High-precision Pressure Sensor Research Articles

Gas state equation and flow mechanism of gas–liquid two-phase flow in airlift pump system

Airlift pumps (ALPs) have a simple structure and significant application potential. However, previous studies on ALPs have generally assumed that the gas density remains constant. In this paper, the gas state equation (GSE) for ALP is established based on the van der Waals formula, which explicitly considers the density of gas. An electrical resistance tomography system is used to collect the gas void fractions at different heights under different gas flow rates, and an empirical formula for the gas void fraction is established. To verify the effectiveness of the proposed model, high-precision pressure sensors and a high-speed camera are used alongside an electrical resistance tomography system to determine the realistic ALP flow parameters. The results of 409 sets of experiments show that: (1) the gas in ALP cannot be regarded as ideal gas, because the ideal GSE cannot distinguish between different gas flow rates; (2) the state change of gas in ALP is a quasi-equilibrium process, whereby the GSE of ALP can be obtained from the pressures under several locations; (3) the axial pressures predicted by the proposed GSE for ALP are in good agreement with experimental data; and (4) a single parameter of the GSE uniquely determines the state process. The proposed model and the experimental data provide a new methodology and comprehensive references for studying the working mechanism and efficiency of ALPs.

Data monitoring for indirect metering terminal of membrane gas measure device based on sensor network

In order to improve the data monitoring and information management capabilities of membrane gas measure device indirect metering terminals, a sensor network based data monitoring method for membrane gas measure device indirect metering terminals was proposed. The distributed and centralized sensor network node deployment method is used to achieve data collection for membrane gas measure device indirect metering terminals, and the collected membrane gas measure device indirect metering terminal data is segmented, fused, and reorganized. The distributed energy storage and constant volume two-level optimal control method is used to analyze the operation status of gas measure device indirect metering terminal data. The ZigBee networking protocol is used to build a network structure model for gas measure device indirect metering terminals, an integrated high-precision temperature and pressure sensor arranged parallel to the inner wall of the valve body is used to detect the temperature and pressure at the outlet of the membrane gas measure device. The temperature information is stored in DSP, and the user's expenses, system operation and maintenance, and peak shaving and valley filling benefits are taken as the parameters of the energy storage and constant volume outer layer model. The output stability of the indirect metering terminal data of the membrane gas measure device is analyzed in the high switching frequency mode. Combined with adaptive parameter adjustment, the indirect metering terminal control and data dynamic collection of the membrane gas measure device are realized. Realize dynamic monitoring of metering terminal data in wireless sensor network networking control mode. The test results show that using this method for indirect metering terminal data monitoring of gas measure devices has good output stability, strong dynamic fusion of sensing information, reduced metering errors, and improved metering accuracy of gas measure devices.

A High-Precision and Low-Power Capacitive Pressure Sensor Interface IC With Wireless Power and Data Transfer for a Pressure Sensor Implant

This article presents a system-on-a-chip (SoC) for pressure sensors in 180-nm CMOS technology. It can interface with a capacitive pressure sensor with an inductive wireless power supply and data transmission via load-shift keying (LSK). It integrates an analog front end (AFE), bandgap references (BGRs), delta-sigma ADC, I2C, RC oscillator, low-dropout regulators (LDOs), shorting control switches, and full-bridge rectifier (Rct). An external coil receives wireless power, which is rectified and regulated to 1.8 V by the full-bridge Rct and LDOs. The AFE samples the capacitance change of the pressure sensor to a voltage that is converted into 19-bit digital data by the delta-sigma ADC, which is then converted into 43 Hz per sample serial data by the I2C block. A temperature sensor is included, and 19-bit measurements are transmitted in serial with capacitance data. Serial data are transmitted wirelessly using LSK. This SoC has a measured accuracy of 1 mmHg between 575- and 900-mmHg absolute with a wireless power supply and wireless data transfer.

In-situ observation of seabed vertical deformation in Yellow River Delta under storm surges

Sediment destruction poses a major risk to marine engineering facilities in river delta areas. The vertical deformation of seabed induced by storm surges is one of the major causes of sediment destruction. In this study, an in-situ observation system for monitoring the seabed vertical deformation was developed. The system includes a Paroscienctific high-precision water pressure sensor, a tide & wave recorder, and an Acoustic Doppler Current Profiler (ADCP). A processing method of the high-precision water pressure data was established. The advantage of this data processing method is that it allows us to obtain the water depth variation in shallow sea area based on the observed water pressure data. The system and the processing method were applied in an in-situ observation, which was carried out in Chengdao Sea area in the Yellow River Delta from December 2020 to January 2021. During this observation, marine hydrodynamic changes and vertical deformation of seabed were synchronously monitored. Three storm surge events were observed during this period. The vertical deformation process of seabed during the storm surges was quantitatively analyzed. After the first two storm surge events, the monitored vertical settlement of seabed reached 8.97 mm. A seabed vertical deformation mechanism was established based on the in-situ monitoring data.

Analysis and performance assessment of the use of ammonia-based nano additive for lean combustion

In recent years, considerable progress has been made in exploring new applications of fuel additives to reduce emissions. Reduction of total nitrogen oxide (NOx) emissions can be achieved by decreasing the flame temperature by using fuel emulsified with water and/or using ammonia-based nano additives such as urea. The use of water as part of the hydrocarbon fuel is also one of the prospective directions in the development of new types of fuel systems. For the preparation of emulsified fuel, it is desirable to achieve greater stability of the emulsified fuel with minimum expenditure of chemicals and energy, so that the emulsified fuel can be used for a longer period. The paper analyzed the influence of nano-dispersed urea particles, water, and surfactant (Span 80/Tween 80) on the combustion stability and emission characteristics of aviation fuel. The experimental campaign was conducted on a test stand (a 300kW liquid vortex combustor of 300 kW) consisting of a cylindrical combustion chamber with four optical windows and equipped with high-precision pressure sensors, thermocouples, and an exhaust gas analyzer for acquiring emissions. The experimental campaign was conducted at a constant fuel/air ratio (Φ). One of the main focus is related to the stability of the emulsion. Chemiluminescence imaging was performed to characterize the effects of the additive on flame emissions. In addition, a statistical and spectral analysis was performed using the pressure sensor for instability analysis. Exhaust gas analysis was performed both with the additive described above and without additive for a constant Φ condition. The analysis was performed for NOx, carbon monoxide (CO) and carbon dioxide (CO2) and oxygen (O2).

High-Sensitivity Pressure Sensors Based on a Low Elastic Modulus Adhesive.

With the rapid development of intelligent applications, the demand for high-sensitivity pressure sensor is increasing. However, the simple and efficient preparation of an industrial high-sensitivity sensor is still a challenge. In this study, adhesives with different elastic moduli are used to bond pressure-sensitive elements of double-sided sensitive grids to prepare a highly sensitive and fatigue-resistant pressure sensor. It was observed that the low elastic modulus adhesive effectively produced tensile and compressive strains on both sides of the sensitive grids to induce greater strain transfer efficiency in the pressure sensor, thus improving its sensitivity. The sensitivity of the sensor was simulated by finite element analysis to verify that the low elastic modulus adhesive could enhance the sensitivity of the sensor up to 12%. The preparation of high-precision and fatigue-resistant pressure sensors based on low elastic modulus, double-sided sensitive grids makes their application more flexible and convenient, which is urgently needed in the miniaturization and integration electronics field.

High-Precision Optical Fiber Temperature and Pressure Sensor and Its Application in Production Wells

High-Precision Optical Fiber Temperature and Pressure Sensor and Its Application in Production Wells

The Cavitation-Induced Pressure Fluctuations in a Mixed-Flow Pump under Impeller Inflow Distortion

To reduce cavitation-induced pressure fluctuations in a mixed-flow pump under impeller inflow distortion, the dynamic pressure signal at different monitoring points of a mixed-flow pump with a dustpan-shaped inlet conduit under normal and critical cavitation conditions was collected using high-precision digital pressure sensors. Firstly, the nonuniformity of the impeller inflow caused by inlet conduit shape was characterized by the time–frequency-domain spectra and statistical characteristics of pressure fluctuation at four monitoring points (P4–P7) circumferentially distributed at the outlet of the inlet conduit. Then, the cavity distribution on the blade surface was captured by a stroboscope. Lastly, the characteristics of cavitation-induced pressure fluctuation were obtained by analyzing the time–frequency-domain spectra and statistical characteristic values of dynamic pressure signals at the impeller inlet (P1), guide vanes inlet (P2), and guide vanes outlet (P3). The results show that the flow distribution of impeller inflow is asymmetric. The pav values at P4 and P6 were the smallest and largest, respectively. Compared with normal conditions, the impeller inlet pressure is lower under critical cavitation conditions, which leads to low pav, pp-p and a main frequency amplitude at P1. In addition, the cavity covered the whole suction side under H = 13.6 m and 15.5 m, which led the pp-p and dominant frequency amplitude of pressure fluctuation at P2 and P3 under critical cavitation to be higher than that under normal conditions.

High-precision photonic crystal fiber-based pressure sensor with low-temperature sensitivity.

A novel high-precision photonic crystal fiber-based pressure sensor with low-temperature sensitivity is proposed. The sensor is fabricated by fusion splicing a photonic crystal fiber with a hollow core fiber immersed in polydimethylsiloxane. Owing to the special structure of the photonic crystal fiber, the temperature cross-coupling effect can be minimized and the membrane shape can be controlled. Experimental results indicate that the pressure sensitivity of the FP pressure sensor is 2.47 nm/kPa, 5.37 times the temperature sensitivity of 0.46 nm/°C. The proposed FP pressure sensor has broad application prospects in chemical and biological detection for monitoring pressure in real time.

An approach to gas sensors based on tunable diode laser incomplete saturated absorption spectra* *Project supported by the Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization (Grant No. 2013A061401005) and the Key Laboratory of Efficient and Clean Energy Utilization of Guangdong Higher Education Institutes (Grant No. KLB10004).

A spectral profile reconstruction method that can be applied to incomplete saturated-absorption spectra is proposed and demonstrated. Through simulation and theoretical calculation, it is proved that compared with the traditional whole-profile fitting method, this new method can increase the concentration detection upper limit of a single absorption line by about 8.7 times. High-concentration water vapor is measured using TDLAS technology, the total water vapor pressure and the self-broadened half-width coefficient of the spectrum were simultaneously measured from incomplete saturated-absorption spectra and compared with high-precision pressure sensors and the HITRAN databases. Their maximum relative deviations were about 4.63% and 9.10%, respectively. These results show that the spectral profile reconstruction method has great application potential for expanding the dynamic range of single-line measurements to higher concentrations, especially for in-situ online measurements under complex conditions, such as over large temperature and concentration dynamic ranges.

Analysis of Instability Mode and Limit Support Pressure of Shallow Tunnel Face in Sands

The stability analysis of the tunnel face is not only essential for guaranteeing the safe construction of urban shallow tunnels, but also directly affecting the influence degree of tunnel construction on nearby structures. The primary concerns in the stability analysis of the tunnel face are the instability mode of surrounding rocks and the limit support pressure on the tunnel face. In this paper, face stability of shallow tunnels in sands was conducted using a symmetrical model test. The ground surface settlement, support pressure on the tunnel face and progressive instability modes of sands at tunnel face are measured by using an LVDT (Linear Variable Differential Transformer) displacement sensor, high-precision pressure sensor and high-definition digital camera, respectively. The test results indicate that the shear failure band appears in sands in front of the tunnel face and develops from the tunnel invert to the tunnel crown. The upper sands undergo stress redistribution, and the pressure arch appears with initial form of “ellipsoid”, then of the “pyramid”. Moreover, the support pressure on the tunnel face experiences four stages, namely, rapid decline stage, the minimum stage, slowly raises stage and stable stage during tunnel excavation. The research results of this paper will provide theoretical support for the reasonable value of the support pressure on the tunnel face in practical engineering.

Experimental study on integrated and autonomous conductivity-temperature-depth (CTD) sensor applied for underwater glider

This paper studies a novel CTD sensor (SZQ1-1) which is developed for underwater glider to meet the requirement of autonomous acquisition of high-quality profile hydrodynamic oceanography data. An independently developed electromagnetic induction type conductivity sensor, a quick response thermistor and a high-precision pressure sensor is used to integrate the CTD sensor. Several designs of compact mechanical structure and low-power control acquisition circuit are developed in the CTD sensor. The SZQ1-1 CTD is calibrated with measuring instrument in the laboratory and fourth-degree polynomial fitting equations are developed to fit the curves. After software-based calibration, the SZQ1-1 is compared with SBE 19plus by sea trial. The SZQ1-1 and SBE 19plus were carried by an underwater glider which dived in Northern South China Sea with a maximum depth of 500.36 m. Because the thermal lag error exists in the original data measured with the CTD sensor in the underwater glider, the measured conductivity and salinity data are revised again in the software. According to sea trial results, the real-time temperature, salinity and depth profile data obtained by SZQ1-1 sensor is consistent with the data measured with SBE 19plus.

Potential of Pressure Sensor Based Mass Estimation Methods for Electric Buses

One approach to improve the economic efficiency of trolleybuses in the so-called BOB Project in the German town of Solingen is to use them as mobile energy storages in a smart grid. To achieve this, reliable information on available energy is essential, which in turn needs to be derived from a precise range calculator. As shown in this article, vehicle mass is a strong influencing factor, especially in urban traffic. Depending on passenger volume, the total mass and range of the bus varies by about 30 percent. The currently available mass on the bus fluctuates by more than 2 tons for constant payloads, and there is no proven solution for a more accurate mass estimation for buses in public passenger transportation. Therefore, this article presents a viable methodology to detect changes in payload, using high precision pressure sensors on the bus’s tires and air suspensions. These mass inducted pressure changes are extracted from the measurement data, using a filter to be later converted back into the corresponding masses. As the article will show, both approaches have their respective advantages and disadvantages, but have high potential and should therefore be investigated further.

A new laboratory protocol to study the plugging and sand control performance of sand control screens

Sand retaining media plugging in sand control wells has become a common and urgent problem in the oil and gas industry. Yet, no unified analysis or industry standards on the evaluation of the sand retaining media has been reported recently.In this paper, a systematic approach was presented to investigate the performance of sand control screens. A series of tasks were performed, including the processing of sand control simulation unit, the analysis of formation parameters such as the size of formation sand and reservoir fluid viscosity, the determining of pressure drop through the sand retaining medium, the calculation of oil-production index and so on.The importance of using the sand control unit was clearly demonstrated. The pressure drop along block sand media was determined in three different positions simultaneously with the high precision pressure sensor. The process of forming the sand bridge was recorded for all tests using a Digital Camera. The oil-production index and permeability of the sand control screen were calculated based on the flow rate and pressure drop. An electron microscope was conducted to observe the plugging of the sand control screens. This process is conducive to analyze the clogging process of sand control screens and optimize the design of sand control parameters. The amount and particle size distribution of sand produced and sand arch also were determined. These parameters are very important to the sand control properties of sand control screens. A set of novel sand control physical simulation experiment device was introduced to measure the above parameters. The measurement techniques and procedures presented in this paper provide a standard measurement protocol for the characterization of different sand control screens. The result of a case test shows that the new test method presented in this paper can effectively improve the drawbacks of existing methods.

Polymer-Assisted Pressure Sensor with Piezoresistive Suspended Graphene and Its Temperature Characteristics

A polymer-assisted pressure sensor with piezoresistive suspended graphene is proposed and fabricated with high yield. Our sensor exhibits a good pressure response comparable to that of commercial sensors. The sensitivity is estimated to be [Formula: see text][Formula: see text]kPa[Formula: see text], higher than that of similar Si-based pressure sensors. The influence of the temperature on the sensor performance is systematically analyzed. An inverse temperature response is observed, and a nonnegligible temperature effect on the sensor resistance is demonstrated. Considering the temperature-induced cavity pressure change, a new temperature–resistance model is built to explain the nonlinearity of the sensor response to the temperature variation. Experiments under different test voltages show the influence of the current thermal effect, which is similar to that of temperature and nonnegligible for high-precision pressure sensors. Our new sensor holds great potential for practical application, and the findings on the temperature characteristics open up a route to further improve the sensor performance.

An intelligent dental robot

ABSTRACTAn intelligent dental robot (IDR) is reported for the purpose of artificial denture verification and test. Methods: The IDR is composed of power system, intelligent control and driving system, sensor system and supporting system. Five Maxon motors are adopted to provide the driving force for the IDR. Novel motor linear actuators are developed to mimic the movement of human’s masticatory muscles. Forward and inverse kinematics of the IDR are analyzed. Seven high-precision pressure sensors are utilized to detect the force on individual artificial tooth. Results: Motion and force experiments are conducted on the IDR. The maximum biting force provided by the IDR is 490 N. Hysteresis rate of the biting force loading and unloading is less than 3%. The largest displacement for the mandible movement test is found to be 60, 9 and 22 mm in the vertical, protrusive and lateral directions, respectively. Conclusion: IDR can complete simulated human masticatory movement and provide sufficient biting force. Significance: The IDR provides clinical guidance for the design and performance test of artificial denture.

In Situ Mass Spectrometry Studies of Gas Evolution Reactions During Cell Cycling in Aqueous Lithium Ion Batteries

In terms of safety, toxicity, cost and manufacturing simplicity, lithium ion batteries with aqueous electrolytes offer significant advantages over their non-aqueous counterparts. Despite these advantages, a low thermodynamic stability window of water (1.23 V, 2.62 V to 3.85 V vs. Li+/Li at pH 7) yields a low cell voltage, hence a low energy density system as compared to state-of-the-art non-aqueous Li-ion batteries. However, recent ‘water in salt’ (WiS),1 ‘water in bisalt’ (WiBS)2 and ‘hydrate melt’3 electrolytes widen the electrochemical stability window of water from 1.23V to >3.0V (~1.8 V to 5.0 V vs. Li+/Li), which results an energy density >100 Wh/kg when coupled a S-anode to a LiMn2O4 cathode.4 While these reports highlight impressive overall cell performances,1-4 gas evolution analyses of H2 at anode via HER and O2 at cathode via OER, or any other gas producing parasitic reaction, e.g. Li2S + 2H2O → H2S + 2LiOH @ S-anode, are not adequately addressed. At Liox, we anticipate that H2 and O2 generation from water electrolysis, or any other gas generating parasitic reaction would be detrimental to overall cell performance, and severely limit their ability to be practical and safe energy storage systems. To validate this conjecture, we have designed a special hermetically sealed Swagelok cell with known volume, comprising a high precision pressure sensor (Omega) and a three way Valco valve which can easily be connected to a high resolution mass spectrometer for qualitative and quantitative - in situ or ex situ - analysis of evolved gases during cell operation. We have tested a number of cathode and anode active materials – such as LFP, LMO, NMC, NCA, LCO, S, LTO, C-TiO2, etc. in the hermetically sealed cell. To study the cathode and anode separately, we assembled a series of symmetric cells; either cathode/cathode for OER or anode/anode for HER, and cycled them to monitor pressure changes, and identify and quantify the evolved gases by high precision RGA mass spectrometer. In this presentation, a series of symmetric and full-cell cycling data (>300 cycles) to discern gas evolving parasitic side reactions, pressure changes during cell operation, in situ and ex situ mass spectrometric analysis of evolved gases will be discussed.

Development of a new bench for puncturing of irradiated fuel rods in STAR hot laboratory

A new device for puncturing of irradiated fuel rods in commercial power plants has been designed by Fuel Research Department of CEA Cadarache in order to provide experimental data of high precision on fuel pins with various designs. It will replace the current set-up that has been used since 1998 in hot cell 2 of STAR facility with more than 200 rod puncturing experiments. Based on this consistent experimental feedback, the heavy-duty technique of rod perforation by clad punching has been preserved for the new bench. The method of double expansion of rod gases is also retained since it allows upgrading the confidence interval of volumetric results obtained from rod puncturing. Furthermore, many evolutions have been introduced in the new design in order to improve its reliability, to make the maintenance easier by remote handling and to reduce experimental uncertainties. Tightness components have been studied with Sealing Laboratory Maestral at Pierrelatte so as to make them able to work under mixed pressure conditions (from vacuum at 10-5 mbar up to pressure at 50 bars) and to lengthen their lifetime under permanent gamma irradiation in hot cell. Bench ergonomics has been optimized to make its operating by remote handling easier and to secure the critical phases of a puncturing experiment. A high pressure gas line equipped with high precision pressure sensors out of cell can be connected to the bench in cell for calibration purposes. Uncertainty analyses using Monte Carlo calculations have been performed in order to optimize capacity of the different volumes of the apparatus according to volumetric characteristics of the rod to be punctured. At last this device is composed of independent modules which allow puncturing fuel pins out of different geometries (PWR, BWR, VVER). After leak tests of the device and remote handling simulation in a mock-up cell, several punctures of calibrated specimens have been performed in 2016. The bench will be implemented soon in hot cell 2 of STAR facility for final qualification tests. PWR rod punctures are already planned for 2018.

Identification and Elimination of Hygro-Thermo- Mechanical Stress-Effects in a High-Precision MEMS Pressure Sensor

A micromechanical pressure sensor has been modeled and characterized with a focus on hygro-thermo-mechanical stress originating from a thermoset-polymer die-attach material, and its influence on the sensor output signal. The sensor output signal shows a first-cycle effect during the first thermal cycle after storage, as well as increased hygro-thermal hysteresis. Whereas such effects are normally difficult to explain quantitatively, our model of hygroscopic diffusion and swelling provides an excellent match with experimental values. By implementing suitable stress-isolating structures in the sensor design, the effect of thermoset polymer stress on the sensor output signal can be reduced to non-detectable levels. The resulting sensor designs shows improved performance with a reduced signal drift and hygro-thermal hysteresis. [2016-0281]

Study on sapphire microstructure processing technology based on wet etching

Aiming at the problem that sapphire surface roughness is quite large after wet etching in sapphire microstructure processing technology, we optimize the wet etching process parameters, study on the influences of concentration and temperature of etching solution and etching time on the sapphire surface roughness and etching rate, choose different process parameters for the experiment and test and analyze the sapphire results after wet etching. Aiming at test results, we also optimize the process parameters and do experiment. Experimental results show that, after optimizing the parameters of etching solution, surface roughness of etched sapphire is 0.39 nm, effectively with reduced surface roughness, improved light extraction efficiency and meeting the production requirements of high-precision optical pressure sensor.