Output Signal Research Articles

Research on key circuits of high‐precision servo channel loading card for wing fatigue testing

AbstractThe key circuits of servo channel loading card with high‐precision data acquisition and output functions for wing fatigue testing are studied and improved in this paper. To solve the problem of large offset voltage in some op‐amps, non‐inverting combined amplifier circuit (NCAC) and inverting combination amplifier circuit (ICAC) are proposed by utilizing precision op‐amps combined with wide voltage and high‐power output op‐amps. In the force signal acquisition section, a non‐inverting combined zeroing filter circuit (NCZFC) is proposed to improve the precision of signal acquisition. In the excitation source output section, a non‐inverting combined excitation output circuit (NCEOC) is proposed to improve the precision of the positive excitation output; an inverting combined excitation output circuit (ICEOC) is also proposed, which improves the precision of the negative excitation output and also realizes the inversion of the input and output signals. In the servo drive output section, a non‐inverting combined voltage and current conversion circuit is proposed to improve the precision of voltage and current outputs, which has two modes of non‐inverting combined voltage output (NCVO) and non‐inverting combined current output (NCIO) modes. Simulation experiments in Multisim and actual tests have been carried out on the above improved circuits to verify the stability and precision.

SERS and electrochemical dual-mode detection of miRNA-141 by using single Au@Ag nanowire as a new platform.

As biomarkers of cancer, the accurate and sensitive detection of microRNAs is of great significance. Therefore, we proposed a surface-enhanced Raman scattering (SERS)/electrochemical (EC) dual-mode nanosensor for sensitively detecting miRNA-141. The nanosensor uses Au@Ag nanowires as a novel SERS/EC sensing platform, which has the advantages of good biocompatibility, fast response, and high sensitivity. The dual-mode nanosensor can not only effectively overcome the problem of insufficient reliability of single signal, but also realize the amplification and stable output of the detection signal, to ensure the reliability and repeatability of miRNA detection. With this sensing strategy, the target miRNA-141 can be detected over a wide linear range (100 fM to 50 nM) (LOD of 18.4 fM for SERS and 16.0 fM for electrochemical methods). In addition, the process shows good selectivity and can distinguish miRNA-141 from other interfering miRNAs. The actual analysis of human serum samples also proves that our strategy has good reliability, repeatability, and has broad application prospects in the field of analysis and detection.

Development and experimental evaluation of an acoustic flow meter prototype for measuring air flow

This study outlines the development and testing of a flow meter prototype specifically designed for use in nuclear reactor environments. The meter uses flow-induced vibration to measure flow rates and is designed for remote monitoring in harsh environments where radiation can damage electronics. The device generates a vibration signal produced by a feedback system when fluid flows out of an orifice and interacts with a downstream wedge. The frequency of the vibration signal corresponds directly to flow rate and velocity. The study investigates geometric parameters intrinsic to the prototype, such as orifice height, width, edge distance, and chamber length. Different configurations were also tested, including a bypass loop with variable cross-sections around the device. The investigation results reveal the impact of these geometric parameters on the vibration signal output, providing valuable insights for future design improvements and enhancing the effectiveness of flow metering systems used in nuclear reactor applications.

Multivalent Pt/Ti3C2Tx Nanocomposite-Based Immunochromatographic Sensor for Colorimetric/Temperature/Pressure Trimodal Detection.

Multimodal immunochromatographic sensors (ICSs) have acquired extensive attention since they not only provide reliable results by comparing the different output signals but also flexibly respond to various application environments. Herein, an ICS with triple signal outputs including colorimetry, temperature, and pressure was developed for sensitive detection of chlorothalonil. The multivalent Pt/Ti3C2Tx nanoparticles as signal tags were facilely synthesized by loading PtNPs onto single-layer Ti3C2Tx nanosheets with high surface area. The acquired Pt/Ti3C2TxNPs accelerated the rate-limiting step of the aerogenesis reaction of H2O2 for producing intensive pressure signals due to their significant catalase-mimic activity. Meanwhile, they showed desirable photothermal conversion efficiency in the near-infrared region for producing significant temperature signals. Furthermore, their deep color also allowed facile colorimetry by using the naked eye. Based on a competitive immunoassay, chlorothalonil was detected as a model analyte on this trimodal ICS platform. The detection limits for pressure, temperature, and colorimetric modes were 0.04, 0.09, and 5 ng mL-1, respectively. The recoveries for detecting chlorothalonil supplemented in Astragalus and Honeysuckle with pressure mode were 84.0-110% and 108-114%, respectively. Therefore, the ICS presented a portable, sensitive, accurate, and flexible multimodal strategy suitable for point-of-care testing.

Entropy-Driven Catalytic G-Quadruple Cycle Amplification Integrated with Ligases for Label-Free Detection of Single Nucleotide Polymorphisms.

G-Quadruplex/thioflavin (G4/THT) has become a very promising label-free fluorescent luminescent element for nucleic acid detection due to its good programmability and compatibility. However, the weak fluorescence efficiency of single-molecule G4/THT limits its potential applications. Here, we developed an entropy-driven catalytic (EDC) G4 (EDC-G4) cycle amplification technology as a universal label-free signal amplification and output system by properly programming classical EDC and G4 backbone sequences, preintegrated ligase chain reaction (LCR) for label-free sensitive detection of single nucleotide polymorphisms (SNPs). First, the positive strand LCR enabled specific transduction and preliminary signal amplification from single-base mutation information to single-strand information. Subsequently, the EDC-G4 cycle amplification reaction was activated, accompanied by the production of a large number of G4/THT luminophores to output fluorescent signals. The EDC-G4 system was proposed to address the weak fluorescence of G4/THT and obtain a label-free fluorescence signal amplification. The dual-signal amplification effect enabled the LCR-EDC-G4 detection system to accurately detect mutant target (MT) at concentrations as low as 22.39 fM and specifically identify 0.01% MT in a mixed detection pool. Moreover, the LCR-EDC-G4 system was further demonstrated for its potential application in real biological samples. Therefore, this study not only contributes ideas for the development of label-free fluorescent biosensing strategies but also provides a high-performance and practical SNP detection tool in parallel.

Development of an Anti-Discharge Unit (ADU) for gaseous proportional counters at FRIB

Sporadic harmful discharges between the detector electrodes are inherent features of the operation of proportional counters in conditions of highly ionizing background, high gas gain, or high rate. Frequent energetic discharges can deteriorate the overall performance of the detector and cause permanent damage to the detector components. In addition, they can significantly reduce the counting rate capability of the device due to the prolonged recovery time of high-voltage power supplies.In this work, we describe the development of an Anti-Discharge Unit (ADU) implemented in a Parallel-Plate Avalanche Counter (PPAC) for heavy-ion tracking. The ADU is based on a High-Voltage (HV) MOSFET switch that shuts off the electric field between the detector electrodes within a few tens of nanoseconds when the output signal is above a fixed threshold, effectively preventing the development of streamer discharges. The avalanche field is restored within a few milliseconds so that the detector dead time is small, even in the case of moderately high spark rates. The ADU can operate effectively in conditions of high rates and highly ionizing backgrounds, in addition to enhancing the detection efficiency and extending the lifetime of the electrodes.

Dual Channels Event-Triggered Asymptotic Consensus Control for Fractional-Order Nonlinear Multiagent Systems.

This article investigates the event-triggered leaderless consensus control problem for fractional-order multiagent systems (FOMASs), where both the agent-to-agent communication channel and the controller-to-actuator communication channel are based on the events. A filter is introduced to transform the original high-order system into a first-order one, greatly simplifying the complexity of controller design compared to the traditional backstepping. Further, the convergence of filtered output signals is proved to be consistent with that of the outputs of agents themselves. Superior to the traditional event-triggered scheme, two dynamic variables are designed for the triggering conditions of the communication among agents and the controller update, respectively. Via elaborately constructing the dynamic variables, zero-error leaderless consensus can be achieved instead of only ultimately uniformly bounded result. It is proved that the proposed control strategy can guarantee better control performance of leaderless consensus under limited communication resources, and Zeno behavior is excluded. Finally, two examples are provided to verify the effectiveness of our proposed control approach.

Real-Time Radiation Beam Monitoring by Flexible Perovskite Thin Film Arrays.

Real-time and in-line transversal monitoring of ionizing radiation beams is a crucial task for several applications which span from medical treatments to particle accelerators in high energy physics. Here a flexible and large area device based on 2D hybrid perovskite thin films (phenylethylammonium lead bromide), fabricated onto a thin flexible polyimide substrate, able to map the transversal beam profile of high energy radiation beams is reported. The performance of this novel tool is here compared with the one offered by standard commercial large-area technology, namely radiochromic sheets. The great potential of this class of devices is demonstrated by successfully mapping in real-time a 5 MeV proton beam at fluxes between 108 and 1010 H+ s-1 cm-2, confirming the capability to operate in a radiation-harsh environment without output signal saturation issues. The versatility and scalability of here proposed detecting system are demonstrated by the development of a multipixel array able to map in real-time a 40 kVp X-ray beam spot (dose rate 8 mGy s-1). Perovskite thin film-based detectors are thus assessed as a very promising class of thin, flexible devices for real-time, in-line, large-area, conformable, reusable, transparent, and low-cost transversal beam monitoring of different ionizing radiation.

High-precision high-stability acousto-optic pulse picking driver with a direct digital synthesis technique.

A method for maintaining a fixed phase relationship between the driving signal of acousto-optic modulator (AOM) and the original mode-locked seed laser is proposed and realized, which stabilizes the amplitude of diffracted signal output from the AOM for subsequent amplification. A field-programmable gate array (FPGA), combined with external summing amplifiers, is used to directly synthesize high-timing-precision driving signals that are synchronized with the seed laser pulses, and the accuracy of signal timing control reaches 160 ps. Using this driver, the standard deviation of the diffracted signal output from the AOM is significantly decreased from 0.52% to 0.18%. This pulse-picking solution also includes a control system that can flexibly control the frequency, gating width, etc., of the driving signal, which makes it more convenient for subsequent laser amplification and makes it suitable for a variety of mode-locked lasers.

Construction of a novel Au@Os mediated TMB-H2O2 platform with dual-signal output for rapid and accurate detection of ziram in food

The 3,3′,5,5′-tetramethylbenzidine-H2O2 (TMB-H2O2) platform has gained widespread use for rapid detection of various analytes in foods. However, the existing TMB-H2O2 platforms suffer from limited accuracy, as their signal output is confined to the visible region, which is prone to interference from various food colorants in real samples. To address this challenge, a novel Au@Os-mediated TMB-H2O2 platform is developed for both rapid and accurate detection of analytes in foods. The prepared Au@Os NPs exhibit remarkable peroxidase-like activity, making the platform display dual absorption peaks in visible and near-infrared (NIR) regions, respectively. This Au@Os-mediated TMB-H2O2 platform exhibited three linear ranges across different concentrations of ziram from 1–100, 150–600, and 800–2000 nM with limit of detection (LOD) 7.9 nM and limit of quantification (LOQ) 24.15 nM respectively. Further, the Au@Os-mediated TMB-H2O2 platform was also used for rapid and accurate detection of ziram in real food samples like apple, tomato, and black tea.

CuS hollow nanocages with rough surface to enhanced photothermal property for ultra-sensitive detection of furazolidone metabolites

Signal tracers play a key role in the lateral flow immunoassay (LFIA) for improving sensitivity and signal output capability. Photothermal signal has sparked significant excitement in designing high-performance LFIAs. Herein, CuS hollow nanocages (CuS HNCs) were synthesized for building a dual signal LFIA. CuS HNCs show excellent photothermal conversion efficiency due to their unique morphology and superior localized surface plasmon resonance (LSPR) effect. Meanwhile, the hollow-cage structure endows CuS HNCs with high light absorption and suitable colorimetric property. Furazolidone (FZD) metabolite was used as a model target in the developed LFIA to demonstrate its superior comprehensive performances brought by CuS HNCs. The limit of detection is as low as 0.099 ng mL−1 (colorimetric mode) and 0.075ng mL−1 (photothermal mode), respectively. Furthermore, standard recovery test in honey and shrimp samples was performed and the recovery rates ranged from 86.33 % to 116.71 %. This study not only introduces a new type of nanolabel characterized by an abundance of high-energy hot carriers and pronounced thermal effects, enabling the development of exceptionally sensitive immunosensor platforms but also extends applications of hollow plasmonic photothermal material in the point-of-care (POC) diagnostic field.

Detecting naphthenic acids in oil sands process water with microbial electrochemical sensor: Impact of inoculum sources and quorum sensing autoinducer

This study presents the inaugural demonstration of a microbial electrochemical cell (MXC)-based biosensor for naphthenic acids (NAs) detection in oil sands process water (OSPW) from a mining site. During the calibration process, different operating parameters were evaluated, including standing times (3 – 12 hours) and charging durations (5 – 20 minutes) within the charging-discharging cycles. The observations ascertained that a combination of a 12-hour standing period followed by a 15-minute charging period yielded the optimal current output when measuring NA concentrations ranging from 4.98 to 24.9 mg/L in real OSPW samples (diluted to concentrations of 20–100 %). Subsequently, incorporating diverse inoculum sources from MXCs led to significant signal output improvements, with one sustained on a mixture of cyclohexane carboxylic acids, commercial naphthenic acids, and real OSPW, and another exposed to acetate medium for over four years. Moreover, integrating quorum sensing (QS) autoinducers (10 μM) increased the current generation, highlighting the potential for more sensitive detection capabilities. Ultimately, our MXC biosensor could enable a cost-effective and rapid detection of OSPW NAs, offering a potential alternative for environmental surveillance.

Flexible ZIF-67@PVDF tree-like nanofiber membrane with high piezoelectric output for energy harvesting

Modern demands for efficient, environmentally friendly, and self-powered devices have led to growing interest in piezoelectric polymers in the scientific community. In this paper, a ZIF-67 functionalized polyvinylidene fluoride/ tetrabutylammonium hexafluorophosphate tree-like nanofiber membrane (ZIF-67@PVDF/TBAHP-TLNMs) was developed as piezoelectric nanogenerator for energy harvesting. The ZIF-67@PVDF/TBAHP-TLNMs was prepared by in-situ growth of ZIF-67 on the surface of PVDF TLNMs, which demonstrated remarkable energy harvesting capabilities. The results indicated that the β-phase content of the in-situ growth of ZIF-67 reached 86.94 %, augmented the fiber's rotation radius, and elevated the electromechanical conversion efficiency. Notably, the short circuit current reached 3.87 μA and the output voltage exceeded 9.78 V, which was 10.7 times and 5.9 times higher than the electrical signal output of pure PVDF nanofiber membrane, respectively. Furthermore, the ZIF-67@PVDF/TBAHP-TLNMs exhibited exceptional mechanical properties, with an elastic modulus as high as 1.13 GPa, outperforming other nanofiber membranes and catering to the diverse requirements of wearable devices. During a 500 s test cycle, its layered structure remained intact, without any discernible damage or interlayer separation of the nanofibers. At the same time, the device exhibited high electromechanical conversion efficiency and a sensitive sensing function, which made it have broad application prospects in human motion monitoring and intelligent wearable devices.

Temperature-based energy changes in gold nanowire sensors for flow rate detection and failure prediction

This study delves into the dynamic operational states of nanowire sensors within microfluidic channels for flow velocity detection, classifying these states into decline, steady, and failure states. It conducts a comparative analysis of the steady-state operational characteristics of nanowire sensors across various voltages and inlet flow rates, alongside examining the interplay between nanowire resistivity and temperature. This investigation identifies an optimal working condition for the sensor at a 1 V operating voltage and a nanowire dimension of 150 × 150 nm. Employing both theoretical and experimental approaches, the research elucidates the convective heat transfer mechanism that underpins the functionality of the nanowire sensor for flow rate detection. It unveils the pattern of nanowire temperature changes during inlet flow rate measurement within a range from 10 to 50 μL/min range and establishes standard values of temperature and calorimetric differences for various flow velocities. Furthermore, the study achieves the prediction of the time to reach the steady and failure states under given operational conditions for the nanowire-based sensor. This advancement will enhance the reading precision of the signal output from the nanowire sensor, mitigate the risk of sensor failure, and contribute to prolonging the operational lifespan of equipment.

Event-triggered secure control for Markov jump neural networks with time-varying delays and subject to cyber-attacks via state estimation fuzzy approach

The investigation uses a state estimation fuzzy technique to address the problem of dynamic event-triggered secure control in Markov jump neural networks with time-varying delays subject to cyber-attacks. Two different deception attacks are given, each employing stochastic variables with a Bernoulli distribution. Specifically, this article presents a dynamic event-triggered strategy and energy restrictions to reduce network traffic and protect network resources during deception attacks. To prevent the system state from becoming unavailable, a state estimator is concurrently developed using the output signal. The application of Lyapunov stability theory yields sufficient criteria that ensure neural network stability. The study also accurately describes the controller gain's by solving Linear matrix inequality. Numerical examples are provided to demonstrate the theoretical results.

A ratiometric nanoplatform for fluorimetric and visual detection of Cu2+ and biothiols based on Eu MOFs and carbon dots

Herein, a ratiometric nanoplatform was established for fluorimetric and visual detection of Cu2+ and biothiols based on europium-based metal–organic frameworks (Eu MOFs) and carbon dots (CDs). Fluorescent Eu MOFs with red emission was facilely prepared via the coordination of Eu3+ with tetracycline (TC) and 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid (Hepes). However, with addition of Cu2+, the fluorescence of Eu MOFs significantly decreased due to higher affinity of Cu2+ with TC, whereas the green fluorescence of CDs was not influenced by Cu2+, which served as an internal standard of the sensing platform. Interestingly, after introducing biothiols, the stronger coordination between Cu2+ and the sulfydryl of biothiols induced the release of TC to coordinate with Eu3+, thus recovering the fluorescence of Eu MOFs. The ratio changes of these two emissions accompanying by the distinct color variations of the solution under a 365 nm ultraviolet lamp could be used as output signals for fluorimetric and visual detection of Cu2+ and biothiols. The nanoplatform exhibited excellent sensing performance with limit detection as low as 0.57 μM for Cu2+, 0.54 μM for glutathione, 0.14 μM for homocyeteine and 0.42 µM for cysteine, respectively. In addition, it was successfully applied to detecting Cu2+ in environment water samples and biothiols in human serum samples, suggesting great potential for Cu2+ and biothiols determination in environmental and biological samples.

A self-powered sensor based on hollow bimetallic sulfide and double-strand TSDR amplification achieves sensitive miRNA-21 detection

MicroRNA (miRNA) sensitive detection is significant for cancer diagnosis. Currently, self-powered biosensors in clinical miRNA detection show the advantages of no external power supply, mild reaction conditions, low cost and portability. In this work, the bimetallic sulfide heterojunction hollow nanocubes are prepared as the substrate material, which can significantly improve the electrochemical reaction rate and increase the enzyme load. Meanwhile, we design the independent duplex-chain assisted toehold mediated strand displacement reaction (TSDR) strategy. The two substable double chains trigger a continuous chain displacement reaction, and the current signal amplification is realized based on molecular recognition. The constructed sensor has a linear response range of 0.05–10000 fM and a detection limit (LOD) of 8.3 aM. In addition, we use commercial apps to present signals, fundamentally changing the signal output mode of electrochemical sensors, and facilitating the construction of a portable real-time sensor platform. The self-powered biosensor has the characteristics of good biocompatibility, real-time monitoring and economic efficiency in miRNA detection, which provides a new idea for sensitive detection of miRNA. Moreover, it has far-reaching reference significance for the development of other sensing technologies, which is expected to extend from the medical field to environmental monitoring, food safety and other fields.

Neural network-based distributed consensus tracking control for uncertain Euler–Lagrange systems over directed topologies

This paper proposes a neural network-based robust control approach for driving disturbed Euler–Lagrange systems (e.g., robot manipulator) in a directed network to perform consensus tracking of a heterogeneous leader’s output signal. The parameter matrices and external disturbances in each follower’s Euler–Lagrange dynamics are unmeasurable, thus we unify them into one lumped uncertainty term. Neural networks are then employed to online estimate these uncertainties, with adaptive update laws ensuring the boundedness of the estimation errors. Subsequently, a set of distributed observers are developed to adaptively estimate the leader’s states as well as the unidentified parameter vector and output matrix in the leader’s model. With their help, the robust cooperative controller is designed. Its efficacy on directed networks is theoretically justified by designing a Lyapunov function with a special structure. This function produces symmetric positive definite matrices when its first derivative terms interact with the specified parameters in the observer and Laplacian matrices for directed graphs. Finally, numerical simulations based on two-link robot manipulators are carried out to verify that the tracking errors converge to zero when applying the neural network-based robust controller.

Rancang Bangun Green Portable Cooler Box

Freon is one of the refrigerants used in refrigeration systems. The refrigeration system has a very important role, namely to preserve food ingredients so that food can last longer. The use of freon is not only used in ships but is widely found in home appliances in refrigeration systems used in freezers, air conditioners, refrigerators, and dispensers. If more freon is used, the negative impact that arises is greater, namely the depletion of the ozone layer and global warming which can have a bad influence on health, the life of living things and the environment. The purpose of this researcher is to create a tool to reduce the negative impact of freon use, namely by using peltier as a cooling medium with environmentally friendly thermoelectric modules. This study uses trial and error methods. Where the trial process is carried out by turning on one of the working push buttons and observing the temperature value. Then it is processed by the control system, namely Arduino Mega which will later provide a PWM output signal to the IRF540 mosfet when the output temperature value is in line with the reference value and vice versa. The test of this tool was carried out by comparing measurements between the author's prototype tool and the standard measuring tool, namely the digital thermometer. Based on the test results, this device can produce a minimum temperature of 140C at 30-minute intervals without any media. The trial using 330ml bottled water can reach a temperature of 170C within 30 minutes in the cooler box. This tool is also equipped with an automatic monitoring system using a PWM signal in the form of a change in fan speed, which is 255 RPS maximum speed and when getting a PWM signal it changes to 50 RPS. The percentage of errors resulting from the comparison of standard measuring instruments and sensor values had the highest and lowest percentages of 2.37% and 0.84% in cold dispersion conditions without charge. Then the highest and lowest error percentages were 1.69% and 0.72% in the state of containing a load of 1 330ml mineral bottle. This ptototype uses data recording using Micro-SD as a data logger.

A single-microbe living bioelectronic sensor for intracellular amperometric analysis

Subcellularly amperometric analysis in situ is crucial for understanding intracellular redox biochemistry and subcellular heterogeneity. Unfortunately, the ultra-small size and complex microenvironment inside the cell pose a great challenge to achieve this goal. To address the challenge, a minimized living microbial sensor has been fabricated in this work for amperometric analysis. Here, by fabricating the dimidiate microelectrode as the working electrode, while fitting a living electroactive bacterium (EAB) as the transducer, outward extracellular electron transfer (EET) of the sensory EAB is correlated with the concentration of lactic acid, which is electrochemically recorded and thus displays an electrical signal output for detection. In specific, the S. oneidensis modified dimidiate microelectrode (S.O.@GNE-NPE) acts as an integrated electroanalytical device to generate the electrical signal in situ. The established microcircuit provides unprecedented precision and sensitivity, contributing to subcellular amperometric measurement. The microbial sensor shows a linear response in the concentration range of 0–60 mM, with a limit of detection (LOD) at 0.3 mM. The microsensor also demonstrates good selectivity against interferences. Additionally, intracellular analysis of lactic acid provides direct evidence of enhanced lactic metabolism in cancer cells as a result of “Warburg Effect”. This work shows an example of nano-, bio- and electric technologies that have been integrated on the EAB-modified dimidiate microelectrode, and achieves intracellular biosensing application through such integration. It may give a new strategy on the combination of micro/nanotechnologies with sensory EAB for the necessary development of bioelectronic devices.