Detection Circuit Research Articles

Design and implementation of a full analogue gate driver for current compensation of paralleled SiC‐MOSFETs

AbstractSilicon carbide MOSFETs have current ratings that are not sufficiently high to be used in high‐power converters. It is necessary to connect several MOSFETs in parallel in order to increase current capabilities. However, transient imbalance peak currents during turn‐on and ‐off processes challenge the performance and reliability of parallel MOSFETs. This paper considers the impact factors of device parameters, asymmetrical power circuit layout and circuit parasitic analytically to reveal the imbalance current peaks. The turn‐on and ‐off transient conditions are studied and mathematically investigated. In master‐slave configuration, a fully analogue active gate driver is designed and implemented to suppress the imbalance current among parallel silicon carbide (SiC) MOSFETs. In the proposed scheme, by exploiting an imbalance current detection circuit and I‐controller in a negative feedback for the slave MOSFET, an appropriate control voltage is obtained. The output voltage of active gate driver is adjusted by the control voltage, whether positive or negative in turn‐on and ‐off transient, in order to synchronize the peak currents of paralleled modules. Moreover, a detailed circuit of the designed compensator is presented and discussed. The experimental results are presented to verify the reliability and the effectiveness of the proposed compensator.

Employing the pyroelectric effect in LiTaO3 thin film for infrared detection of complex gases

Abstract In this paper, the lithium tantalite ( LiTaO 3 ) thin film has been employed as the highly sensitive element for infrared detection of compound (refrigerant) gases such as 1,1,1,2-Tetrafluoroethane ( C 2 H 2 F 4 ) and 1,1,1,2,3,3,3-Heptafluoropropane ( C 3 F 7 H ). The LiTaO 3 thin film was subjected to the mid-infrared light from output transmission spectra of C 2 H 2 F 4 as well as C 3 F 7 H molecules used as sources. The technology for preparation of LiTaO 3 thin film as well as detector design and manufacturing are presented. Particular attention was paid to production of conductive electrodes, including a very thin semitransparent Au layer evaporated on the top surface of LiTaO 3 pyroelectric material. Important characteristics of the LiTaO 3 based pyroelectric system are briefly discussed. Additionally, the design, construction, and performance of the gas chamber operating as a channel for gas sensor testing is briefly described. The pyroelectric open-circuit voltage generated in LiTaO 3 was boosted with a signal processing circuit for selective high-sensitivity detection of compound gases at room temperature. The infrared (IR) filters such as titanium dioxide ( TiO 2 ) and zinc oxide ZnO having narrow bandwidth and working at a normal incidence were integrated into a compact and portable pyroelectric micro-sensor before the LiTaO 3 pyroelectric element in the same package for cleaning background in a broad IR spectrum of both refrigerant gases. The performance, stability, and accuracy of fabricated LiTaO 3 -based IR gas sensors operating on the pyroelectric open-circuit voltage were tested and improved. IR gas sensors designed and prepared in this study can be utilized for non-contact, sensitive, and selective detection of highly hazardous and explosive gases.

A novel chitosan/quercetin-based film enables non-enzymatic detection of glucose: Electrochemical and fluorescent behavior

In this study, a novel functional hydrogel film was synthesized using natural polymer chitosan and quercetin as raw materials. Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) analysis indicate that phenylboronic acid modified carbon nanodots (PBA-CDs) were successfully prepared via a simple microwave-assisted hydrothermal method. The experimental results demonstrate that a dual electrochemical and fluorescence detection of glucose can be realized based on the boronate ester bonding between chitosan/quercetin (Chit0/Quer) films and PBA-CDs. The addition of PBA-CDs hinders the electron transfer between the phenolic hydroxyl groups of quercetin and the redox mediators, and inhibits the intramolecular rotation of quercetin, which leads to a decreased electrical signal and enhanced fluorescence intensity. After the addition of glucose, the peak redox current of the Chit0/Quer hydrogel film is restored due to the competitive binding of glucose to the boronate ester, resulting in a dual-input logic circuit for the qualitative detection of glucose. In addition, the fluorescence intensity of the hydrogel decreases with increasing glucose concentration, and the concentration of glucose can be quantitatively detected by detecting the change in fluorescence intensity. Besides, the sensor has better stability and selectivity for biomarkers. Finally, we demonstrate that the electrochemical and fluorescence sensing strategies can be used for the detection of glucose in real beverage samples. In conclusion, based on the redox activity of quercetin and the competitive binding of boronate ester bonds, we explored a new strategy for enzyme-free electrochemical and fluorescence sensing for the detection of glucose, which is expected to be applied in biomedicine, food industry and other fields.

An energy-efficient circuit for online detection of R- and P-waves from ECG signals in analog domain

An energy-efficient circuit for online detection of R- and P-waves from ECG signals in analog domain

Reference-Attached pH Nanosensor for Accurately Monitoring the Rapid Kinetics of Intracellular H+ Oscillations.

Intracellular pH (pHi) is an essential indicator of cellular metabolic activity, as its transient or small shift can significantly impact cellular homeostasis and reflect the cellular events. Real-time and precise tracking of these rapid pH changes within a single living cell is therefore important. However, achieving high dynamic response performance (subsecond) pH detection inside a living cell with high accuracy remains a challenge. Here a reference-attached pH nanosensor (R-pH-nanosensor) with fast and precise pHi sensing performance is introduced. The nanosensor comprises a highly conductive H+-sensitive IrRuOx nanowire (SiC@IrRuOx NW) as the intracellular working electrode and a SiC@Ag/AgCl NW as an intracellular reference electrode (RE) to diminish the interferences arising from cell membrane potential fluctuations. This whole-inside-cell detection mode ensures that the entire potential detection circuit is located within the same cell, and the R-pH-nanosensor is able to quantify the mild acidification of cytosol and completely record the fast pH variation within a single cell. It also enables real-time potentiometric monitoring of the pHi oscillations, which synchronize with the glycolysis oscillations in cancer cells. Furthermore, the asymmetry in glycolysis oscillations wave is disclosed and the inhibitory effect of just lactate to glycolysis oscillations is further confirmed.

A wide-frequency triboelectric vibration sensor for self-powered machinery health monitoring

Abnormal vibration is usually a precursor to structural damage and performance degradation industrial equipment and transportation. Vibration detection at critical locations such as electrical motors and bearings within large equipment has emerged as an indispensable method for machinery health monitoring. Current vibration detection instruments mostly need to be powered by cables or batteries, which has application limitations in complex moving equipment and restricted space. In this paper, a disc-like triboelectric nanogenerator (DL-TENG) with a multi-sized honeycomb structure is proposed as an innovative solution for achieving wide band and high precision acceleration detection of the vibration. Multi-diameter polytetrafluoroethylene (PTFE) balls are used as friction materials to achieve the high voltage output of the TENG, providing sufficient energy for the detection circuit. By carefully designing suitable honeycomb structures for PTFE balls of different diameters, the ability to detect broadband vibration signals is obtained. The experimental results demonstrate that DL-TENG with honeycomb structure and multi-size PTFE balls can detect acceleration signals ranging from 10 to 2000 Hz, and the acceleration measurement range can reach 1–11 m/s2 with an acceleration resolution of 0.1 m/s2. Moreover, DL-TENG can output more than 80 V peak-to-peak under vibration conditions of 11 m/s2. And under vibration conditions of 8 m/s2, the DL-TENG can fully charge a 100 μF capacitor to 5 V in just 100 seconds. By equipping a special circuit for DL-TENG, wireless self-powered vibration detection is realized. This study is expected to be applied in the scenario of vibration information collection in complex ring vibration environment and provides a new paradigm for the realization of self-powered vibration sensors.

Acoustofluidic Tweezers Integrated with Droplet Sensing Enable Multifunctional Closed-Loop Droplet Manipulation.

Droplet manipulation technologies with surface acoustic waves attract significant attention for applications in fluid handling and bioanalysis. However, existing technologies face challenges in automation, precision, and functional integration, limiting broader applications. In this work, a highly integrated droplet-sensing acoustofluidic tweezer is developed, incorporating orthogonally arranged slanted finger interdigital transducers and a custom-designed control and detection circuit system. Using a single acoustic device, this tweezer enables switchable acoustic droplet manipulation and detection, providing multifunctional closed-loop manipulation of on-chip microliter-scale droplets. The platform takes advantage of the wideband frequency response characteristics of the transducers, along with an automated droplet detection algorithm, enabling high-precision detection of central positions, edge positions, contact diameters, and the number of droplets. With this feedback, automated closed-loop control of various droplet manipulation functions, including transportation, merging, mixing, splitting, and internal particle enrichment, is achieved for the first time on a single acoustic platform. This significantly enhances the precision, efficiency, and fault tolerance of the manipulation process. This droplet-sensing acoustofluidic tweezer provides an innovative acoustic solution for droplet manipulation technologies in fields such as fluid processing and biosensing, demonstrating significant application potential.

Review on peak detect and hold circuits and their applicability in partial discharge detection

Abstract This article reviews various designs of electrical peak detect and hold circuits and tests their applicability for the detection of partial discharge pulses. Since partial discharges are very short pulses in the nanosecond range, the peak detector circuit must be very fast and thus work precisely over a wide bandwidth up to the GHz range. The article begins with a comprehensive literature review and gives an overview of the state of the art of peak detector circuits. As a result of the literature research, four different peak detector designs are identified that appear suitable for measuring partial discharges. These four circuits are then simulatively tested for their performance in measuring the pulse height of various partial discharge pulses. It turns out that two of the identified circuits are able to measure nanosecond pulses of small amplitude. These two circuits must be further optimized for partial discharge detection in the future. In addition, the circuit should be tested prototypically with real partial discharge pulses.

A novel method reflecting mechanical-electrical conversion process of triboelectric nanogenerators and its application in human-machine interaction

Triboelectric nanogenerators (TENGs) provide interpretable electrical signals to characterize mechanical motion processes during energy conversion, making them suitable sensors for applications in human-machine interaction, human motion characterization, and health monitoring. Nevertheless, the accurate characterization of the mechanical-electrical conversion process and improvement of sensor reliability necessitates the establishment of highly precise quantitative relationships between electrical signals and movement of TENGs. In this study, we propose a method for the accurate analysis of the continuous movement state of TENG, which allows for the successful reflection the mechanical-electrical conversion process of three types of TENG based on a unique charge detection circuit. The charge detection circuit, constructed from low-cost electronic components, is able to convert the weak charge signal from the TENG into a modest voltage signal, allowing seamless integration into a conventional electronic system. Subsequently, based on the method, we demonstrate the detection of charge output at the millimeter scale of TENG movement as well as the control of a manipulator by the electrical charge output generated by the finger. In addition, a portable multi-channel signal acquisition system was designed to enable the characterization of diversified gestures. This work not only provides an inexpensive and reliable solution for TENG-based sensing applications in the extraction of movement information but also promotes the engineering applications of triboelectric sensors to some extent.

Light tunes a novel long-term threat avoidance behavior.

Animals must constantly scan their environment for imminent threats to their safety. However, they must also integrate their past experiences across long timescales to assess the potential recurrence of new threats. Though visual inputs are critical for the detection of environmental danger, whether and how visual information shapes an animal's assessment of whether a new threat is likely to reappear in a given context is unknown. Using a novel behavioral assessment of long-term threat avoidance behavior, we find that animals will avoid a familiar location where they previously experienced a single exposure to an innately threatening visual stimulus. This avoidance behavior is highly sensitive and lasts for multiple days. Intriguingly, we find that the melanopsin-expressing, intrinsically photosensitive retinal ganglion cells tune this behavior via a perihabenular-nucleus accumbens circuit distinct from the canonical visual threat detection circuits. These findings define a specific retinal cell type driving a new long-term threat avoidance behavior driven by prior visual experience.

Repeated presentation of visual threats drives innate fear habituation and is modulated by environmental and physiological factors.

To survive predation, animals must be able to detect and appropriately respond to predator threats in their environment. Such defensive behaviors are thought to utilize hard-wired neural circuits for threat detection, sensorimotor integration, and execution of ethologically relevant behaviors. Despite being hard-wired, defensive behaviors (i.e. fear responses) are not fixed, but rather show remarkable flexibility, suggesting that extrinsic factors such as threat history, environmental contexts, and physiological state may alter innate defensive behavioral responses. The goal of the present study was to examine how extrinsic and intrinsic factors influence innate defensive behaviors in response to visual threats. In the absence of a protective shelter, our results indicate that mice showed robust freezing behavior following both looming (proximal) and sweeping (distal) threats, with increased behavioral vigor in response to looming stimuli, which represent a higher threat imminence. Repeated presentation of looming or sweeping stimuli at short inter-trial intervals resulted in robust habituation of freezing, which was accelerated at longer inter-trial intervals, regardless of contextual cues. Finally, physiological factors such as acute stress further disrupted innate freezing habituation, resulting in a delayed habituation phenotype, consistent with a heightened fear state. Together, our results indicate that extrinsic factors such as threat history, environmental familiarity, and physiological stressors have robust and diverse effects on defensive behaviors, highlighting the behavioral flexibility in how mice respond to predator threats.

Research on underwater acoustic detection technology based on optical waveguide resonator cavity

PurposeIn acoustic detection technology, optical microcavities offer higher detection bandwidth and sensitivity than traditional acoustic sensors. However, research on acoustic detection technologies involving optical microcavities has not yet been reported. Therefore, this paper aims to design and construct an underwater acoustic detection system based on optical microcavities and study its acoustic detection technology to improve its performance.Design/methodology/approachBased on the principles of optical microcavity acoustic sensors, a signal-detection circuit was designed to form a detection system in conjunction with a laser, an optical waveguide resonator and an oscilloscope. This circuit consists of two modules: a photodetection module and a filter amplification module.FindingsThe photodetection module features a baseline noise of −106.499 dBm and can detect device spectral line depths of up to 2410 mV. The gain stability of the filter amplification module was 58 dB ± 1 dB with a noise gain of −107.626 dBm. This design allows the acoustic detection system to detect signals with high sensitivity within the 10 Hz−1.2 MHz frequency band, achieving a maximum sensitivity of −126 dB re 1 V/µPa at 800 Hz and a minimum detectable pressure (MDP) of 0.37 mPa/Hz1/2, corresponding to a noise equivalent pressure (NEP) of 51.36 dB re 1 V/µPa.Originality/valueThis study designs and constructs a broadband underwater acoustic detection system specifically for optical waveguide resonators based on the sensing principles of silicon dioxide optical waveguide resonators. Experiments demonstrated that the signal detection module improves the sensitivity of underwater acoustic detection based on optical waveguides.

Modeling and experimental characterization of a compact Mach–Zehnder electro-optic modulator on the SOI

The Mach–Zehnder electro-optic modulator (MZM) plays a crucial role in photonics integration technology during signal transmission. We propose the design and fabrication of a silicon-based electro-optic modulator based on the M-Z structure and design a modulator using silicon as the waveguide core layer on a silicon dioxide substrate. The detailed design involves a 1×2 splitter, branch waveguides, modulating arm waveguides, and a 2×1 combiner. The MZM fabrication and characterization results reveal that the half-wave voltage of the silicon-based MZM is 2 V, with an optical loss of −2.464dB and a device core size of 450µm×2800µm. The experimental results indicate that the MZM with a low half-wave voltage, a low loss, and high integration has significant value. The proposed MZM exhibits considerable improvements, featuring a low half-wave voltage and a low loss, and this device may serve as a fundamental component in wearable large-scale photonic integrated circuits for weak ECG real-time detection.

A ring resonators optical sensor for multiple biomarkers detection

In the recent years, the number of Point-Of-Care-Tests (POCTs) available for clinical diagnostic has steadily increased. POCTs provide a near-patient testing with the potential to generate a result quickly so that appropriate treatment can be implemented, leading to improved clinical outcomes compared to traditional laboratory testing. Technological advances, such as miniaturization of sensors and improved instrumentation, have revolutionized POCTs, enabling the development of smaller and more accurate devices. In this context, it has also gained increasing importance the screening of various analytes simultaneously to increase specificity and improve the characterization of the disease. This study is aimed at developing and characterizing a photonic integrated circuit for multiple markers detection, which represents the functional core towards a full developed POCT device for clinical pathology applications. The photonic sensor, based on microring resonators (MRRs), is functionalized by immobilizing specific antibodies on a copolymer layer deposited on the MRR’s surfaces. Surface chemical techniques were employed to analyse the surface chemical characteristics while fluorescence microscopy was involved to analyse the resulting bioreceptor surface density. The photonic sensor is characterized for the parallel detection of two biomarkers, the C-Reactive Protein (CRP) and the Creatine-Kinase-MB (CK-MB). The analyte-antibody binding curves were obtained both in buffer and in filtered un-diluted artificial saliva showing promising results both in terms of sensitivity, with limit of detection (LOD) of 103 pM for CRP and 140 pM for CK-MB, and in terms of specificity. These encouraging results let the assembly of a highly sensitive POC device for molecular diagnostics.

Antagonistic action of Siah2 and Pard3/JamC to promote germinal zone exit of differentiated cerebellar granule neurons by modulating Ntn1 signaling via Dcc.

Exiting a germinal zone (GZ) initiates a cascade of events that promote neuronal maturation and circuit assembly. Developing neurons and their progenitors must interpret various niche signals-such as morphogens, guidance molecules, extracellular matrix components, and adhesive cues-to navigate this region. How differentiating neurons integrate and adapt to multiple cell-extrinsic niche cues with their cell-intrinsic machinery in exiting a GZ is unknown. We establish cooperation between cell polarity-regulated adhesion and Netrin-1 (Ntn-1) signaling comprises a coincidence detection circuit repelling maturing neurons from their GZ. In this circuit, the Partitioning defective 3 (Pard3) polarity protein and Junctional adhesion molecule-C (JamC) adhesion protein promote, while the Seven in absentia 2 (Siah2) ubiquitin ligase inhibits, Deleted in colorectal cancer (Dcc) receptor surface recruitment to gate differentiation linked repulsion to GZ Ntn-1. These results demonstrate cell polarity as a central integrator of adhesive- and guidance cues cooperating to spur GZ exit.

Design of non‐contact capacitive displacement detection methods for magnetic levitated sphere

AbstractTo meet the demand for non‐contact displacement detection of magnetic levitation spheres, single‐ended and differential variable electrode distance capacitance displacement detection schemes are designed in this paper. For these two schemes, finite element simulation models are established in COMSOL Multiphysics software to obtain the relationship between the test capacitance and the displacement of the magnetic levitation sphere. In the single‐ended scheme, there is a non‐linear relationship between the test capacitance and the position of the levitated sphere, and this non‐linearity becomes more significant as the sphere moves away from the electrode plate. In contrast, in the differential scheme, the test capacitance and the displacement of the levitated sphere follow a linear relationship, but the test sensitivity decreases with the expansion of the measuring range. The simulation results of the differential scheme have been verified by building a spherical displacement detection simulator, and thanks to the mature development of capacitive detection circuits, the scheme is expected to achieve better than nanoscale displacement detection resolution in the 6.6 mm displacement range of a magnetic levitation sphere in the future.

Solid-Phase microextraction on Self-Driven microfluidic chip using capillary micropump and microvalves for saliva electrochemical analysis

The real-time detection of biomarkers in saliva is of great significance for early non-invasive diagnostic of related diseases. In this work, molecular imprinting technology was used to prepare a lactic acid monolithic column, which could realize specific adsorption and elution of lactic acid, achieving solid phase microextraction (SPME) of lactic acid in samples, and purify the analytes. Lactic acid monolithic column was then embedded into the microfluidic channel, and passive microfluidic structures such as stop valve, retention valve, trigger valve and capillary pump were utilized to construct the SPME self-driven microfluidic chip. A series of complex operations such as lactic acid adsorption, rinse and elution on the monolithic column could be realized automatically without external power. Since the purification of the analytes was achieved by the monolithic column, the low-cost nano copper oxide modified electrode was used to achieve the specific electrochemical analysis of lactic acid. The screen-printed electrode was designed and fabricated, and the integrated electrochemical detection circuit was used to realize the portable analysis of Na+, K+ and lactic acid simultaneously. The microfluidic chip, screen-printed electrode and miniaturized detection circuit are integrated into a Point-of-care testing (POCT) device, which realizes the automatically real-time detection of saliva. By adjusting the template molecule in monolithic column polymerization, the application of this physiological fluid POCT device can be extended, and may provide some implications for the development of portable non-invasive health monitoring devices.

Predictive control method with conduction mode detection to suppress input current distortion of three‐level power factor correction

AbstractA novel predictive control method with conduction mode detection is proposed to suppress input current distortion of three‐level power factor correction (PFC) converters. In PFC converter, the input current is mostly distorted in continuous conduction mode (CCM) with conventional control methods. The proposed predictive control method comprises of a predictive CCM algorithm, a predictive discontinuous conduction mode (DCM) algorithm, and a conduction mode detection technique. By analysing four switching states of PFC converter and based on the inductor current ripple, predictive control duty cycles in CCM and DCM are derived, and the optimal duty cycle is determined by forecasting the next cycle current. According to the duty cycle characteristics, the conduction mode is detected without additional detection algorithms and circuits, achieving the input current tracking the input voltage. Finally, the effectiveness and correctness of the proposed predictive control method are validated through simulation and experiment.

Design and Performance Evaluation of an In Situ Online Soil Electrical Conductivity Sensor Prototype Based on the High-Performance Integrated Chip AD5941

Soil electrical conductivity has an important influence on the growth and development of plants. The existing real-time soil electrical conductivity detection device is affected by temperature, inconvenient to use, expensive, etc.; therefore, based on the classical four-terminal method of soil electrical conductivity detection principle, in this study, we aim to improve the limitations of the constant current source, selecting the high-performance integrated chip AD5941, optimizing the detection circuit and probe structure, improving the achievability of the detection circuit, and designing a type of in situ on-line real-time access to a soil electrical conductivity detection device, and improve the detection accuracy by temperature compensation. In this paper, dynamic performance, steady state performance, radial sensitivity range, and calibration test are carried out for the soil electrical conductivity detection prototype. The test results show that the dynamic response speed of the prototype is less than 50 ms, the steady state error is not more than ±2%, and the radial measurement sensitivity range is 8~10 cm. A comparison with the commercial sensor shows that the linear fit of the two measurements reaches 0.9995, and the absolute error ranges from −61.40 µS/cm to 23.90 µS/cm, with a relative error range of −1.94~1.86%. It shows that the performance of the two sensors is comparable, but the quality/price ratio of the prototype is much higher than that of the commercialized product. In this study, it is demonstrated that a high-precision, low-cost, and easy-to-use in situ online soil electrical conductivity detection device can be provided for agricultural and forestry production.

Pixel Circuit Design for X-ray Detection Utilizing a-IGZO Thin-Film Transistors

Abstract In recent advancements, X-ray detectors have made significant progress. Active pixel sensors exhibit superior Signal-to-Noise Ratio (SNR) compared to passive counterparts. The conventional pixel circuit for X-ray detectors has three transistors and one capacitor. We focused on simplifying this pixel to enhance resolution. Our research introduces and verifies a novel pixel circuit developed for high-resolution X-ray detectors. The proposed pixel circuit is composed by two n-type thin-film transistors and one capacitor. It requires two scan pulses and three operational stages. This structure can effectively reduce the component area of the pixel circuit. We designed RPI LEVEL = 35 amorphous TFT model and simulated for verify our proposed pixel circuit. In results, proposed pixel circuit successfully operated and shows 2.5 μV when the equivalent resistance of detector (RDetector) is 10 MΩ, and 8.38 V when RDetector is 1 MΩ. To minimize the harmful effects of X-ray exposure, reducing the dosage is essential. Sensitivity and low noise are crucial factors, and the proposed circuit offers a compact design, increased sensitivity, and higher output voltage.