Multi-channel Measurement System Research Articles

A Custom-Tailored Multichannel Pressure Monitoring System Designed for Experimental Surgical Model of Abdominal Compartment Syndrome.

In experimental medicine, a wide variety of sensory measurements are used. One of these is real-time precision pressure measurement. For comparative studies of the complex pathophysiology and surgical management of abdominal compartment syndrome, a multichannel pressure measurement system is essential. An important aspect is that this multichannel pressure measurement system should be able to monitor the pressure conditions in different tissue layers, and compartments, under different settings. We created a 12-channel positive-negative sensor system for simultaneous detection of pressure conditions in the abdominal cavity, the intestines, and the circulatory system. The same pressure sensor was used with different measurement ranges. In this paper, we describe the device and major experiences, advantages, and disadvantages. The sensory systems are capable of real-time, variable frequency sampling and data collection. It is also important to note that the pressure measurement system should be able to measure pressure with high sensitivity, independently of the filling medium (gas, liquid). The multichannel pressure measurement system we developed was well suited for abdominal compartment syndrome experiments and provided data for optimizing the method of negative pressure wound management. The system is also suitable for direct blood pressure measurement, making it appropriate for use in additional experimental surgical models.

Low-noise multi-channel underwater electric field measurement and analysis system for a ship model.

The underwater electric field (UEF) signature of a ship is a key factor in its survivability in marine warfare. Moreover, the study of a ship's UEF using scale models of ships in pools can be useful for the design of electromagnetically stealthy ships. Aiming at the system requirement of measuring and analyzing the UEF of scale models of ships with low noise, many channels, and real-time responsivity, we developed a system consisting of electrode sensors, a measuring device, and a personal computer (PC). Small Ag/AgCl electrodes with low noise and high stability were used. The measuring device was capable of simultaneously amplifying, sampling, and storing 24 channels of UEF data in real-time, and it was connected to the PC via Ethernet to facilitate the transfer of UEF data at high speeds. The PC software could display 24 low-frequency UEF curves in real time and perform spectral analysis and filtering of the UEF signals. In system performance tests, we found that the system had a noise floor lower than 6.34 nV/rt(Hz)@1Hz and could simultaneously sample 24 channels of UEF signals while storing, displaying, and analyzing the signals in real-time. The primary functions of the system were also validated in a pooled experiment.

A Tactile Sensing System Based on the Triboelectric Nanogenerator for Prosthetic Application

The distribution of interfacial stress between the amputee's residual limb and the prosthetic socket is thought to be directly related to comfort. Prosthetic sockets are custom-made and the current technology is very mature, whether, by manual molding or 3D scanning, the prosthesis can be made to fit the patient's residual limb, but when the patient actually wears the prosthesis, the wearer may still experience discomfort due to long wear time and foreign body friction. Therefore, researchers have been interested in quantifying these interfacial stresses in order to assess the extent of any potential damage to the residual limb and to reduce the cost of prosthetic fabrication by avoiding repetitive changes to the prosthesis. However, the existing pressure sensors are not only expensive but also have compatibility problems with the residual limb and are prone to instability under the influence of the external environment, which greatly affects the actual force readings in the area. Here, we developed a tactile sensor by triboelectric nanogenerator(TENG), which collects force energy by triboelectric effect, and its wide material selection, easy fabrication, and self-driving properties are receiving more and more attention. In our research, we propose to develop a multi-point array tactile sensor based on two materials: polydimethylsiloxane (PDMS) and polycaprolactone (PCL). The surface of PDMS has a droplet microstructure, and PCL is made into a nanofiber film by electrospinning to increase the specific surface area of the material in contact to improve the output characteristics of the device and achieve a larger detection range and sensitivity. In addition to the excellent durability at 10,000 cycles, the characteristics of the device also show good stability at different humidity and temperature. Finally, we integrated this multi-point array sensor with a multi-channel measurement system, attached it to the contact interface of a 3D-printed residual limb and prosthetic model, and collected real-time correspondence signals from the compressed side to demonstrate the feasibility of this application. We believe that this novel design offers a new approach to improve the comfort of prosthetic wear for amputees and has considerable potential.

A Multi-Channel Borehole Strain Measurement and Acquisition System Based on FPGA.

In this study, an FPGA(Field Programmable Gate Array)-based borehole strain measurement system was designed that makes extensive use of digital signal processing operations to replace analog circuits. Through the formidable operational capability of FPGA, the sampled data were filtered and denoised to improve the signal-to-noise ratios. Then, with the goal of not reducing observational accuracy, the signal amplification circuit was removed, the excitation voltage was reduced, and the dynamic range of the primary adjustments was expanded to 130 dB. The system's online compilation function made it more flexible to changes in measurement parameters, allowing it to adapt to various needs. In addition, the efficiency of the equipment use was enhanced. The actual observational results showed that this study's FPGA-based borehole strain measurement system had a voltage resolution higher than 1 μV. Clear solid tides were successfully recorded in low-frequency bands, and seismic wave strain was accurately recorded in high-frequency bands. The arrival times and seismic phases of the seismic waves S and P were clearly recorded, which met the requirements for geophysical field deformation observations. Therefore, the system proposed in this study is of major significance for future analyses of geophysical and crust deformation observations.

Design and Implementation of a Multi-Channel Temperature Measurement System Based on LabVIEW

As computer technology and instrument technology advance rapidly, both virtual instrument and Lab-VIEW have significantly grown. LabVIEW is extensively employed in the industrial and academic sectors for developing data acquisition systems, instrument control software, and analysis software. This paper presents the design of a multi-channel temperature measurement system based on a single-chip CPU and LabVIEW. The system consists of analog-to-digital conversion modules, temperature measurement modules, and data acquisition modules. The system uses the Nyquist-Shannon sampling theorem and the advantages of various digital filter types to obtain temperature uncertainty, including the compensation uncertainty of the reference junction. The system is of high quality in measuring accuracy, stability, scalability and other aspects. The complete system was inspected and verified using a superconducting magnetic energy storage device (SMES). The results demonized the ease of construction, practicality and precise regulation of the system. These results also show that temperature measurement devices are less than 0.1°C absolute error and are highly accurate, making them valuable for applications that require precise temperature measurements.

Design and Implementation of a Multi-Channel Temperature Measurement System Based on LabVIEW

Design and Implementation of a Multi-Channel Temperature Measurement System Based on LabVIEW

Customized Multichannel Measurement System for Microbial Fuel Cell Characterization.

This work presents the development of an automatic and customized measuring system employing sigma-delta analog-to-digital converters and transimpedance amplifiers for precise measurements of voltage and current signals generated by microbial fuel cells (MFCs). The system can perform multi-step discharge protocols to accurately measure the power output of MFCs, and has been calibrated to ensure high precision and low noise measurements. One of the key features of the proposed measuring system is its ability to conduct long-term measurements with variable time steps. Moreover, it is portable and cost-effective, making it ideal for use in laboratories without sophisticated bench instrumentation. The system is expandable, ranging from 2 to 12 channels by adding dual-channel boards, which allows for testing of multiple MFCs simultaneously. The functionality of the system was tested using a six-channel setup, and the results demonstrated its ability to detect and distinguish current signals from different MFCs with varying output characteristics. The power measurements obtained using the system also allow for the determination of the output resistance of the MFCs being tested. Overall, the developed measuring system is a useful tool for characterizing the performance of MFCs, and can be helpful in the optimization and development of sustainable energy production technologies.

CO2 and CH4 fluxes from forest soil in the northern Da Xing’anling Mountains in Northeast China during the freezing and thawing periods of near-surface soil in 2018–2019

ABSTRACT Under a warming climate, the studies on effects of seasonal freeze–thaw cycles on soil respiration are key to understanding the soil carbon cycles and ecosystem responses and resilience at mid- and high latitudes. In this study, the effluxes of soil surface CO2 and absorption rates of CH4 were measured in the Xing'an larch (Larix gmelinii) forest in the northern Da Xing’anling Mountains, Northeast China using an automatic multichannel soil greenhouse gas measurement system (dynamic gas chamber method) during the periods of October–November 2018 and April–May 2019. The results showed that during the freezing period of near-surface soil, CO2 and CH4 fluxes significantly declined, approaching zero, at the end of November. During the thawing period of near-surface soil, CO2 and CH4 fluxes from surface soil fluctuated markedly at first and then rose rapidly. The respective Q10 values of 3.86 and 4.89 during the freezing and thawing periods of near-surface soil, respectively, indicate the important role of ground freeze–thaw cycles in the modifications of CO2 and CH4 fluxes. The results of this study could help assess the stability of the soil carbon pool and carbon flux strength in taiga-forested permafrost regions in the northern Da Xing’anling Mountains, Northeast China.

Multi-channel phase measurement system for the space laser interferometry

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Synchronous Multipoint Low-Frequency EMI Measurement and Applications

Increased implementation of power electronics devices as well as high penetration of micro grids and embedded generation with low-supply inertia is resulting in grid stability problems, especially in transient or startup situations. The electromagnetic compatibility of these systems with regards to transients can be difficult to diagnose due to the short time duration and often intermittent nature of events. This letter proposes a multichannel measurement system which is able to measure voltage and current waveforms in multiple locations with synchronization and sample rates in the megahertz range. The overall design, characteristics, as well as applications are showcased in this letter.

SDR-Enabled Multichannel Real-Time Measurement System for In Situ EMF Exposure Evaluation

The spatial and temporal variability of the signals emitted by modern communication devices produced a paradigm shift in approaching the human exposure to electromagnetic fields (EMF). This inherent variability requires in situ, agile EMF measurement solutions capable of performing real-time isotropic measurements. The aim of this paper is to describe a new real-time, highly flexible multichannel EMF measurement system that consists of a sensor connected to state-of-the-art software-defined radio (SDR) equipment. In this paper an electric field sensor is proposed, but we also provide information on the extension of the probe to electric and magnetic fields. In the receiver section, the proposed solution is compared in terms of performances (sensitivity and accuracy), costs, and requirements, with standard solutions based on spectrum analyzers or a digital oscilloscope. Finally, the proposed solution was tested considering the signals emitted in various operating scenarios by a mobile device operating in the LTE-A and IEEE 802.11ax mobile communication standards. The results confirm the versatility and efficiency of the proposed solution for in situ EMF measurements of signals emitted by the new generation communication devices.

FPGA-based multi-channel thermocouple temperature measurement system

Aiming at the high and low temperature test requirements of spacecraft before being sent into space, this paper designs and implements a multi-channel thermocouple temperature measurement system based on FPGA.The system adopts thermocouple as temperature sensor, and ADT7310 is used as thermocouple cold junction temperature compensation, which solves the problem of thermocouple cold junction compensation better.The front end adopts AD7193, a 24-bit analog-to-digital converter with low noise, multi-channel and low power consumption, to amplify and A/D convert the signal at measuring junction of thermocouple.The control core is a field programmable logic gate array FPGA, which can better solve the problem of parallel processing of multi-channel temperature signals. At the same time, it uses the transposition method of the thermocouple standard graduation table, the interpolation look-up table algorithm and the cold junction compensation reverse look-up table algorithm, which is effective The temperature measurement accuracy of each channel is improved.The experimental results show that the system can be connected to 24 K-type or T-type thermocouple sensors, the measurement range can reach -200°C∼220°C (73.15K∼493.15K), and the relative error is less than ±0.3%F.S.

Development of a Multichannel Bioinstrumentation System for Human-Computer Interface Applications

A multi-channel measurement system used to measure electrocardiogram (ECG), electroencephalogram (EEG), electromyogram (EMG) and electrooculogram (EOG) biosignals has been designed and prototyped. The designed system has 16 configurable measurement channels. Of the 16 channels the developed system has, 8 have been designed for EEG, 2 for EMG, 2 for EOG, 1 for ECG measurements, the remaining 3 have been reserved as backup channels. In circuit design, biosignal amplifier design principles have been applied by taking into account the characteristics of the biosignal to be measured for each channel, such as bandwidth, frequency, amplitude, noise level. Modules such as instrumentation amplifier, filter, DC suppression unit, amplifier, DC level determination unit, analog-digital converter, optical isolation unit, power supply have been designed to perform biosignal measurements through these channels. Biosignals measured by the developed system can be shifted to the desired threshold level with the help of the analog output reference voltage, converted to digital data 10-bit resolution and transferred to the computer environment in real time. The data transferred to the computer can be used in C#, Excel, MATLAB, and LabVIEW platforms. The novelty of the developed system is that any of the four desired biosignal types can be measured from any channel. In addition, another feature of the system is that it can work with real-time data without being dependent on the databases serving for human-computer interface applications. In experimental studies with some researchers for the performance tests of the system, ECG, EEG, EMG and EOG signals have been recorded with different module configurations, and signal processing stages were carried out to be used for human-computer applications.

Multi-channel Optical Fiber EFPI Absolute Cavity Length Measurement System Based on FPGA Control and White-light Interference Technology

Multi-channel Optical Fiber EFPI Absolute Cavity Length Measurement System Based on FPGA Control and White-light Interference Technology

MULTICHANNEL FREQUENCY METER ON A PROGRAMMABLE LOGICAL INTEGRATED CIRCUIT FOR A RADIOMEASURING SYSTEM WITH FREQUENCY SENSORS

The paper presents the development of a multi-channel frequency measurement system on FPGA by Altera Cyclone IV, the main task of which is to measure the informative parameter of sensors of physical quantities with frequency output. Based on the analysis of existing multi-channel frequency measurement systems on the FPGA, it is established that it is advisable to use multi-channel frequency meters for simultaneous measurement of several frequencies. Unlike several frequency meters operating simultaneously, multi-channel frequency meters perform measurements in a single time base, which is provided by a common exemplary generator and timer. A multi-channel universal FPGA-based measuring device has been developed, which has 12 measuring channels for frequency output sensors and supports simultaneous operation of 127 digital sensors via I2C interface. Therefore, theoretically, data transmission from the developed device can be carried out wirelessly. The developed device can be connected to a personal computer via a UART-USB converter. As a chip for the implementation of the frequency meter is used FPGA company Altera EP4CE10F17C8 – a chip in the BGA case, which has 179 pins. The parameters, namely the value of the signal propagation delay, determine the maximum measured frequency, in our case about 3 ns (delay of the signal from the input to the internal register), which corresponds theoretically to 333 MHz. Specialized software has been developed to test the efficiency of a multi-channel measuring system for measuring informative parameters obtained from radio measuring transducers, based on the reactive properties of semiconductor structures with negative resistance. For convenience of perception, there is a visualization of the received information from the measuring device.

Research on vibration characteristics and Multi-parameter state recognition of ± 500 kV converter transformer under fluctuating conditions

The vibration of the winding and the iron core is the main source of the vibration of the converter transformer tank, and the vibration measurement and characteristic analysis are the judgment basis for its condition monitoring and identification. Compared with AC transformers, the vibration mechanism and vibration characteristics of converter transformers under fluctuating operating conditions are imperfect. Aiming at the special tank structure and considering the fluctuation of operating conditions, this paper establishes a multi-channel vibration measurement system for online identification of the operating status of the converter transformer, and extracts the characteristics parameters of the vibration signal in the time domain, frequency domain, and energy, and analyzes the differential distribution characteristics of winding vibration under different load currents, iron core vibration under different no-load voltages, and combined vibration during online rated operation. Finally, a method for identifying the operating status of converter transformers based on multi-characteristic parameters is proposed. The research results show that the characteristic parameters such as tank vibration intensity, maximum vibration frequency, and frequency band energy fluctuate with the operating status of the converter transformer, and there are obvious changes. Vibration measurement and characteristics of multi-characteristic parameters can be used to provide a theoretical basis and solution ideas for the operation status identification and early fault detection of converter transformers.

Multichannel gas electron multiplier based soft x-ray field-programmable gate array measurement system for W-Environment in Steady-state Tokamak (WEST): Hardware, installation, and first plasma acquisition.

The work describes a novel approach to the design of a fast, multichannel measurement system for plasma diagnostics [A. Wojenski et al., Fusion Eng. Des. 123, 727 (2016)]. Its main scope is to provide measurements of soft X-ray (SXR) emission during plasma phenomena at the W-Environment in Steady-state Tokamak (WEST), especially for monitoring and tracing tungsten impurities. This paper describes the vertical Gas Electron Multiplier (GEM) camera installed at the WEST [M. Chernyshova et al., J. Instrument. 10, P10022 (2015)]. The designed GEM detector readout board has more than 100 channels, resulting in high-performance requirements for the data acquisition and processing system. The novel system construction approach is that the unit works on the raw signals providing a high quality of the data, especially in the scope of pileup effect analysis. In the case of doubtful results, the source data can be easily reviewed offline. The data selection and transmission are done in Field-Programmable Gate Arrays (FPGAs) on the custom boards with the custom Peripheral Component Interconnect (PCI)-Express Gen2 switch that allows us to register signals from multiple FPGAs and then process the data by complex algorithms [G. Kasprowicz et al., J. Fusion Energy 38, 480 (2019)]. The firmware is replaceable and different working modes can be applied (some under verification): global trigger mode, high-speed data serialization, and extended signal registration. Low level optimized central processing unit software for data readout was also designed [P. Linczuk et al., J. Instrum. 14, C05001 (2019)]. The installation of the system is described due to complex system components' distribution. The first results of the successful acquisition of the plasma at the WEST are discussed. The corresponding SXR energy and topology spectra were computed. Those are the first technical measurements of the system to ensure verification of data quality.

Error Correction of Weak Current Measurement System Based on Wavelet Denoising and Generalized Regression Neural Network

Aiming at the problems that the weak current signal circuit is susceptible to noise interference and leakage current at the input terminal affects the measurement accuracy, a weak current measurement error correction scheme based on the combination of wavelet threshold denoising and generalized regression neural network (GRNN) was proposed. The scheme was applied to the error correction of multi-channel weak current measurement system based on the ADAS1134 chip: the wavelet threshold denoising was used to preprocess the original current data measured by the system and the current measurement value was corrected after the system measurement error correction model established with GRNN was constructed. Compared with the correction method based on least square method and back propagation neural network (BPNN), this method has many advantages such as high accuracy, anti-interference ability and strong generalization ability. The experimental results showed that RMSE=0.0911 nA, MAE=0.0354 nA, and MAPE=0.0078%, without increasing the complexity of the measurement circuit, which achieved the purpose of correcting the measurement error of the weak current measurement system.

High-Throughput Chiral Molecule Determination Based on Multi-Channel Weak Measurement

A multi-channel high-throughput chiral molecule determination method based on weak value amplification (WVA) is proposed for the first time. This method can be used for high-throughput and high-precision determination of chiral molecule. Through the design of multi-channel weak measurement system, we realized the real-time, high-throughput, high-sensitivity and high-resolution detection of chiral molecules by selecting proper measurement states. In this work, we have realized a sensitivity of 11.8 nm/° and a resolution of 3.13 × 10-4° for measuring optical rotation. Moreover, the proposed method is successfully applied for detection of lactose content in milk samples. Furthermore, the system has the advantages of simple and robust real-time detection settings, strong stability, high measurement efficiency and good scalability. This method has important significance in clinical diagnosis, food safety and biological system.

Multi-channel impedance measurement system for polymer humidity sensors

The design of a high performance, multi-channel impedance measurement system for humidity sensing characteristics test of polymer humidity sensors is presented. The relay modules with negligible contact resistance are designed to accomplish 32-channel measurement and automatic switching range. The division of the wide impedance range and the selection of the corresponding feedback resistance for automatic switching range are so designed as to satisfy the actual scale range of the ADC module for getting high accuracy measurement. An algorithm of compensation considering the parasitic parameters both in the measurement and feedback circuits is designed to further improve measurement accuracy. The whole measurement is automatically implemented by a field-programmable gate array for signal generation and logic calculation and a digital signal processor for frequency-spectra analysis. The results of the uncertainty analysis and tests revealed that our system was quite adequate to efficient humidity sensing characteristics test as opposed to the existing devices.