexion angle, it can detect the swing phase of the gait cycle.

A Wet/Wet Differential Pressure Sensor for Measuring Vertical Hydraulic Gradient

Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct measurements of the head difference with a manometer. Making separate head measurements allows for the use of electronic pressure sensors, providing large datasets that are particularly useful when the vertical hydraulic gradient fluctuates over time. On the other hand, using a manometer-based method provides an easier and more rapid measurement with a simpler computation to calculate the vertical hydraulic gradient. In this study, we evaluated a wet/wet differential pressure sensor for use in measuring vertical hydraulic gradient. This approach combines the advantage of high-temporal frequency measurements obtained with instrumented piezometers with the simplicity and reduced potential for human-induced error obtained with a manometer board method. Our results showed that the wet/wet differential pressure sensor provided results comparable to more traditional methods, making it an acceptable method for future use.

Joined-Wing Wind-Tunnel Test for Longitudinal Control via Aftwing Twist

Wind-tunnel tests were conducted to assess the use of aftwing twist for longitudinal control in a joined-wing aircraft. Forces and moments required for pitch control were measured experimentally, along with limited chordwise pressure measurements. Comparisons of aerodynamic panel model predictions with experimental data were used to calculate camber and center-of-pressure corrections. The lift-curve slope measured at four flow speeds compared favorably to linear predictions over the range of 20° angles of attack. The pitching moment coefficient was linear at the three lower flow speeds for untwisted and twist-down aft wings over a narrower range of about 10° angles of attack. The pressure exhibited shifts in the chordwise distribution at angles of attack coinciding with the change in the moment curve slope. The large spread in the twist-up aftwing configuration drag and pitching-moment coefficients indicated flow separation on the aft wing, even at small angles of attack, deterring the twist effectiveness. Independent forward and aftwing measurements and more extensive use of pressure sensors are recommended in future experiments to confirm the apparent separation and interference effects that must be avoided if aftwing twist is to be used for pitch control on a joined wing.

VENOUS NEEDLE DISLODGEMENT: THE PITFALLS OF VENOUS PRESSURE MEASUREMENT AND POSSIBLE ALTERNATIVES, A REVIEW

The historical development of the use of pressure sensors as protective system against blood loss to the environment is reviewed. In spite of early warnings about the deficiency of such sensors, the venous pressure sensor is still formally accepted as protective system against blood loss to the environment in case of leaks or needle dislodgement. The early warnings were corroborated by publications and accident reports. Several alternative methods have been developed or described in the literature recently. These methods are critically reviewed. The conclusion is that external monitors are currently the only available alternatives, although long-time clinical experience is missing. Methods employing sensors integrated into dialysis machines have been described but it is unlikely that any of these methods will become available in the immediate future.

Distribution theory approach to implementing directional acoustic sensors

The objective of directional acoustic sensors is to provide high directivity while occupying a small amount of space. An idealized point sensor achieves this objective from a knowledge of the spatial partial derivatives of acoustic pressure at a point in space. Direct measurement of these derivatives is difficult in practice. Consequently, it is expedient to come up with indirect methods. The use of pressure sensors to construct finite-difference approximations is an example of such a method. This paper utilizes the theory of distributions to derive another indirect method for estimating the various spatial partial derivatives of the pressure. This alternate method is then used to construct a multichannel filter which processes the acoustic pressure by mean of three-dimensional integral transforms throughout a 6epsilon-length cube centered at the origin. The output of the multichannel filter is a spatially and temporally filtered version of the pressure at the origin. The temporal filter is a lowpass Gaussian filter whose bandwidth is inversely proportional to epsilon. Finally, the lattice method for numerical multiple integration is utilized to develop a discrete-spatial version of the multichannel filter.

A Wet/Wet Differential Pressure Sensor for Measuring Vertical Hydraulic Gradient

Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct measurements of the head difference with a manometer. Making separate head measurements allows for the use of electronic pressure sensors, providing large datasets that are particularly useful when the vertical hydraulic gradient fluctuates over time. On the other hand, using a manometer-based method provides an easier and more rapid measurement with a simpler computation to calculate the vertical hydraulic gradient. In this study, we evaluated a wet/wet differential pressure sensor for use in measuring vertical hydraulic gradient. This approach combines the advantage of high-temporal frequency measurements obtained with instrumented piezometers with the simplicity and reduced potential for human-induced error obtained with a manometer board method. Our results showed that the wet/wet differential pressure sensor provided results comparable to more traditional methods, making it an acceptable method for future use.

Relationships among Throat Sensation, Beer Flavor, and Swallowing Motion While Drinking Beer

The sensation in the throat while drinking is an important beer quality. To evaluate this feeling, we developed a noninvasive biometric system for measurement of the swallowing motion while drinking. The system measures movement of the Adam's apple, provides an electromyogram (EMG) of the throat musculature, and records swallowing sounds through the simultaneous use of pressure sensors, EMG electrodes, and microphones, all mounted on the throat surface. The period of larynx heave, throat muscle activity, and intervals of swallowing sound were used as analytical parameters. Eight beer samples with different throat sensation features, confirmed by sensory evaluation, were investigated. The subjects swallowed beer successively for 15 sec to measure throat movement while drinking a glass of beer. Adam's apple movement time and muscle activity were negatively correlated with the sensory evaluation. The results indicated that a beer with a light-finish sensation had short laryngeal movement time and low muscle activity. Total nitrogen and bitterness units were correlated with laryngeal movement time and muscle activity and were negatively correlated with light-finish sensation. It is expected that this system could characterize the difference in swallowing motion while drinking beer and the sensation in the throat. We also expect to be able to apply this biometric system to product development and marketing in the future.

Composite Si/PS membrane pressure sensors with micro and macro-porous silicon

Porous Silicon (PS) is a versatile material with many unique features making it viable in the field of Microelectromechanical Systems (MEMS). In this paper, we discuss the optimization of formation parameters of micro and macro PS with different porosity and thickness for use in pressure sensors. The optimized material is used in the fabrication of composite Si/PS membranes in piezo-resistive pressure sensors and tested. Pressure sensors with composite membranes have higher sensitivity than those with single crystalline silicon membrane with the sensitivity increasing as the porosity increases. For the same porosity and thickness of the PS layer, Si/micro PS membranes exhibit higher sensitivity than Si/macro PS ones. The offset voltage in these sensors is found to be high and can be due to the stress induced in the membrane during PS formation. Offset voltage and stress values are found to be higher in composite membranes with micro PS as compared to macro PS.

A new methodology for investigating airbag-induced skin abrasions

Although airbags have been shown to reduce the incidence of life-threatening injuries, they have increased the risk of minor injuries such as those to the skin. Based on the distribution of injuries that can be directly attributed to the airbag itself, it is believed that shear loading exists as a mechanism for these skin injuries. The purpose of this study was to develop a new methodology designed to assess the injury potential from different types of airbag with respect to shear loading. This new methodology utilized a high-speed impactor to accelerate the airbag fabric past a sample of skin. Contact normal forces were monitored by the use of pressure sensors, and fabric velocity was determined from a high-speed video. The abraded skin samples were analysed using light microscopic analysis and ultraviolet light source photography. A new abrasion rating method was developed called the total abrasion score, which allows for quantifiable differentiation between the abrasions caused by different airbag fabric and seam types.

高温動作用ダイヤフラム一体型圧力センサの開発

A pressure sensor for use in a high temperature atmosphere (150˜250°C) has been developed. The pressure sensor consists of Cr-O thin film strain gauges, electrode films and an oxidation resistance film, which are all sputter deposited on a metal diaphragm covered with an SiO2 insulator. For the pressure measurement, a photolithographically patterned Wheatstone bridge circuit of the Cr-O thin film strain gauges was used. The output voltages showed good linearity with pressure and little hysteresis even at a temperature of 250°C. In order to prevent oxidation of the strain gauges at high temperatures, some sputtered oxidation resistance films were examined. It was shown that non-oxide films such as AlN and Si3N4 films have good characteristics to prevent oxidation of the strain gauges.

A flexible encapsulated MEMS pressure sensor system for biomechanical applications

The use of pressure sensors made of conductive polymers is common in biomechanical applications. Unfortunately, hysteresis, nonlinearity, non-repeatability and creep have a significant effect on the pressure readings when such conductive polymers are used. The objective of this paper is to explore the potential of a new flexible encapsulated micro electromechanical system (MEMS) pressure sensor system as an alternative for human interface pressure measurement. A prototype has been designed, fabricated, and characterized. Testing has shown that the proposed packaging approach shows very little degradation in the performance characteristics of the original MEMS pressure sensor. The much-needed characteristics of repeatability, linearity, low hysteresis, temperature independency are preserved. Thus the flexible encapsulated MEMS pressure sensor system is very promising and shows superiority over the commercially available conductive polymer film sensors for pressure measurement in biomechanical applications.

A laser plantar pressure sensor for the diabetic foot

This paper describes the design and development of a high-resolution pressure sensor for use in the field of foot pressure measurement. The device uses an interferometry technique that involves the use of a laser light directed onto a pressure sensitive plate. The pressure plate compresses when a load is applied, and it is this compression which is measured by the interferometry technique. The interference pattern (interferogram) produced represents the pressure distribution across the plate. The interferogram is inputted into the computer using a high pixel CCD camera and video capture card. A fringe analysis program then converts the interferogram into a three-dimensional image of the pressure distribution. A prototype system is described and the initial results show that the system can produce a high resolution image with dynamic capabilities.

Polyvinylidene fluoride film sensors for measurement of unsteady pressures on aerodynamic surfaces

The design and calibration of a unique thin unsteady pressure sensor for use on small-scale marine propellers is presented. The Polyvinylidene Fluoride film-based sensor incorporates a miniature interface circuit suitable for use where space is a premium. Sensitivity of the sensor is comparable to high-quality microphones. Calibration is performed using an acoustic source and an industry-standard microphone. Evaluation of the sensor’s performance is presented for white noise unsteady pressure input. Results show excellent agreement between sensor-measured pressures and standard microphone-measured pressures.

Double SOI Structures and Device Applications with Heteroepitaxial Al2O3 and Si

Growth and properties of a double SOI (Si-on-insulator) structure, which consists of epitaxial Al2O3 as an insulator layer and epitaxial Si layers, are discussed. LP-CVD (low-pressure chemical vapor deposition) for γ- Al2 O3(100) growth on Si(100) substrates was combined with Si CVD through a sample exchanging chamber with reflection high-energy electron diffraction (RHEED) and quadrupole mass spectrometer (QMS) to grow successively and analyzed without exposure to air. These epitaxial multilayers were characterized by RHEED, Auger electron spectroscopy (AES), cross-sectional transmissin electron microscopy (TEM) and etching method. Metal-oxide-semiconductor (MOS) field effect transistor (FET) mobility was also studied on each Si layer. Both Si layers showed similar defect density and mobility. This double SOI structure was applied to fabrication of a pressure sensor for use at elevated temperatures up to 300° C.