Synchronous Detection Research Articles

A 64 × 1 Multi-Mode Linear Single-Photon Avalanche Detector with Storage and Shift Reuse in Histogram

Single-photon avalanche detectors (SPADs) have significant applications in fields such as autonomous driving. However, processing massive amounts of background data requires substantial storage and computational resources. This paper designs a linear SPAD sensor capable of three detection modes: 2D intensity detection, 3D synchronous detection, and 3D asynchronous detection. A configurable coincidence circuit is used to effectively suppress background light. To overcome the significant resource demands for storage and computation, this paper designs a histogram circuit that simultaneously possesses data storage and shifting capabilities. This circuit can not only perform statistical counting on time data but also shift data to quickly complete computational analysis. The chip is fabricated using a 0.13 μm mixed-signal CMOS process, with a pixel scale of 64 elements, a time resolution of 132 ps, and a power consumption of 12.9 mW. Test results indicate that the chip has good detection capabilities and good background light suppression. When the background light intensity is 6000 lux, the maximum background data are suppressed by 95.4%, and the average suppression rate increases to 86% as the coincidence threshold is raised from 0 to 1.

A sensitized dual-response ratiometric fluorescent sensor integrated smartphone platform for accurate discrimination and detection of tetracycline homologues based on N-CDs‒Eu3+ complex.

Asensitized dual-response ratiometric fluorescent sensor integrated smartphone platform for accurate discrimination and detection of tetracycline(TC) homologues was fabricated based on N-CDs-Eu3+ complex. In the sensing system, N-CDs act as a sensitizer of Eu3+ and significantly enhance the fluorescence of TC-Eu3+ complex approximate 40-fold owing to the synergistic effect of antenna effect (AE) and fluorescence resonance energy transfer (FRET). A paper sensor integrated with a smartphone platform is further fabricated for on-site measurement of TC. The proposed sensing platform exhibits an obvious color change from blue to red with limit of detection (LOD) of 1.5 and 63.2 nM for spectrofluorimetry and paper sensor, respectively. In addition, to eliminate the interference from TC homologues, a simple and effective sensor array was constructed by regulating thepH of the system. The different fluorescence responses to four tetracycline homologues used widely (TC, OTC, CTC, and DOX) were examined and dealt with principal component analysis, and accurate differentiation of TC homologues was therefore achieved. This work provides an integrated method for identification and synchronous quantitative detection of TCs, and a potential application for visual and on-site detection of TCs in environmental monitoring and food safety.

A robust time synchronization algorithm for GNSS/IMU integrated navigation in urban environments

Abstract Global navigation satellite systems (GNSS) are often integrated with inertial measurement units (IMU) for navigation in urban environments. The ability of these integrated systems to achieve precise positioning and navigation is highly dependent on accurate time synchronization. While the current time synchronization algorithms are capable of achieving millisecond-level synchronization in open environments, their performance deteriorates significantly in complex urban environments due to the impact on GNSS measurements of non-line-of-sight (NLOS) signals and multipath effects. Here we propose a loosely coupled GNSS/IMU integration time synchronization error modeling and compensation algorithm to tackle this problem in the context of urban vehicle navigation. In the algorithm, the time synchronization error is augmented as a state variable in the Robust Extended Kalman Filter (REKF), with the robustness factor threshold being dynamically adjusted based on the time synchronization error. Furthermore, we have designed a system time synchronization detection scheme based on two detection factors, with the aim of achieving high-precision GNSS/IMU time synchronization in complex urban environments. Experimental results show that the proposed algorithm synchronizes data time to the millisecond level in urban positioning environments. This represents an improvement of more than 90% in time synchronization precision compared to the traditional EKF-based time synchronization algorithm, and an improvement of more than 60% compared to the REKF-based time synchronization algorithm. Furthermore, compared to the EKF-based GNSS/IMU fusion algorithm, the proposed algorithm enhances the accuracy of the determination of both position and velocity in the horizontal and 3D directions by more than 50% and heading accuracy by 85%.

ADALINE-based synchronous detection for enhanced shunt APF performance

Power quality issues caused by current harmonics from nonlinear and unbalanced loads are a growing concern. This paper presents a novel control strategy for four-wire shunt active power filters (SAPF) that surpasses existing conventional methods in mitigating harmonics and power factor correction. The strategy employs an improved synchronous detection method (SDM) enhanced by an adaptive linear neural network (ADALINE) trained using the least mean square (LMS) algorithm. This approach accurately estimates harmonic frequencies, enabling the SAPF to generate precise compensation currents. The effectiveness of the proposed method is validated through MATLAB-Simulink simulations under balanced supply conditions, encompassing diverse load scenarios. These simulation results are compared with those obtained using instantaneous power theory (IPT). They demonstrate the ability of the proposed method to achieve excellent harmonic identification and elimination, to comply with IEEE 519 harmonic limits, to ensure sinusoidal and balanced line currents, and to compensate for reactive power and neutral current. Furthermore, its simple architecture and noise robustness make it a promising solution for enhancing power quality.

Synchronous detection of multiple micro-substances with a single output channel using a weakly coupled resonator array

Abstract In this paper, a multiple micro-substances sensing scheme with a single output channel using a weakly coupled resonator array is proposed. An analytical model of the resonator using the Euler-Bernoulli beam theory has been developed, as well as the dynamic behavior has been further explored using the Galerkin method. We have discovered numerically that, in the weakly coupled cantilever array, the A-f (amplitude-frequency) curve of any cantilever physically reflects the vibration features of other cantilevers. Hence, by measuring the output signal of a single cantilever, multiple substances applied on each cantilever respectively can be identified and detected synchronously. A single output channel via a weakly coupled micro-resonator array is constructed and validated numerically for picogram level mass detection. Equivalent experiments with a macro coupled five-cantilever array have been further conducted for verification. Under a common sweep-driven signal, the five analytes applied on each cantilever with masses at microgram level can be detected synchronously and independently by measuring the frequency shifts of the five resonant peaks of the center cantilever. Multiple substances sensing with a single output channel and a single driving signal is thus realized with low relative errors and high linearities. By enhancing the driving voltage, the mass resolution can also be improved via Duffing bifurcation. This work not only reveals a new coupled vibration behavior but also provides a new avenue for multiple analytes detection.

Intelligent islanding detection in smart microgrids using variance autocorrelation function‐based modal current envelope

AbstractIslanding detection is a critical issue in grid‐connected distributed microgrid systems. Distributed generation in the current power system has caused many challenges. Consequently, detecting quick and effective islanding is the most critical issue to minimise equipment failure, avoid danger, and maintain grid safety. There are various techniques for islanding identification in microgrids. Three classifications have been applied to categorise these strategies, which are: active, passive, and hybrid. This paper proposes and demonstrates an efficient and accurate approach to islanding detection based on the Variance Autocorrelation Function of a Modal Current Envelope (VAMCE) technique. Demodulation techniques including synchronous real demodulation, square law demodulation, asynchronous complex square law demodulation, and the quadrature demodulation technique are employed to detect the envelope of the 3‐phase current signal. The VAMCE methodology is better suited for islanding detection because of its response to current sensitivity under islanding scenarios but not under normal conditions. Several simulations under various settings, including normal and islanded scenarios are used to analyse this method. These simulations have demonstrated different situations, such as when the system works normally and when it does not. The VAMCE along with the quadrature demodulation technique outperforms the others. The proposed solution is not only more accurate but also much faster compared to other methods. The proposed approach can identify normal and islanded situations in just 0.4 s.

Multi-Channel Differential Synchronous Demodulator for Linear Inductive Position Sensor

Multi-Channel Differential Synchronous Demodulator for Linear Inductive Position Sensor

Protease-activatable nanoprobe based on peptide decorated titanium carbide engineering for synchronous monitoring of cancer biomarkers with different spatial distributions

Synchronous monitoring of multiple biomarkers with different spatial distributions in tumor microenvironment is crucial for auxiliary staging diagnosis and objective evaluation of cancer progression. Herein, sequentially protease-activatable fluorescent sensing nanoprobe (Ti3C2@Dual-Pep-Lipid) based on Ti3C2 MXene and fluorochrome-labelled peptide was constructed to achieve the synchronous detection and imaging of extracellular MMP-2 and intracellular CTSB. The fluorescence signals of Ti3C2@Dual-Pep-Lipid nanoprobe maintained quenched and could be turned on via the specific cleavage of peptides by active MMP-2 and CTSB, respectively. Hence, Ti3C2@Dual-Pep-Lipid nanoprobe can respond the extracellular MMP-2 and intracellular CTSB in lysosome sequentially to turn on the green and red fluorescence to achieve the synchronous detection of two biomarkers with different spatial distribution. Besides, the nanoprobe could monitor MMP-2 and CTSB accurately at 2D cell monolayers and 3D multicellular spheroids, and distinguish tumor cells and non-tumor cells. Additionally, the nanoprobe exhibited the capacity of tracing biomarkers in infected cells delivered by cancer cell exosomes. Consequently, the synchronous imaging of MMP-2 and CTSB in vivo was achieved using the nanoprobe. This strategy of the synchronous detection of two biomarkers with different spatial distributions in tumor microenvironment may provide more comprehensive information for improving cancer diagnosis effect.

Fluorescence resonance energy transfer system coupled with photonic crystals labeling strategy for multiplexed detection of microRNAs from breast cancer

MicroRNAs (miRNAs) play a crucial role in post-transcriptional gene expression and freely circulate in the body. Dysregulation of miRNA signaling is associated with various diseases, including breast cancer (BC). The miRNA profiles from liquid biopsies offer a promising strategy for cancer diagnosis, prognosis and monitoring. Particularly, the simultaneous profiling of multiple miRNA levels greatly enhances the accuracy of cancer diagnosis. In this study, photonic crystals (PhCs) serve as both labels and carriers enabling synchronous optical detection of multiple miRNA targets overexpressed in BC. The process is achieved by triggering enzyme-free amplification reactions through target interactions, generating fluorescence resonance energy transfer (FRET). The method offers high sensitivity, sequence specificity, and the capability to detect multiple targets. The limits of detection (LOD) of the sensor for miRNA-21, miRNA-155 and miRNA-10b were 6.36 fM, 8.52 fM and 6.06 fM, respectively. Moreover, the sensor can be directly applied to untreated human serum with a minimal sample volume requirement of only 1 μL. The simultaneous detection of miRNAs in clinical serum samples from healthy individuals and BC patients was carried out. The results show that the average relative expression levels of miRNA-21, miRNA-155 and miRNA-10b in the BC patient group were 12.18 ± 3.20, 17.27 ± 2.17 and 12.17 ± 1.59 times that of the healthy group, respectively. Therefore, the developed multi-detection strategy can precisely identify these cancer biomarkers and offer a crucial pathway for minimally invasive cancer diagnostics, cancer prevention, early intervention and treatment.

Research on ultrasonic synchronous detection method for material residual stress and thickness

Being limited to the different transmission and reception modes and detection signals of the critical refracted longitudinal wave method for stress measurement and the perpendicular incident echo method for thickness measurement, it is necessary to use different probes and equipments when simultaneously measuring stress and thickness. For this difficulty, the acquisition frequency and the number of bits are taken as the research object to realize the optimization of the echo signal. By combining FEM simulations with Comsol software with experimental research, the effects of probe incidence angle, probe spacing, and temperature on ultrasonic waves are investigated, and the relationship between probe spacing and the stress coefficient of measured component (K) is analyzed. A novel ultrasonic synchronous detection method for residual stress and thickness is proposed. This method is based on an integrated transmit-receive probe with oblique incidence, utilizing critical refracted longitudinal wave (LCR wave) for stress detection and synchronously generated transverse waves for thickness measurement. For the first time, a formula for ultrasonic thickness measurement based on inclined incidence is derived. Using self-developed equipment, ultrasonic testing experiments on step test block and cantilever beam loading device were conducted to verify the accuracy and precision of the proposed synchronous detection method for stress and thickness. This method has significant application prospects in the inspection or online monitoring of pressure vessels concerned with fatigue and corrosion performance.

Development and Design of an Online Quality Inspection System for Electric Car Seats.

As the market share of electric vehicles continues to rise, consumer demands for comfort within the vehicle interior have also increased. The noise generated by electric seats during operation has become one of the primary sources of in-cabin noise. However, the offline detection methods for electric seat noise severely limit production capacity. To address this issue, this paper presents an online quality inspection system for automotive electric seats, developed using LabVIEW. This system is capable of simultaneously detecting both the noise and electrical functions of electric seats, thereby resolving problems associated with multiple detection processes and low integration levels that affect production efficiency on the assembly line. The system employs NI boards (9250 + 9182) to collect noise data, while communication between LabVIEW and the Programmable Logic Controller (PLC) allows for programmed control of the seat motor to gather motor current. Additionally, a supervisory computer was developed to process the collected data, which includes generating frequency and time-domain graphs, conducting data analysis and evaluation, and performing database queries. By being co-located with the production line, the system features a highly integrated hardware and software design that facilitates the online synchronous detection of noise performance and electrical functions in automotive electric seats, effectively streamlining the detection process and enhancing overall integration. Practical verification results indicate that the system improves the production line cycle time by 34.84%, enabling rapid and accurate identification of non-conforming items in the seat motor, with a detection time of less than 86 s, thereby meeting the quality inspection needs for automotive electric seats.

Multimodal spatiotemporal drug assessment platform based on a microelectrode neural network chip in Alzheimer’s disease

The pathogenesis of Alzheimer’s disease (AD) remains elusive. The development of new drugs is protracted, costly, and fraught with failure, largely due to the lack of convenient methods for dynamically studying the pathogenesis of AD and evaluating drug efficacy in vitro. There is a dearth of in vitro multi-site assay platforms capable of observing the therapeutic effects of AD drugs at the level of cellular and network. Consequently, an in vitro multimodal spatiotemporal drug assessment platform has been developed based on a neuronal network chip. It has a symmetric distribution of electrode points with two different sizes (10 μm and 30 μm), which are more suitable for the detection of neuronal connections. The multifaceted neurophysiological properties, including single neuron firing pattern, intercellular connection, transmission speed, and neural network communication, were detected in real time. The results demonstrated that the differences between experimental groups in electrophysiological properties, could significantly distinguish the effects of AD representative drug treatment after different levels of neurological injury. The administration of the drug at the initial stage of β-amyloid oligomers (AβOs) toxicity was found to effectively retard the deterioration of neurons and network (early stage: firing rate increased by 8 %; middle stage: cross-correlation coefficient decreased by 27 %; late stage: similarity index remained positive and relative transmission speed decreased by 11 %). The neurophysiological mechanism of drug interaction was further elucidated, which may provide the guidance for the optimal timing of drug administration. Following the further extension of biosensor longevity and the expansion of synchronous multidimensional parameter detection, including impedance and electrochemistry, it is anticipated that this will become a novel platform for the preclinical evaluation and screening of AD drugs.

Research on Ultrasonic Synchronous Detection Method for Material Residual Stress and Thickness

Research on Ultrasonic Synchronous Detection Method for Material Residual Stress and Thickness

Zero-dimensional lead telluride quantum dots optical modulator for red Pr:YLF ultrashort pulse laser

High-quality lead telluride quantum dots (PbTe QDs) are prepared by a top-down liquid phase exfoliation (LPE) method successfully and used as a novel saturable absorber (SA) to first realize a picosecond continuous-wave mode-locked (CWML) red laser with a Pr:YLF crystal. The nonlinear optical saturable characteristic of the PbTe QDs SA is measured by applying a double-channel synchronous detection technique. Further, a picosecond CWML Pr:YLF laser with a highest average output power of 115 mW is obtained, corresponding to a pulse energy of 1.5 nJ and a peak power of 24.2 W. These findings indicate that high-quality PbTe QDs SA is an effective optical modulator, demonstrating its application prospects in the field of visible ultrafast photonics.

Internal inspection method for crack defects in ferromagnetic pipelines under remanent magnetization

Magnetic flux leakage (MFL) testing is effective in detecting corrosion in ferromagnetic pipelines. However, the MFL generated at the crack is highly weak and is easily drowned in the strong background magnetic field and difficult to detect. Therefore, this paper creatively proposes a remanent magnetic flux leakage (RMFL) detection method. This method utilizes the hysteresis state of the pipeline after MFL detection and identifies crack defects by collecting the remanent magnetic flux density near the inner wall surface of the pipeline. The remanent magnetic field distribution near the pipeline surface is examined at different crack sizes, magnetization speeds, and lift-off values via theoretical analysis, finite element simulation, and experimental verification. In addition, experiments have demonstrated that in terms of crack detection capability, RMFL is superior to MFL. Therefore, adding a RMFL measurement module to the conventional MFL detector has important practical value. It can realize the targeted collaborative application of these two technologies, namely the synchronous detection of corrosion and crack defects, which greatly improves the detection coverage and detection efficiency.

Frequency of hepatitis D virus with different hepatitis B virus serological markers and coinfections in hospital patients from Argentina: synchronous testing of anti-HDV antibodies and HDV RNA.

Hepatitis D virus (HDV) RNA-positive cases with total anti-HDV antibodies nonreactive were documented. Moreover, HDV infection was observed in subjects with occult hepatitis B virus infection. The prevalence of HDV infection in Argentina is low; however, further research in different populations is needed. This study aimed to perform synchronous HDV detection in reactive hepatitis B virus patients treated in a public hospital in the province of Buenos Aires, Argentina, some of whom were coinfected with hepatitis C virus and/or HIV. A total of 189 hepatitis B virus-reactive serum samples with or without hepatitis C virus and/or HIV coinfection were synchronously analyzed for anti-HDV antibodies and HDV RNA. HDV prevalence was 4.2% with HDV RNA found in 61 samples, most of which were nonreactive to anti-HDV antibodies and hepatitis B surface antigen. Genotype 1 was identified in all HDV sequences. Moreover, triple and quadruple infections were observed, showing a high frequency of HDV infection in hospitalized patients not following the recommended diagnostic algorithm. This study is evidence that the synchronous testing of anti-HDV antibodies and HDV RNA is necessary for the diagnosis of HDV infection in Argentina. Finally, further research is necessary to identify high-risk populations and improve prevention and control strategies for triple and quadruple infections and their potential consequences.

A Low-Cost, Portable, Multi-Cancer Screening Device Based on a Ratio Fluorometry and Signal Correlation Technique.

The autofluorescence of erythrocyte porphyrins has emerged as a potential method for multi-cancer early detection (MCED). With this method's dependence on research-grade spectrofluorometers, significant improvements in instrumentation are necessary to translate its potential into clinical practice, as with any promising medical technology. To fill this gap, in this paper, we present an automated ratio porphyrin analyzer for cancer screening (ARPA-CS), a low-cost, portable, and automated instrument for MCED via the ratio fluorometry of porphyrins. The ARPA-CS aims to facilitate cancer screening in an inexpensive, rapid, non-invasive, and reasonably accurate manner for use in primary clinics or at point of care. To accomplish this, the ARPA-CS uses an ultraviolet-excited optical apparatus for ratio fluorometry that features two photodetectors for detection at 590 and 630 nm. Additionally, it incorporates a synchronous detector for the precision measurement of signals based on the Walsh-ordered Walsh-Hadamard transform (WHT)w and circular shift. To estimate its single-photodetector capability, we established a linear calibration curve for the ARBA-CS exceeding four orders of magnitude with a linearity of up to 0.992 and a low detection limit of 0.296 µg/mL for riboflavin. The ARPA-CS also exhibited excellent repeatability (0.21%) and stability (0.60%). Moreover, the ratio fluorometry of three serially diluted standard solutions of riboflavin yielded a ratio of 0.4, which agrees with that expected based on the known emission spectra of riboflavin. Additionally, the ratio fluorometry of the porphyrin solution yielded a ratio of 49.82, which was ascribed to the predominant concentration of protoporphyrin IX in the brown eggshells, as confirmed in several studies. This study validates this instrument for the ratio fluorometry of porphyrins as a biomarker for MCED. Nevertheless, large and well-designed clinical trials are necessary to further elaborate more on this matter.

Quantitative suppression of unsteady powerline noise in transient electromagnetic surveys: Adjustment of base-frequency and optimal choice of stacking-times.

Powerline noise is a severe interference source in urban or mine transient electromagnetic (TEM) surveys. TEM systems generally adopt the synchronous detection scheme to suppress the powerline noise. However, when the powerline frequency fluctuates differing from its nominal value (50/60Hz), the considerable powerline noise residue still remains even after synchronous detection. To overcome this problem, this paper proposes the quantitative suppression method for powerline noise taking into account the instability of powerline frequency. The method is based on the adjustment of base-frequency and optimal choice of stacking-times. We represent mathematically the sufficient condition for powerline noise suppression by synchronous detection. It consists of two equations, one with respect to base-frequency and other with respect to stacking-times. The base-frequency is adjusted according to powerline frequency estimate. We first derive the mathematical relationship between frequency estimation accuracy, residual noise amplitude, and stacking-times. Based on it, we develop an efficient algorithm to determine the optimal stacking-times. The algorithm takes as an input the powerline noise estimates and the noise tolerance limit. The tolerance limit is set to a certain value desired by the user, such as 10, 4, and 1 µV. By adjusting base-frequency and determining optimal stacking-times, the powerline noise residue after synchronous detection is reduced to below the desired tolerance limit. We verify the effectiveness of the proposed method for both simulated and actual noise. Experimental results show that the method achieves quantitative suppression of unsteady powerline noise without any damage of effective signal and prevents the measurement time loss due to excessive stacking.

Synchronous Detection of Nonlinear Phenomena in Opto-Acoustic Vibrations Induced in a Nanofilm by a Femtosecond Laser Pulse

Synchronous Detection of Nonlinear Phenomena in Opto-Acoustic Vibrations Induced in a Nanofilm by a Femtosecond Laser Pulse

Comprehensive monitoring system for high voltage cables based on the ground current signal of the cable metal sheath

Abstract This paper has presented a comprehensive monitoring system for high voltage cables based on the ground current signal of the cable metal sheath. The system can collect and process the power frequency AC current and three high-frequency partial discharge signals in real time synchronously, which realize the synchronous detection of leakage current, relative dielectric loss, harmonic, partial discharge, and improve the integration of the hardware system.