Reliability Of Pressure Measurements Research Articles

From wires to waves, a novel sensor system for in vivo pressure monitoring.

Pressure monitoring in various organs of the body is essential for appropriate diagnostic and therapeutic purposes. In almost all situations, monitoring is performed in a hospital setting. Technological advances not only promise to improve clinical pressure monitoring systems, but also engage toward the development of fully implantable systems in ambulatory patients. Such systems would not only provide longitudinal time monitoring to healthcare personnel, but also to the patient who could adjust their way-of-life in response to the measurements. In the past years, we have developed a new type of piezoresistive pressure sensor system. Different bench tests have demonstrated that it delivers precise and reliable pressure measurements in real-time. The potential of this system was confirmed by a continuous recording in a patient that lasted for almost a day. In the present study, we further characterized the functionality of this sensor system by conducting in vivo implantation experiments in nine female farm pigs. To get a step closer to a fully implantable system, we also adapted two different wireless communication solutions to the sensor system. The communication protocols are based on MICS (Medical Implant Communication System) and BLE (Bluetooth Low Energy) communication. As a proof-of-concept, implantation experiments in nine female pigs demonstrated the functionality of both systems, with a notable technical superiority of the BLE.

A highly sensitive diaphragm pressure sensor based on fiber Bragg grating with multiprobe configuration

The demand for accurate low-pressure sensing has become indispensable across diverse industries and research domains, where meticulous pressure monitoring holds paramount significance. This research work presents the development of a multiprobe extrinsically sensitive low pressure fiber Bragg grating (FBG) sensor. Three distinct diaphragm-based FBG sensing probes, equipped with silicone diaphragms of 0.5 mm, 1 mm, and 2 mm thickness, are developed within a unified assembly. This design offers the flexibility to select a probe based on the pressure magnitude and desired sensitivity and resolution. The displacement of diaphragm centers within the probes, caused by pressure variations in gas pipe channels, is actuated through an FBG-cantilever system. The sensor exhibits a dynamic range spanning 0 to 10 psi, featuring a peak sensitivity of 1.635 nm/psi. With a negligible hysteresis of 0.2 % observed in a complete operational cycle, the sensor demonstrates consistent stability across various constant pressure conditions, characterized by an average transient of <1 %. Furthermore, cyclic testing reveals an average deviation of 1.58 % in sensor response. This innovative sensor offers promising avenues for industrial applications and research and development endeavors that necessitate precise and reliable pressure measurements in the low pressure domains.

Efficiency and Impact of Hypnoanalgesia for Cardiac Catheterisation in Paediatric Population.

In a prospective study, patients aged <16 years who underwent CC under hypnoanalgesia from January to December 2021 were included. Pain and anxiety were assessed using the analgesia nociception index (ANI) and the visual analogue scale (VAS). Sixteen patients were included; the mean age was 10.5 years, and the mean weight was 37 kg. Catheterisations were interventional in 10 patients (62.5%). Hypnoanalgesia indications were general anaesthesia (GA) contraindication in four patients (25.0%), the need for accurate pressure measurements in three patients (18.7%), and interventionist/patient preferences in nine (56.3%). CC was accomplished in 15 patients (93.7%), even in complicated cases. In one case, pulmonary artery pressures were normalised compared to previous catheterisation under local anaesthesia alone. The VAS score was under 5/10 for all patients. The ANI remained above 50 (no painful zone) for all but one patient. There was no significant decrease in the ANI during the intervention compared to the baseline (p = 0.62). No complications were reported. Paediatric CC is feasible and safe under hypnoanalgesia, even in complicated cases. Hypnoanalgesia was efficient in managing pain and stress, and it ensures more reliable pressure measurements.

Clinical hypnosis associated with local anesthesia for cardiac catheterization in pediatric population

Hypnosis is a promising non-pharmacological adjunct treatment for improving pain and interventional anxiety management in pediatric interventions. Its efficiency and impacts in pediatric cardiac catheterization (CC) are unknown. Evaluate hypnosis efficiency and impacts in pediatric cardiac catheterization. This a prospective monocentric study, all patients aged < 16 years who had CC under hypnosis with local anesthesia from January to December 2021 were included. Pain and anxiety were evaluated by the ANI (Analgesia Nociception Index) measured during the intervention, and the Visual Analogue Scale (VAS) assessed by the patients after the intervention. Sixteen patients were included, mean age was 10.5 years |range 4–16 years], mean weight was 37 kg [range 15–69 kg]. Catheterizations were interventional in 10 patients (62.5%) and for diagnostic purposes in 6 patients (37.5%). Hypnosis indications were general anesthesia (GA) contraindication in 4 patients (25.0%), the need of accurate pressures measurements without GA interference in 3 patients (18.7%) and interventions/patients preferences in 9 patients (56.3%). In one patient of 4 years old, the hypnotic status was not achieved and the procedure was aborted before the installation. CC was accomplished successfully in 15 patients (93.7%) even in complicated cases; large atrial septal defect (ASD) closed with 39 mm Occlutech device in 16 years old patient, and a large ASD 26 mm/m2 closed by 18 mm Amplazer device in 7 years old patient. Mean procedures and fluoroscopy times were 67.5 and 5.3 min, respectively. In one case, pulmonary artery pressures were normalized comparing to previous catheterization under local anesthesia alone leading to the cancellation of cardiac surgery on mitral stenosis. No additional medication was necessary in all patients. VAS score was under 5/10 in all patients. The ANI remained above 50 (non-painful zone) in all but one patient. There is no significative decrease of the ANI during the intervention comparing to the baseline (P = 0.62). One patient with language difficulties had short and transient decrease of the ANI (49) during one minute after the puncture (Table 1). Pediatric CC are feasible under hypnosis even in complicated cases. Hypnosis was efficient to manage pain and stress in all cases. It ensures more reliable pressure measurements.

Clinical Assessment of Customized 3D-Printed Wrist Orthoses

Plaster casting has been effective in fracture rehabilitation due to its immobility capability. Thermoplastic casting gains some efficiency and convenience from clinical processing but fitting and immobility are two major tradeoffs. Three-dimensional (3D)-printed braces have demonstrated improvements in innovation, customization, and appearance, but one may question their effectiveness in rehabilitation. Via a science-based data-centric approach, we evaluated the feasibility of customizing 3D-printed braces for wrist fractures after surgery. First, we established a framework for determining a proper timeframe for reliable pressure measurement for plaster casts, devised a method to evaluate the immobilization capability of the plaster casts and customized braces, and assessed changes in immobilization capability due to the clearance adjustment of customized braces. Second, we compared the customized wrist braces and plaster casts in immobilization capability and functional effectiveness in clinical trials. Thirty-three patients were recruited (9, control; 24, experimental). Both the Disability of Arm, Shoulder, and Head, and the Manual Ability Measure surveys showed significant differences between the control and experimental groups after brace wearing time frames of 2, 4, 8, and 12 weeks, and 6 and 12 months. We found that customized braces can match plaster casts in immobilization ability and can promote effective functional recovery.

Effect of the magnetic field on the operation of ionisation gauges

Hot cathode ionisation gauges are the only reliable pressure measurement devices suitable for both high and ultra-high vacuum measurement. These devices are characterized by low accuracy that is hardly better than 20%. The sources of loss of accuracy are documented in the literature although their quantification and details are not fully understood. In the present work, simulations of Bayard-Alpert and extractor gauges were performed under the influence of uniform magnetic fields up to 30 Gs. Results are in qualitative agreement with measurements taken previously with the Bayard-Alpert gauge. Both gauges are sensitive to low intensity magnetic fields which may be present in vacuum chambers. However, the extractor gauge proved to be more stable in the presence of a magnetic field due to its ring-shaped cathode.

Experimental Study on Measurement of Interfacial Pressure in Granular Materials

Abstract The properties of storage system structures were largely determined by the particle size and compressive modulus of the granular material inside, which is an important issue for silo structure design. The large compressibility and complex contact relationship of granular materials in the cell are needed for the reliable pressure measurement. A set of testing system and experiment method were designed to reveal the size effect of earth pressure cells in the loading and unloading process of granular materials. Different compressive moduli were adopted for the selection of the appropriate granular particle size. Four types of granular materials including fine sand, coarse sand, rapeseed, and wheat were used as raw materials. Three types of earth pressure cells were used in this study with different sizes, and a series of loading and unloading tests were conducted with liquid. The interaction between the cell and granular material and its main factors were discussed. The results show that the pressure exhibits a linear relationship with the strain in the loading and unloading process in liquid surroundings. Owing to the interaction between the cell and granular materials, the pressure increased linearly with the strain in the loading process as well as a nonlinear relationship were exhibited in the unloading process. In the unloading process, an exponential model was proposed to simulate the pressure and strain based on the significant hysteresis phenomenon observed during unloading process. The hysteresis ratio (R) index was adopted to evaluate the hysteresis. It was found that the material type of surroundings and particle size were believed to be the two major factors affecting the R value. To improve the accuracy of granular material interface pressure measurement, the earth pressure cell with a d/d0 ratio exceeding 11 was recommended. The results obtained in this study provide theoretical foundation for energy saving and safety granary structure design.

Liquid Pressure Sensing System With Coupling RFID and HMM Based on Distance Measurement

Liquid pressure measuring is of increasingly importance to promote sustainable operation of civil and industrial equipment. In this paper, a novel approach based on distance measurement is proposed by using Radio Frequency Identification (RFID) and Hidden Markov Model (HMM). Two RFID tags, which interrogated by reader, are mainly used to build a liquid pressure sensing system (LPSS). At the same time, an ultra-high-frequency RFID chip with self-tuning capability aiming to achieve impedance matching is exploited. While HMM takes pride in its real-time processing and high efficiency so as to make a reasonable prediction of liquid pressure. The feasibility of proposed scheme is verified by double tags coupling circuit design and simulation. Through hardware construction and testing, reliable pressure measurement is achieved in an indoor scenario ( $0.5\textit {cm}\leq {d}\leq 7\textit {cm}$ ). Meanwhile, parameter evaluating model (PEM) and sequential estimation model (SEM), which are based on Maximum Likelihood Estimation (MLE) and HMM respectively, have been proposed to achieve online denoising.

New calibration procedure for differential pressure using twin pressure balances for flowrate measurement

Reliable pressure measurements are essential in all activities of society and industry. Indeed, the concern with traceability has notably improved and has received considerable interest due to the intensification of international trade, the need for environmental issues, safety and health requirements, for example in medical instruments, as well as devices for measuring the flow of Fluids Based on the pressure change. Differential pressure sensors are widely used in fluid flow processes, such as for monitoring the flow conditions and to determine flowrate or fluid velocity (example are the Pitot tube, Venturi, orifice plate etc.). This study focused on the precise generation of differential pressures in the range of 500 kPa to 20 MPa using gas-operated twin pressure balances. The metrological characteristics of a differential pressure manometer were evaluated.

信頼性の高い圧力測定のために―圧力の国家標準から現場の圧力測定まで―

信頼性の高い圧力測定のために―圧力の国家標準から現場の圧力測定まで―

Assessing Respiratory Function Depends on Mechanical Characteristics of Balloon Catheters

Respiratory muscle function and lung and chest wall mechanics are reliably assessed by esophageal and gastric balloon catheters. The aim of this in vitro bench study was to assess the mechanical properties of commercially available balloon catheters using an experimental model with 3 defined compliances (27, 54, 90 mL/cm H2O). Six catheters were investigated in 4 conditions: (1) balloon pressure during initial inflation, (2) static pressure measurements at different filling volumes, (3) estimation of set compliances in the experimental lung model at different levels of superimposed pressure, and (4) elastic balloon properties after 16 h of inflation. 5/6 catheters showed initial pressure artifacts resulting from material adhesion. All static pressure measurements could be performed with an error < 1 cm H2O. Balloon overfilling resulted in larger errors in 4/6 catheters. Compliance determined from pressure measurements via the catheters differed by < 5% from that determined from direct pressure measurements. Sixteen hours of inflation resulted in a broader working range, that is, overfilling effects occurred at higher filling volumes. The reliability of pressure measurements and estimation of the lung model's compliance in the tested catheters are high. Filling volume appears to be critical for precise pressure measurement and compliance estimation. At first use, adhesion of the balloon material might prevent reliable pressure measurement.

Reliability of pressure measurements via balloon catheters is high: an evaluation of six esophageal catheters

Reliable measurement of esophageal pressure is a prerequisite for analysis of respiratory system mechanics in spontaneous breathing patients. For that purpose, various types of balloon catheters exist that differ in material, size and shape. In physical models we studied the quality of pressure measurement via six different balloon catheters, three of them containing a second balloon for measurement of gastric pressure.

Macro-mechanical modeling of blast-wave mitigation in foams. Part II: reliability of pressure measurements

A phenomenological study of the process occurring when a plane shock wave reflected off an aqueous foam column filling the test section of a vertical shock tube has been undertaken. The experiments were conducted with initial shock wave Mach numbers in the range \(1.25\le {M}_\mathrm{s} \le 1.7\) and foam column heights in the range 100–450 mm. Miniature piezotrone circuit electronic pressure transducers were used to record the pressure histories upstream and alongside the foam column. The aim of these experiments was to find a simple way to eliminate a spatial averaging as an artifact of the pressure history recorded by the side-on transducer. For this purpose, we discuss first the common behaviors of the pressure traces in extended time scales. These observations evidently quantify the low frequency variations of the pressure field within the different flow domains of the shock tube. Thereafter, we focus on the fronts of the pressure signals, which, in turn, characterize the high-frequency response of the foam column to the shock wave impact. Since the front shape and the amplitude of the pressure signal most likely play a significant role in the foam destruction, phase changes and/or other physical factors, such as high capacity, viscosity, etc., the common practice of the data processing is revised and discussed in detail. Generally, side-on pressure measurements must be used with great caution when performed in wet aqueous foams, because the low sound speed is especially prone to this effect. Since the spatial averaged recorded pressure signals do not reproduce well the real behaviors of the pressure rise, the recorded shape of the shock wave front in the foam appears much thicker. It is also found that when a thin liquid film wet the sensing membrane, the transducer sensitivity was changed. As a result, the pressure recorded in the foam could exceed the real amplitude of the post-shock wave flow. A simple procedure, which allows correcting this imperfection, is discussed in detail.

Miniature Fabry-Perot pressure sensor created by using UV-molding process with an optical fiber based mold

We present a miniature Fabry-Perot pressure sensor fabricated at the tip of an optical fiber with a pre-written Bragg grating by using UV-molding polymer process. The mold is constructed by integrating an optical fiber of 80 μm diameter with a zirconia ferrule. The optical fiber based mold makes it possible to use optical aligning method to monitor the coupled intensity between the mold-side and replica-side fibers, rendering a maskless alignment process with a submicrometer accuracy. A polymer-metal composite thin diaphragm is employed as the pressure transducer. The overall sensor size is around 200 μm in diameter. Experimental study shows that the sensor exhibits a good linearity over a pressure range of 1.9-7.9 psi, with a sensitivity of 0.0106 μm/psi. The fiber Bragg grating is exploited for simultaneous temperature measurements or compensation for temperature effects in pressure readings. The sensor is expected to benefit many fronts that require miniature and inexpensive sensors for reliable pressure measurement, especially biomedical applications.

A comparative evaluation of three hydrophones and a numerical model in high intensity focused ultrasound fields

The pressure fields of two different high intensity focused ultrasound (HIFU) transducers operated in burst mode were measured at acoustical power levels of 25 and 50 W (continuous wave equivalent) with three different hydrophones: A fiber-optic displacement sensor, a commercial HIFU needle hydrophone, and a prototype of a membrane hydrophone with a protective coating against cavitation effects. Additionally, the fields were modeled using a freely available simulations software package. The measured waveforms, the peak pressure profiles, as well as the spatial-peak temporal-average intensities from the different devices and from the modeling are compared and possible reasons for differences are discussed. The results clearly show that reliable pressure measurements in HIFU fields remain a difficult task concerning both the reliability of the measured values and the robustness of the sensors used: Only the fiber-optic hydrophone survived all four exposure regimes and the measured spatial-peak temporal-average intensities varied by a factor of up to 1.5 between the measurements and the modeling and between the measurements among themselves.

Improvement of reliability in pressure measurements and international mutual recognition

Reliable pressure measurements provide the basis for all activities in society and industry, and every country shows considerable interest in them in international trade. Recently, characteristics of industrial digital pressure gauges and the short- and long-term stabilities as well as the stability under environmental change and during transportation have been improved remarkably. AIST focused its attention on the technological advancement, and, after evaluating the characteristics of digital pressure gauges in detail, incorporated them to some phases in the metrology system, which are the upgrading of national pressure standards, the international comparisons of the standards and the domestic traceability system. Consequently, the reliability of pressure measurements in industrial fields has been secured through an efficient process, and the international mutual recognition has been promoted by carrying out many international comparisons.

Pulsation Control in Pressure Metering Systems

Reliable pressure measurement in pulsating flow conditions is difficult. When an orifice meter is used, two significant errors can arise: the square root error, which is inherent to orifice plates, and the pressure distortion generated in the sensing lines and DP transmitter. This study is concerned with minimizing pulsation effects in the sensing-recording system. The method used involves predicting the system dynamic characteristic and modifying it so that pulsation excitation frequencies and the resonant frequencies of the system do not coincide. A differential pressure metering system is modelled as a acoustic-mechanical assembly that includes a DP transmitter equivalent piston, its cavities and sensing lines. The acoustic-mechanical interaction is shown for the pressure metering system incorporating a bellows type DP transmitter. The influence of the acoustic and mechanical parameters on the system dynamic characteristic is discussed.

Etude de 11 ventilateurs d'anesthésie : banc d'essai

Eleven anaesthesia ventilators were instrumentally tested under various conditions. They included : Excel and Modulus II Plus (Ohmeda) ; 710 and Servo anaesthesia circle 985 (Siemens) ; Jollytronic (Soxil) and Elsa (Engström) ; SA2 and Cicero (Dräger) ; ABT 4 300 (Kontron) ; Monnal A and the prototype Alys (Taema). The test circuit comprised a two compartment model lung, a pneumotachograph, a pressure gauge in the « airway . The volume was calculated as the integral of flow rate. Each machine was calibrated by the firms' technicians. Before each test, the pneumotachograph was calibrated using a 11 air syringe and the pressure gauge with a 5 cm water column. Each machine ventilated the model lung for 30 min before starting the tests. There were five tests : 1) reliability of the machine's spirometer, 2) reliability of the ventilation rate, 3) reliability of pressure measurements, 4) effect of increasing fresh gas flow on spirometry, 5) effect of increasing downstream resistances. In usual simulated ventilatory conditions, all the machines accurately delivered the setted ventilation and spirometric measurements were with minimal error only. Several ventilators (SA2, Excel, 710, Elsa, ABT 4 300) did not succeed in maintaining their performances when compliance was strongly decreased or resistance of the test lung notably increased. Resistance in the circuit during simulated spontaneous ventilation was < 3.6 cmH 2O · l −1 · s −1. Increasing fresh gas flow raised the minute volume delivered in six ventilators. It is concluded that, during extreme ventilatory conditions, the inspired volume must be adjusted so as to maintain the inspired tidal volume. However, ventilators which increase inspiratory time in response to an increased mechanical load cannot be adjusted by this way.

Reliability of pressure measurements: the EM ED F system

The reliability of foot pressure measurement using the EMED F system has been tested by recording 25 walks with 10 volunteer subjects at three different speeds. Coefficients of reliability calculated for 1–25 walks showed that a good level of reliability was achieved using one measurement for most force/pressure variables but when the mean result of three or more walks was used reliability was excellent. Measurements related to time were more variable than the total force, the peak pressure and the area. The total force and peak pressure were also shown to increase with increasing speed but this was not true for all sites on the foot.