Search

The rising demand for increased integration and higher power outputs poses a hidden risk to the long-term reliable operation of third-generation semiconductors. Thus, the power cycling test (PCT) is widely regarded as the utmost critical test for assessing the packaging reliability of power devices. In this work, low-thermal-resistance packaging design structures of SiC devices are introduced, encompassing planar packaging with dual heat dissipation, press-pack packaging, three-dimensional (3D) packaging, and hybrid packaging. PCT methods and their control strategies are summarized and discussed. Direct-current PCT is the focus of this review. The failure mechanisms of SiC devices under PCT are pointed out. The electrical and temperature-sensitive parameters adopted to monitor the aging of SiC devices are organized. The existing international standards for PCT are evaluated. Due to the lack of authoritative statements for SiC devices, it is difficult to achieve comparison research results without consistent preconditions. Furthermore, the lifetimes of the various packaging designs of the tested SiC devices under PCTs are statistically analyzed. Additionally, problems related to parameter monitoring and test equipment are also summarized. This review explores the broader landscape by delving into the current challenges and main trends in PCTs for SiC devices.

In this study, the bipolar switching behaviors in ZnO/HfO2 bilayer resistive random-access memory (RRAM), depending on different metal top electrodes (TE), are analyzed. For this purpose, devices with two types of TE–TiN/Ti and Pd, which have varying oxygen affinities, are fabricated. X-ray diffraction (XRD) analysis shows that ZnO has a hexagonal wurtzite structure, and HfO2 exhibits both monoclinic and orthorhombic phases. The average grain sizes are 10.9 nm for ZnO and 1.55 nm for HfO2. In regards to the electrical characteristics, the I–V curve, cycling test, and voltage stress are measured. The measurement results indicate that devices with TiN/Ti TE exhibit lower set and higher reset voltage and stable bipolar switching behavior. However, a device with Pd TE demonstrates higher set and lower reset voltage. This phenomenon can be explained by the Gibbs free energy of formation (∆Gf°). Additionally, the Pd TE device shows unstable bipolar switching characteristics, where unipolar switching occurs simultaneously during the cycling test. This instability in devices with Pd TE could potentially lead to soft errors in operation. For guaranteeing stable bipolar switching, the oxygen affinity of material for TE should be considered in regards to ZnO/HfO2 bilayer RRAM.

All-inorganic perovskite semiconductors have received significant interest for their potential stability over heat and humidity. However, the typical CsPbI3 displays phase instability despite its desirable bandgap of ~1.73 eV. Herein, we studied the mixed halide perovskite CsPbI2Br by varying the silver doping concentration. For this purpose, we examined its bandgap tunability as a function of the silver doping by using density functional theory. Then, we studied the effect of silver on the structural and optical properties of CsPbI2Br. Resultantly, we found that ‘silver doping’ allowed for partial bandgap tunability from 1.91 eV to 2.05 eV, increasing the photoluminescence (PL) lifetime from 0.990 ns to 1.187 ns, and, finally, contributing to the structural stability when examining the aging effect via X-ray diffraction. Then, through the analysis of the intermolecular interactions based on the solubility parameter, we explain the solvent engineering process in relation to the solvent trapping phenomena in CsPbI2Br thin films. However, silver doping may induce a defect morphology (e.g., a pinhole) during the formation of the thin films.

The functionalization of conductive inks has been carried out through the decomposition of hydrogen peroxide (H2O2) onto the surface of silver nanoparticles (AgNPs). The ink prepared using this eco-friendly chemical reagent has been characterized structurally, chemically, and morphologically, showing the presence of stable AgNPs with suitable properties as well as the absence of residual contamination. The electrical conductivity of such a solution-processable ink is evidenced for patterns designed on flexible photographic paper substrates, using a refillable fountain pen that is implemented as a printing mechanism for the fabrication of simple printed circuit boards (PCBs). The functionality and durability of the tested systems are demonstrated under various mechanical constraints, aiming to basically reproduce the normal operation conditions of flexible electronic devices. The obtained results indicate that the implementation of these AgNP-based inks is relevant for direct applications in inkjet printing technology, thus paving the way for the use of greener chemicals in ink preparation.

В роботі проведено аналіз зносу різців та виявлено, що більшість з них придатна для використання, так як форма твердосплавного наконечника не дуже змінилась та може використовуватися для подрібнення асфальто-бетонної суміші. Була розроблена та запропонована методика відновлення хвостової частини корпусу різців. Маршрут відновлення наступний: 1. Очищення різця. 2. Нагрівання пропаново-кисневим полум’ям хвостової частини різця. 3. Пластичне деформування корпусу різця у штампі. 4. Охолодження на повітрі. 5. Контрольне вимірювання зміни розмірів. Рекомендована температура термообробки під пластичну деформацію залежить від концентрації вуглецю і легуючих елементів сталі та знаходиться в діапазоні температур від 800 до 1280°С, час нагріву 1,33 хв. Попередньо перед деформацією, корпус різця нагрівали за допомогою пропаново-кисневого полум’я. Осадку проводили в закритому штампі за допомогою спеціального пуансона. В матриці розміщували головку різця, на яку встановлювалась направляюча з пуансоном. Відпрацьована технологія відновлення хвостової частини різця роздаванням. За запропонованою технологією відбувається роздавлюваня хвостової частини корпусу різця від 0,04 мм до 0,73 мм на сторону. Таким чином відновлюються різці дорожніх фрез майже до розмірів нової деталі, що дає змогу повторного використання.

The rapid development of educational technologies requires the active involvement of new means and effective teaching methods. One of the innovative tools of learning in the field of robotics is the use of robot simulators in the educational process, which open up many opportunities for better assimilation of knowledge and development of practical skills among students. Robot simulators are software complexes that allow you to visualize and simulate the behavior of real robots. With these tools, students can: • program robots in a virtual environment, test code and debug without the risk of damaging real equipment; • to study robotics and the principles of robot operation, exploring different types of sensors, actuators and algorithms of robot behavior; • to solve problems in various fields, such as production automation, logistics, construction, etc.; • practices your skills in a safe and controlled environment. Among the benefits of using robotic simulators are next: • availability for a large number of students, as simulators are much cheaper than real jobs; • safety, as the virtual environment eliminates the risks associated with working with real robots; • flexibility that allows students to work at their own pace, explore different scenarios and experiment with different parameters; • interactivity with a realistic 3D-environment and visualization. This work presents an overview and analysis of software that allows modeling robot control systems and simulating their operation for various algorithms. A review and analysis of the proposed software tools for simulating robotic systems, which are used to teach bachelor's and master's degree students in the specialties of "Computer Science", "Information Systems", "Industrial Mechanical Engineering" and "Applied Mechanics" and have proven their effectiveness and effectiveness in distance learning at the Kyiv National University of Construction and Architecture.

The purpose of the proposed article is the analysis of the principles of the formation of the workload on the executive bodies of construction machines and technological equipment, which is due to the need for their improvement in order to improve the energy and technological indicators of technological processes.The methodology is based on search, research and creative approaches. The methods of development analysis, patent search, synthesis of technical solutions, simulation modelling was used. Scientific novelty. The study of various approaches to ensuring the implementation of the working movements of executive bodies of construction machines and mechanized technological equipment, the analysis of technical solutions allowed to substantiate the directions of development of drives of construction machines to ensure the necessary laws of movement of executive elements. The authors proposed constructive solutions for synthetic drives of construction machines and equipment, proposed energy-saving approaches aimed at reducing energy consumption. Research results. The article deals with important issues of analyzing the formation of loads on executive bodies of construction machines and equipment. Synthesized constructive solutions obtained in the course of patent research, analysis of modern technical solutions, rational technical design and expert evaluation are presented. A technical solution is proposed to ensure the implementation of adaptive feed in a hydraulic power drive, which can be used in the modernization of existing drives of construction machines and moving parts of mechanized technological equipment.

The purpose of the proposed article is the development and construction of a mechanized mobile platform for serving people, which is caused by the need to increase the safety of the operation of such technical means, in particular, in the case of the need for mass customer service. The methodology is based on search, research and creative approaches. The methods of development analysis, patent search, synthesis of technical solutions, simulation modelling was used. Scientific novelty. The study of the features of various approaches to the creation of effective mechanized moving platforms, the analysis of solutions and the dynamics of patenting made it possible to substantiate the directions of development of technical solutions and the prospects of developments. The authors proposed constructive solutions for mobile platforms, developed approaches to the technical implementation of increasing the safety of their operation, proposed energy-saving approaches aimed at reducing the energy consumption of mechanized means, which is especially relevant in the mass implementation of platforms for serving people. Research results. The article solves important safety issues of human service, in particular in the entertainment industry through the development of structural parts, drives and rules for the operation of mechanized moving platforms. Synthesized constructive solutions obtained in the course of patent research, analysis of modern technical solutions, rational technical design, and expert evaluation are presented. It was determined that the safety of the operation of mechanized moving platforms, which are intended for the transport of people in the field of tourism, depends on effective approaches to the design and components of the technical system in the form of a moving platform, its structural components, elements of its mechanism and the drive system as a whole, which with the optimization of technical indicators the stability of the overall system, the smoothness of movement and braking of the platform, the optimization of the materiality of the structure in total allow to have a qualitative effect on improving the safety of human operation.

The production of concrete mixes, along with their use in the production of building materials and structures, is one of the key processes in the construction industry during the construction, restoration and repair of buildings and structures. Because of this, the need to create modern concrete mixing plants that will meet the requirements of minimum energy consumption and maximum productivity of concrete mixture production is an urgent task. Not only the main operations, which include the dosing of the components of the mixture and their mixing, but also the maintenance operations, namely operations that ensure the timely movement of the components of the concrete mixture from warehouses to the main technological equipment, affect the set rhythm of the concrete mixture production. Conveyors of various types and designs are used to move bulk materials, such as crushed stone and sand. For the rational selection of such equipment in accordance with the characteristics of the cargo to be transported, knowledge of the types of conveyors, their structures and parameters, understanding of operation issues and methods of parameter calculation are required. In addition, it is worth paying attention to the following parameters: maximum cargo transportation productivity, low energy consumption per unit of moved products, low metal content of the structure. The work reviewed the most common designs of conveyors used to move bulk materials in concrete mixing plants, analyzed the disadvantages and advantages of conveyors, as well as technical parameters. As a result, the predominant directions for the use of belt and plate conveyors at construction enterprises were determined. The advantages of belt conveyors, which contribute to their widespread distribution, are high productivity, simplicity of design, reliability, quiet operation, low specific power consumption. When choosing a conveyor, it is recommended to choose the equipment with the highest productivity and the lowest power of the drive motors, however, the performance should be clearly related to other technological equipment.

Reach stackers are efficient and maneuverable machinery for an overload of overall containers in cargo terminals and ports today. Such machinery design determines the practical interest of the engineering industry specialists. However, the lack of information in open sources about structural or kinematic diagrams of equipment control mechanisms and recommendations for their calculation does not allow an effective approach to the creation and update of reach stackers. We developed the design procedure of the reach stacker control system, which considers the kinematic and geometric parameters of the container spreader, as a result of the conducted research. It can be used in the design stages of mechanisms for spreader lateral displacement, extension of the spreader sections, spreader inclination in the vertical plane, container fixation by spreader, spreader rotation, lifting-lowering and telescoping of the boom, as well as during the real operation modes of reach stackers in cargo terminals and ports.

Loading and unloading works are an integral part of the construction process. Cranes of various types were mostly use to perform these works. To ensure trouble-free operation and increase the reliability of cranes, when calculating structures and components of their working equipment, it is important to take into account dynamic loads, which are several times higher than static loads. Elements of dynamic loads in the crane suspension are its elastic components (flexible traction bodies) - ropes. The process of lifting a load from a rigid base and picking it up is considered, which divided into three stages: the first is the selection of clearances and the tension of the ropes; the second is the pre-opening stage of lifting the load; the third is the post-detachment stage of lifting the load. For each stage, the initial conditions accepted, the differential equations of the movement of loads compiled, their solution given taking into account many factors, and expressions derived for determining the forces in the load suspension. At the first stage, the duration of the gap selection (tension of the ropes) is determined, at the second stage, the speed of separation of the load from the base is determined, at the third stage, the maximum force in the elastic element determined. The method of determining the forces in the suspension of the load, the duration of the selection of clearances (tension of the ropes), the speed of separation of the load from the base, and the maximum force in the elastic element presented in the work allows you to significantly simplify the solution of complex equations, to determine simple expressions and to determine them with sufficient accuracy for practical calculations values.

The main of the problems of the development of two-link manipulators with an angular coordinate system is the lack of effective and universal control systems capable of implementing energy-intensive modes of movement. This is due to the design features of the pointer system of such manipulators and the methods of their use. During the operation of the manipulator, significant dynamic loads occur in its drive system, which create oscillations of the mechanical system and reduce the accuracy of work. The control system must also effectively compensate for such dynamic variations. Dynamic equations of motion used to build manipulator control controllers, which allow taking into account various features of using manipulators. These mathematical models necessarily contain one of the characteristics in the form of the combined moment of inertia of the mechanical system, which is important in the calculation of differential equations and the determination of kinematic parameters of motion. In this article, the combined moments of inertia of the boom system of a two-link manipulator with an angular coordinate system are determined. A study was carry out and it shown that the nature of the change in the combined moments of inertia influenced by the modes of movement of the boom system links. The results of the study showed that the combined moment of inertia of the boom system of the manipulator is not a constant value, which does not change uniformly under special operating conditions of the machine. To determine the combined moments of inertia, the method of bringing the kinetic energy of the moving system to the drive mechanism was apply. This is relevant, because in the future it will be necessary to adjust the unevenness of the movement of the manipulator links by the drive itself. The study was conduct for a typical linear motion mode and a motion mode with a change in speed along a parabolic trajectory.

Despite significant progress in preventing and treating Tuberculosis (TB), it continues to be a leading cause of death worldwide. This is largely attributed to the rise of drug-resistant strains, notably Multidrug-Resistant Tuberculosis (MDR-TB) and Extensively Drug-Resistant Tuberculosis (XDR-TB). These resistant forms pose significant challenges, undermining the progress made against TB and necessitating innovative approaches for their management. This study enhances the Discrete VSEIT epidemiological model for TB by incorporating the dynamics of MDR/XDR-TB. The model incorporates distinct compartments for susceptible, exposed, infected, and resistant individuals receiving either first- or second-line treatments, in addition to those actively undergoing treatment. It considers natural population growth, the interactions among these groups, and the impact of treatment by chemoprophylaxis. The fundamental reproduction number ($\mathcal{R}_0 $) is determined by the mean of the next-generation matrix method. Investigation of the Stability of both the Disease-Free Equilibrium (DFE) and the Epidemic Equilibrium (EE) validate their global asymptotic stability. Model parameters are based on TB case data from India and Russia, two high-burden countries, from 2000 to 2022. The results indicate $\mathcal{R}_0 > 1$ for India and $\mathcal{R}_0 < 1$ for Russia. analyzing the sensitivity and numerical simulations show that increasing chemoprophylaxis treatment for exposed individuals decreases the advancement to multidrug-resistant, infectious, and extensively drug-resistant states. Additionally, BCG vaccination of children enhances immunity against TB and reduces disease transmission to healthy individuals, contributing to overall disease reduction. TB remains a more significant issue in India compared to Russia.

The impact of N2 purging in the CdS deposition bath and subsequent N2 annealing is examined and contrasted with conventional CdS films, which were deposited without purging and annealed in ambient air. All films were fabricated using the chemical bath deposition method at a temperature of 80 °C on fluorine-doped tin oxide glass slides (FTO). N2 purged films were deposited by introducing nitrogen gas into the deposition bath throughout the CdS deposition process. Subsequently, both N2 purged and un-purged films underwent annealing at temperatures ranging from 100 to 500 °C for one hour, either in a nitrogen or ambient air environment. Photoelectrochemical (PEC) cell studies reveal that films subjected to both N2 purging and N2 annealing exhibit a notable enhancement of 37.5% and 27% in ISC (short-circuit current) and VOC (open-circuit voltage) values, accompanied by a 5% improvement in optical transmittance compared to conventional CdS thin films. The films annealed at 300 °C demonstrate the highest ISC, VOC, and VFB values, 55 μA, 0.475 V, and −675 mV, respectively. The improved optoelectrical properties in both N2-purged and N2-annealed films are attributed to their well-packed structure, enhanced interconnectivity, and a higher sulfur to cadmium ratio of 0.76 in the films.

This article investigates resistive random access memory (ReRAM) crossbar memory arrays, which is a notable development in non-volatile memory technology. We highlight ReRAM’s competitive edge over NAND, NOR Flash, and phase-change memory (PCM), particularly in terms of endurance, speed, and energy efficiency. This paper focuses on the architecture of crossbar arrays, where memristive devices are positioned at intersecting metal wires. We emphasize the unique resistive switching mechanisms of memristors and the challenges of sneak path currents and delve into the roles and configurations of selectors, particularly focusing on the one-selector one-resistor (1S1R) architecture with an insulator–metal transition (IMT) based selector. We use SPICE simulations based on defined models to examine a 3 × 3 1S1R ReRAM array with vanadium dioxide selectors and titanium dioxide film memristors, assessing the impact of ambient temperature and critical IMT temperatures on array performance. We highlight the operational regions of low resistive state (LRS) and high resistive state (HRS), providing insights into the electrical behavior of these components under various conditions. Lastly, we demonstrate the impact of selector presence on sneak path currents. This research contributes to the overall understanding of ReRAM crossbar arrays integrated with IMT material-based selectors.

Analyzing objects concerning their periodic behavior is mostly performed with inertial measurement units (IMUs) or global navigation satellite system (GNSS) sensors fixed to its surface. For connecting observations, sensors have to be assigned to the same reference frame in space and time as a prerequisite. Using light detection and ranging (LiDAR) observations enables contactless, time-synchronized, and spatially connected data points within a single sensor. Therefore, common signal properties are further analyzed in the spectrum to find connections and similarities between observations. Since observations are spatially continuous we can discretize them and traditionally process them. However, the time domain offers a diversity of ways to simultaneously estimate frequencies and continuously model properties at different spatial locations. Within this work, we exploit the potential of processing LiDAR data in the time domain to make use of the sensor’s contactless observations and its sampling rate in space and time. Consecutive points and their spatial neighborhoods are used to implement temporal as well as spatiotemporal connections to directly model oscillations in 2-D space. Moreover, we compute an uncertainty of estimated variables to qualify our solution. Consequently, our approach offers the opportunity to describe as well as evaluate movements and vibrations of spatially connected areas.

Industrial control systems are facing ever-increasing security challenges due to the large-scale access of heterogeneous devices in the open Internet environment. Existing anomaly detection methods are mainly based on the priori knowledge of industrial control protocols (ICPs) whose protocol specifications, communication mechanism, and data format are already known. However, when these knowledge are blank, namely, unknown ICPs, existing methods become powerless to detect the anomaly data. To tackle this challenge, we propose a multigranularity feature automatic marking-based deep learning method to classify unknown ICPs for anomaly detection. First, to obtain the feature sequences without priori knowledge assisting, we propose a multigranularity feature extraction algorithm to extract both byte and half-byte information by fully utilizing the intensive key information in the header field of the application layer. Then, to label the feature sequences for deep learning, we propose a feature automatic marking algorithm that utilizes the inconsistency feature sequences to dynamically update the feature sequence set. With the labeled feature sequences, we employ deep learning with 1-D convolutional neural network and gated recurrent unit to classify the unknown ICPs and realize anomaly detection. Extensive experiments on two public datasets show that both the accuracy and precision of the proposed method reach above 98.4%, which is better than the three benchmark methods.

Autonomous navigation has become a topic of immense interest in robotics in recent years. Light detection and ranging (LiDAR) can perceive the environment in 3-D by creating the point cloud data that can be used in constructing a 3-D or high-definition (HD) map. Localization can be performed on the 3-D map created using a LiDAR sensor in real-time by matching the current point cloud data on the prebuilt map, which is useful in the GPS-denied areas. GPS data is inaccurate in indoor or obstructed environments, and achieving centimeter-level accuracy requires a costly real-time kinematic (RTK) connection in GPS. However, LiDAR produces bulky data with hundreds of thousands of points in a frame, making it computationally expensive to process. The localization algorithm must be very fast to ensure the smooth driving of autonomous vehicles. To make the localization faster, the point cloud is downsampled and filtered before matching, and subsequently, the Newton optimization is applied using the normal distribution transform to accelerate the convergence of the point cloud data on the map, achieving localization at 6 ms per frame, which is 16 times less than the data acquisition rate of LiDAR at 10 Hz (100ms per frame). The performance of optimized localization is also evaluated on the Kitti odometry benchmark dataset. With the same localization accuracy, the localization process is made five times faster. LiDAR map-based autonomous driving on an electric vehicle is tested in the TiHAN testbed at the IIT Hyderabad campus in real-time. The complete system runs on the robot operating system (ROS). The code will be released at https://github.com/abhishekt711/Localization-Nav.

This article presents a novel method for accurate online extraction of semiconductor ON-state resistance in the presence of measurement noise. In this method, the ON-state resistance value is extracted from the measured ON-state voltage of the semiconductors and the measured load current. The extracted ON-state resistance can be used for online condition monitoring of semiconductors. The proposed method is based on the extraction of selective harmonic content. The estimated values are further enhanced through an integral action that increases the signal-to-noise ratio, making the proposed method suitable in the presence of noisy measurements. The efficacy of the proposed method is verified through simulations in the MATLAB/Simulink environment, and experimentally. The estimated ON-state resistance values from the online setup are compared to offline measurements from an industrial curve tracer, where an overall estimation error of less than 1% is observed. The proposed solution maintains its estimation accuracy under variable load conditions and for different temperatures of the device under test.

Tunable diode-laser absorption spectroscopy (TDLAS) sensors have shown to be applicable to, e.g., temperature and pressure measurements in gases. These parameters are indispensable in modern avionics. Even though these systems performed well in laboratory or closed environments, the harsh conditions of avionic flight introduce sources of error. To cope with these challenges, altered variants of the classical direct TDLAS may be taken into consideration. Here, we investigate the differences between an all fiber direct TDLAS and a Mach-Zehnder-based amplitude modulated TDLAS variant. We are able to demonstrate the increased noise immunity of the amplitude modulated system as well as the use of the oxygen A-band for the use as an optical pressure detector.

The performance enhancement of an inverter-based grid-connected system necessitates a fast and accurate dynamic response in terms of estimating three-phase grid voltage attributes. The synchronous reference frame phase-locked loop (PLL) and/or the frequency-locking (i.e., frequency-locked loop) approaches are widely used in practical applications. However, due to the phase/frequency feedback loops, the aforementioned parameter estimation schemes may experience instability and provide a slow dynamic response. This work presents a PLL-less grid synchronization solution for three-phase applications to counter the slower dynamic response and demonstrate better immunity against the nonideality of a three-phase grid. In order to remove even and odd-order harmonics and extract the fundamental frequency positive sequence (FFPS), the proposed method employs a combination of band pass filters (CBPFs). Additionally, a novel frequency estimation algorithm is developed, which accurately estimates the angular three-phase grid frequency. Furthermore, the phase angle and amplitude are adaptively estimated using an off-line error-resolving approach, which is derived from the transfer function of the proposed prefiltering solution. Finally, the experimental findings validate the robustness of the current proposal.

Common additive manufacturing (AM) methods use metal powder feedstock. The properties of the metal powder, such as particle size distribution (PSD), morphology, and presence of surface oxides or other contaminants, significantly impact the quality of the built part. Microwave materials characterization techniques potentially offer effective means by which to evaluate such metal properties. To assess sensitivity of microwave signals to the properties of metal powder used in AM, different types of metal powder were incorporated into resin composite samples, whose dielectric and magnetic properties were then measured using the well-known completely filled-waveguide technique at the Ka-band (26.5–40 GHz) and V-band (50–67 GHz). These measurements revealed that microwave signals are sensitive to small (~0.5%) changes in the metal powder volume fraction. It was also found that the resin powder composites exhibited diamagnetic properties and could be accurately modeled using effective media theories which consider both the dielectric and magnetic properties. The findings open the door for future investigations by which optimized techniques can be devised to do the same in an in-line manner during the AM process.

3-D brain electrical impedance tomography (EIT) holds great promise for real-time noninvasive imaging of various brain injuries. However, a reference method for selecting high-performance electrode configurations has not been proposed. In this article, the optimization of electrode layout, stimulation and measurement protocols, and the number of electrodes are sequentially performed. The signal quality and image reconstruction performance of simulated perturbations in four cortical regions are evaluated with various levels of noise taken into consideration. The results showed that, considering cost and convenience, the best number of electrodes is 20, which should be placed in the suboccipital and central vertex regions as needed. Electrodes with large spacing at different heights are mainly the driving electrodes, and the potential is collected in the appropriate adjacent channels. These principles are expected to provide general guidance for the electrode configuration methods of 3-D brain EIT in clinical applications.

We present an assessment of simulated lidar point clouds based on different phenomenological range-reflectivity models. In sensor model development, the validation of individual model features is favorable. For lidar sensors, range limits depend on surface reflectivities. Two phenomenological feature models are derived from the lidar range equation, for clear and adverse weather conditions. The underlying parameters are the maximum ranges for best environment conditions, based on sensor datasheets, and a maximum range measurement for attenuation conditions. Furthermore, an assessment of different feature models is needed, similar to unit tests. Therefore, resulting point clouds are compared with respect to the total number of corresponding points and the number of points with no correspondences for pair-wise cloud comparison. Applications are presented using a point cloud lidar model. Results of the point cloud comparison are demonstrated for a single scene or time step and an entire scenario of 40 time steps. When a reference point cloud is provided by the sensor manufacturer, feature validation becomes possible.

This article proposes an enhanced fusion technique to improve the accuracy of the state estimation of a navigational system. The smooth variable structure filter (SVSF) is examined to estimate the system’s state under model uncertainty. Its combination with the unscented Kalman filter (UKF) to acquire better navigational accuracy while being robust to the system’s modeling uncertainty is investigated. The proposed hybrid method is compared with the extended Kalman filter (EKF), the UKF, and the SVSF. The proposed algorithms fuse an inertial measurement unit (IMU) with the Global Positioning Systems (GPS) measurements to obtain the vehicle’s state. Experimental results are compared to a commercial off-the-shelf (COTS) solution. It is shown that all filtering strategies have similar performance in the absence of large-magnitude noise and model uncertainties. When injecting modeling uncertainties, the performance of the UKF degrades, and that of the EKF goes out of bounds. On the other hand, increasing the covariances of the measurement and dynamics noise sequences causes the path of the SVSF to become nonsmooth and roughly oscillates around the true path. The proposed integrated UK-SVSF algorithm achieves the following objectives: first, using the Kaman-based filter enhances the optimality of the filter to GPS/IMU dynamics and measurements noise. Second, using the UKF reduces the estimation error by eliminating the first-order linearization step. Finally, using the SVSF enhances the estimate’s robustness to model uncertainty. Results reveal that, in the presence of both large-magnitude noise and model uncertainties, the UK-SVSF gives an enhanced estimation performance.

Abnormal fluid buildup in the lungs, termed pulmonary edema (PE), is a result of congestive heart failure. It is a life-threatening condition, and early detection and prompt treatment can help save lives. In this article, we demonstrate the feasibility of using a microwave sensor to monitor changes in lung water content and hence detect PE. The research paper utilizes a combination of the Debye and Maxwell models, along with the Cole–Cole equation, to evaluate alterations in the dielectric properties and conductivity of lung tissue. By incorporating elements such as air and water found within the tissue, this dielectric model has been employed to foresee how lung tissues behave when subjected to different levels of hydration and inflation. A printed antenna resonating at 2.4 GHz was designed to work as a sensor. The static dielectric parameters of lung tissue at various water volume fractions were calculated at 2.4 GHz using the Debye–Maxwell model. These parameters were substituted in the Cole–Cole equation to calculate the dielectric constant of lung tissue for different levels of water in the lungs. These values were then substituted in the simulation environment, where the sensor is placed on blocks modeling the human thorax. This work is a first of its kind where the dielectric parameters at different levels of hydration have been previously estimated using mathematical models and substituted accordingly in the modeling environment to test the possibility of detection of PE with high precision. It was observed that the magnitude of the reflection coefficient values changes with increasing water volume fraction, making the microwave method of detection of PE feasible and a reliable technique.

Frequency scanning interferometry (FSI) has become a popular method for long-range, targetbased, distance measurements. However, the cost of developing such systems, particularly the electronic components required for high-speed data acquisition (DAQ), remains a significant concern. In this article, we present a cost-effective, FPGA-based real-time DAQ system specifically designed for FSI, with a focus on long absolute distance measurements. Our design minimizes the use of third-party intellectual property (IP) and is fully compatible with the Xilinx FPGA 7 series families. The hardware employs a 160-MS/s, 16-bit dual-channel ADC interfaced to the FPGA via a low-voltage differential signaling (LVDS). The proposed system incorporates an external sampling clock, referred to as the K-clock, which linearizes the laser’s tuning rate, enabling optical measurements to be sampled at equal optical frequency intervals rather than equal time intervals. Additionally, we present the design of a high-speed, 160-MS/s ADC module for the front-end analog signal interface and the LVDS connection to the chosen FPGA. We demonstrate that the digitized data samples can be efficiently transmitted to a polarization controller (PC) application via a USB interface for further processing.

In this work, we demonstrate the preparation of easy-to-fabricate nanogranular strontium ferromolybdate/strontium molybdate core-shell ceramics and examine their properties, including tunnel magnetoresistance, magnetic field sensitivity, and temperature coefficient of the tunnel magnetoresistance. The tunnel magnetoresistance of nanogranular strontium ferromolybdate/strontium molybdate core-shell ceramics was modeled, yielding values suitable for magnetoresistive sensor applications. Such structures possess a narrow peak of magnetic flux sensibility located at about 80 mT. For magnetic flux measurement, single-domain granules with superparamagnetic behavior should be applied. The predicted TMR magnetic flux sensitivities for granules with superparamagnetic behavior amount to about 7.7% T−1 and 1.5% T−1 for granule sizes of 3 nm and 5 nm, respectively. A drawback of the tunnel magnetoresistance of such nanogranular core-shell ceramics is the unacceptably large value of the temperature coefficient. Acceptable values, lower than 2% K−1, are obtained only at low temperatures (less than 100 K) or large magnetic flux densities (exceeding 6 T). Therefore, a Wheatstone bridge configuration should be adopted for magnetoresistive sensor design to compensate for the effect of temperature.

Microplastics (MPs) are global pollutants found in various environmental compartments, including oceans, freshwater bodies, soils, and air. Their persistence and potential to adsorb heavy metals raise significant concerns regarding water quality and ecosystem health. Understanding the interaction between MPs and heavy metals is crucial for assessing environmental risks and developing remediation strategies. In this study, we use electroanalytical techniques to investigate the adsorption of heavy metal ions— Cr³⁺, Zn²⁺, and Ni²⁺—by polystyrene MPs with different surface functionalizations: carboxyl, amino, and unfunctionalized. We conducted electrodeposition of metal ions on a gold ultramicroelectrode both before and after mixing with MPs. Following this, we used anodic stripping voltammetry to measure the change in the electrodeposited charge (ΔQ). This charge difference, observed before and after the interaction of ions with MPs, was analyzed to understand the adsorption kinetics and dynamics. Our experiments revealed that carboxyl-functionalized MPs exhibited the highest ΔQ due to strong electrostatic attraction with the metal ions, with values 1.67 ×, 1.50 ×, and 1.22 × greater than those for amino-MPs for Cr³⁺, Zn²⁺, and Ni²⁺, respectively. Amino-MPs displayed considerable ion adsorption, suggesting poor electrostatic repulsion between two positively charged entities. Interestingly, unfunctionalized MPs, which had a negative surface charge similar to carboxyl-MPs, showed different adsorption characteristics, with lower ΔQ values for all metal ions. This study underscores the significant role of surface functionalization on the adsorption efficiency and kinetics of heavy metal ions by MPs. It also demonstrates the utility of electroanalytical techniques in understanding metal ion-MP interactions, offering insights into potential environmental impacts and remediation strategies, as well as in developing electrochemical sensors for detecting heavy metal ions adsorbed on MPs.

Electroanalysis is a type of analytical method used to study an analyte by measuring its electrical properties in an electrochemical cell. It has been widely used because it is a relatively simple and inexpensive technique, has a low detection limit and is able to measure original electrical signals. Electroanalysis has advanced with the development of nanotechnology, offering new opportunities for analysis. Scanning electrochemical microscopy (SECM) is a probe-based surface analysis instrument that enables real-time surface and interfacial analysis with spatial resolution in an electrochemical environment. In this review, we focus on the use of nanoscale SECM for improved electroanalysis. After introducing the fabrication, characterization, and modification of nanoelectrodes, which are the key to enabling nanoscale SECM, we introduce the instrumentation and fundamental principles of SECM. Several examples are provided to illustrate the advanced electroanalysis of photo-electrocatalysts and biosystems based on nanoscale SECM, which will be utilized as a more powerful electroanalytical tool in the future when combined with other analytical instruments.

Understanding the molecular redox state is crucial for investigating chemical activities involving electron exchange, particularly in optical electrochemistry. Methyl viologen (MV) is commonly employed as a redox mediator and electron acceptor, exhibiting three distinct redox states (MV0, MV+, and MV2+), each characterized by a unique molecular structure and Raman spectrum. Utilizing surface-enhanced Raman spectroscopy (SERS), we explore the discrete molecular redox states of MV on shell-isolated nanoparticles (SHINs), which are gold nanoparticles (AuNPs) coated with silica shells of varying thicknesses, ranging from 1 to 10 nm. Our study, employing 532 nm excitation, reveals that all three redox forms of MV are sporadically observed on the metallic surfaces of AuNPs. However, the radical cation (MV+) state is predominantly detected on the silica surfaces of the SHINs, irrespective of the shell thickness. This consistency across different shell thicknesses suggests that electromagnetic (EM) effect predominantly contributes to the Raman enhancement in shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), rather than enhancement via electron transfer. If electron transfer were induced by laser excitation, varying redox species would likely appear dependent on shell thickness. Given the absence of external perturbation such as applied potential or reducing agents, we believe our findings can provide a crucial reference for future studies using MV as a redox state-sensing probe. Furthermore, our results demonstrate the efficacy of SHINs as a robust nano-sensing platform that efficiently prevents direct contact with the metallic surface and unwanted reactions.

The research proposes and investigates an extraordinarily sensitive, label-free WaveFlex biosensor utilizing optical fiber technology for the detection of Staphylococcus aureus (S. aureus), a common foodborne bacterium. The WaveFlex biosensor (plasmon Wave based Flexible optical fiber Biosensor) is based on a novel flexible tapered single-mode fiber structure, utilizing gold nanoparticles (AuNPs) to trigger the phenomenon of localized surface plasmon resonance (LSPR). Additionally, the sensitivity is further enhanced using chitosan-coated iron(III) oxide nanoparticles (Fe3O4–CS NPs) and tungsten disulfide quantum dots (WS2-QDs). The optical fiber surface is functionalized with antibodies to achieve specific detection of S. aureus. For S. aureus concentrations at 1 × 108 CFU/mL (colony-forming units per milliliter), the sensor's maximum sensitivity of 2.74 nm/lg (CFU/mL), and a detection limit (LOD) of 6.67 CFU/mL. This ultra-sensitive biosensor holds great potential for widespread applications in various fields, including disease detection, medical diagnostics, and food safety inspection.

In this study, we synthesized Co2P nanoparticles using a solid-state phosphorization method and evaluated the electrocatalytic response to glucose oxidation reaction (GORs). The influence of synthesis conditions on the particle size, morphology of Co2P species and formation of byproducts is discussed. A lower molar ratio of the phosphorus precursor leads to a decrease in the generation of byproducts. In addition, the calcination temperature and time greatly influence the purity level of the Co2P species and its particle size. Thus, we obtained three pure Co2P nanoparticles with different sizes and morphologies. Significant differences in their electrocatalytic activity against the GOR are observed depending on the size of the particles, being the smaller ones the most efficient. Based on Tafel analysis, a higher catalytic activity was observed for the carbon fibre (CF)/Co2P composite compared to Co2P, which presented a greater onset potential and low response in current density. Tafel slopes close to 120 mV/dec were obtained for both materials, indicating that the mechanism is independent of the type of Co2P-based material used. Finally, the performance of the GCE/CF/Co2P sensor was demonstrated by amperometric measurements, with a sensitivity of 409 µAmM-1cm-2, a linear range between 39.4 µM and 150 µM, and a detection limit of 0.97 µM, analytical characteristics better than those obtained for other cobalt phosphide-based sensors reported in the literature. In addition, the GCE/CF/Co2P sensor shows excellent selectivity and demonstrated to be competitive compared to other Co-based non-enzymatic glucose sensors.

We evaluate different methods to detect benzene at a parts-per-billion level regarding their potential to be used in a wearable sensor. Benzene is a carcinogenic molecule, regarded as a major health threat by the World Health Organization. A wearable sensor is necessary to detect leaks immediately, but it is challenging to achieve such low limits of detection and quantification, even with laboratory equipment. A wearable sensor must, in addition to good selectivity and sensitivity, meet stricter requirements of size, weight, temperature, repeatability, and power consumption. We conclude that the most promising techniques for a wearable sensor are either infrared photoacoustic spectroscopy near 14.8 μm, or a photoionization detector combined with one of three selective devices: micro-gas chromatography, cavitands, or catalytic filters (WO3, for example). Ultraviolet photoacoustic spectroscopy may also be a suitable future technique for a wearable benzene sensor when efficient LEDs and lasers become available at many UV-C wavelengths.

Ensuring the long-term stability of screen-printed (SP) reference electrodes (REs) is increasingly essential because a major technical challenge in fabricating electrochemical sensors using screen printing is preparing an RE with a stable potential as it scales down in size. In this study, we fabricated SP electrodes that exhibit long-term stability in voltammetric and potentiometric experiments. The SP electrodes consisted of carbon working electrodes, a carbon counter electrode, an Ag/AgCl RE, and an ion-selective electrode (ISE) for detecting nitrate ions. The Ag/AgCl RE featured an electrolyte layer, a hydrophobic junction layer, and a small hole, collectively contributing to its long-term stability. This design achieved potential stability with minimal drift over extended periods in both 0.01 M PBS (pH 7.4) and 0.1 M Bis-tris (pH 6.5) buffer solutions. Additionally, the SP Ag/AgCl RE exhibited relatively low potential drift in the presence of various chemicals and different pH solutions. We analyzed the electrochemical behavior of two redox species, Fe(CN)63-/4− and Ru(NH3)62+/3+, using cyclic voltammetry and electrochemical impedance spectroscopy techniques at the SP electrodes. Potentiometric experiments confirmed the sensitivity, long-term stability, and selectivity of the SP ISE for nitrate ion detection, even in the presence of interfering ions.

In this study, cupric oxide nanowires (CuO NWs) on patterned interdigitated electrodes (PIEs) used as ozone (O3) gas sensors, were successfully fabricated using thermal oxidation and the microelectromechanical systems (MEMS) technique. After the thermal oxidation process, CuO NWs with different heights and densities were fabricated using a pure copper seed layer with a thickness ranging from 0.5 μm to 2 μm. In this experiment, a low temperature, low concentration, and repeatable CuO NWs gas sensor was fabricated, which can detect O3 gas at a low concentration of 50 ppb and low temperature of 100°C with a high sensor response (40%). The concentration response of this gas sensor shows an increasing linear trend, with an increase of O3 concentration in the range of 50 ppb - 300 ppb. Additionally, the results indicated that this CuO NWs gas sensor is more selective for O3 than CO, CO2, C2H5OH, C3H6O, NO2, or NH3. While CuO has been less studied in O3 detection compared with other semiconducting metal oxide materials, CuO NWs show potential applications in gas sensing devices for low-temperature and low-concentration O3 environmental monitoring.

Nanopores play essential roles in biological processes, such as ion channels and pumps in cellular membranes, and in technological applications such as DNA sequencing. Advancements in nanofabrication techniques have enabled the routine integration of nanopores into solid-state devices, resulting in a plethora of analytical applications. This review explores recent developments in nanopore-enabled electrochemical systems, which have transcended traditional resistive pulse sensing to offer novel capabilities in single-entity studies, stimulus-responsive gating, and point-of-care diagnostics. We highlight recent studies on the design and utility of nanopore electrode arrays, which serve as nanocontainers capable of isolating and analyzing single entities, and extend the discussion to hierarchically organized, stimulus-responsive systems that regulate species transport across nanopores, enriching analytes for ultrasensitive detection. In addition, we review the utilization of probe-assisted nanopore sensing, demonstrating its efficacy in selectively binding and detecting target molecules and ions. Finally, we outline future directions for nanopore-based systems to enhance robustness, achieve high-throughput analysis, and incorporate artificial intelligence for materials design and data analysis, promising transformative impacts on diagnostics and biological research.

Diabetes disease caused by hyperglycemia has many complications, including cardiovascular disease, kidney disease and visual impairment. Effective and stable platform of enzyme-free glucose detection is significant important for the monitoring of diabetes disease. In this work, uniform single MXene layers were fabricated with large scale through HCl/LiF etching and tapered gold nanostructures (AuTNs) was electrodeposited on the MXene layers. The AuTNs with three-dimensional conical apex on the MXene layers can effectively increase the specific surface ratio and active sites. The composite materials of AuTNs and MXene layers assembled on the glassy carbon electrode (GCE) can significantly increase the electrochemical performance during glucose detection. The modified electrode of AuTNs/MXene/GCE shows good linearity from 0.1 nM to 10.0 mM, low limit of detection (LOD) of 1.43 nM and fast response time of 1.0 s, exhibiting high sensitivity, good stability and high selectivity for glucose during electrochemical detection. The high performance of the modified electrode provides promising potential application in enzyme-free sensor for the electrochemical detection of glucose.

The presence of nitrite, a prevalent contaminant in natural environments, presents a significant environmental and human health concern. Hence, it is imperative to develop a sensor with the ability to quantitatively detect nitrite. This study focuses on the design and development of i) probe 1: tilted fiber Bragg gratings (TFBGs) and ii) probe 2: fiber optic tip-based plasmonic sensors utilizing ion-imprinted polymers. The concentration of nitrite was assessed at various levels using both sensing configurations. The outcomes indicated that the TFBGs-based sensor exhibited a sensitivity and limit of detection (LOD) of 0.469 nm/ln(μg/mL) and 0.142 μg/mL in the linear detection range of 0.5–50 μg/mL. The fiber optic tip-based sensor exhibited a sensitivity and LOD of 1.16 nm/ln(μg/mL) and 0.176 μg/mL within the 1–50 μg/mL linear detection range. The obtained sensing results reveal that the sensors presented in this study are able to accurately detect nitrite at various concentrations in a quantitative manner. Moreover, an assessment was conducted to examine the selectivity and reusability of the sensor individually, yielding satisfactory results.

As the most economically developed area in China, the environmental water quality of Guangdong-Hong Kong-Macao Greater Bay Area has received extensive attention, and the spatial variations of total phosphorus (TP) in the Greater Bay were significant, conventional laboratory analysis is difficult to meet the requirements of TP monitoring due to time and cost consuming, and Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) technology, combined with the self-adaptive partial least squares (SA-PLS) model, was used to determine the TP concentration. The results showed that P-O vibrations were observed in the wavenumber range of 1200–900 cm−1, and prediction models were established by using this range. For the conventional partial least squares (PLS) model, the R2, RMSE and RPD were 0.817, 0.022 mg L−1 and 2.335, respectively, while for the SA-PLS model the prediction was improved with the values of 0.965, 0.010 mg L−1, 5.296, respectively, and the SA-PLS mode prediction was satisfied when the TP content in water was more than 0.05 mg L−1. It was found that the TP determination was interfered by sulfate, when the sulfate content was < 100 mg L−1, both SA-PLS and the conventional PLS model could be used for quantitative analysis of TP; when sulfate content was > 100 mg L−1, PLS model could not be used while the SA-PLS model still achieved an excellent prediction. Therefore, FTIR-ATR combined with SA-PLS model can rapidly determine TP in water, providing an alternative strategy for monitoring TP in natural water bodies.

Hepatitis C virus infection constitutes a significant global public health concern. Fluorescence technique (FL) is a promising biosensor, however, many conventional dyes exhibit reduced fluorescence or no emission at high concentrations. To break through this shackle, an ultrasensitive AIE-based (aggregation-induced emission) FL sensing platform was developed for HCV detection by using the FLRNAs-based T7 isothermal transcription amplification RNA diagnosis combined with AIE luminogens (FTAR) strategy. In the FTAR strategy, the T7 transcription amplification process was responsible for the recognition of the target HCV and produced Pepper aptamer, which could form aggregates of nanoparticles with the HBC, an AIEgen, to produce high-intensity FL. The multi-integrated signal amplification strategy led to ultrasensitivity. Moreover, under the optimal experimental conditions, HCV could be assayed in the range of 100aM-100pM. The proposed strategy has been successfully applied in detecting HCV in clinical samples. In summary, this research was the first to utilize aptamer restriction of AIEgens internal rotation to achieve aggregation-induced emission and presented the successful development of a specific, sensitive and rapid FTAR assay for HCV diagnosis. The proposed FTAR platform with facile operation, short analysis time, low-cost as well as excellent quantification ability could provide a promising tool for point-of-care testing (POCT).

In the development of biosensors, it is essential to have sensors that provide rapid responses, exhibit high sensitivity and selectivity, and are non-invasive, such as screen-printed carbon electrode-based biosensors. In this study, SPCE-based and fabric-based biosensors were fabricated by modifying the working electrode (WE) surface using functionalized Multi-walled Carbon Nanotube/AgNi nanocomposites (f-MWCNT/AgNi) to enhance the biosensor's performance in detecting uric acid (UA). The successful synthesis of the f-MWCNT/AgNi nanomaterial was confirmed through UV–Vis, Raman, SEM–EDX, and XRD analyses. The f-MWCNT/AgNi nanomaterials were deposited on the WE surface using drop-casting. Subsequently, electrochemical characteristic tests and UA detection performance were conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The DPV curves revealed sensitivities of 27.699 μA/mM and 4.638 μA/mM for SPCE-based and fabric-based electrodes, respectively. The limit of detection (LOD) values for UA detection were 0.024 and 0.017 mM, with linearity (R2) 0.997 and 0.999 observed within the linear ranges of 0.05–1.00 and 1.0–5.0 mM, respectively. Both biosensors exhibited strong selectivity for UA against other components, including ascorbic acid, glucose, lactic acid, and ethanol. Based on these parameter values, f-MWCNT/AgNi-modified SPCE and fabric-based electrodes can be promoted as biosensors for uric acid detection.

In this paper, we report, for the first time to our knowledge, a new versatile and future proof diagnostic platform for diverse applications and heterogeneous biological targets. This platform relies on a plasmonic-augmented silicon photonic biochip to detect bacteria and protein biomarkers within minutes. To demonstrate the potential of this platform in diverse applications, we demonstrate the detection of two heterogeneous targets, the bacterium Escherichia coli (E. coli) and the molecule C-reactive protein (CRP) using a universal detection method. E. coli is one of the most commonly encountered bacterial pathogens involved in food monitoring, food born infections and water contamination applications, while CRP is a well-established disease severity indicator frequently used in common clinical practice. The biochip used is fully compatible with CMOS semiconductor manufacturing, while it hosts biosensors arrays for any combination of detection assays. Each biosensor exploits a 70 μm long aluminum plasmonic transducer within a silicon nitride waveguide-based Mach–Zehnder Interferometer. Each aluminum surface was silanized and biomodified with specific antibodies. Biosensing experiments revealed that CRP can be detected in diverse sample mediums, and E. coli detection was achieved in buffer at concentrations as low as 10 cells/ml within 13–25 min. The results are in good agreement with preceding numerical simulations. The modular nature of the reported biosensing platform makes it scalable and customizable, allowing nearly any combination of diagnostic tests targeting pathogens and proteins to be integrated on the same biochip for food quality monitoring, environmental monitoring, drug discovery and modern cell therapy manufacturing, or biomedical applications.

Exhausting carbon-based gases from building construction or comfortable household supplies have caused the main pollution gas species for the indoor air environment. Given the variety of indoor activities, many reports have been challenged to find room-temperature operational and harmless materials. Here, we report that the activating MoO vibration mode in Na,Sb doped-NiMoO4 micro-sized powder reveals the high response of CO and VOC, occupying multiple bonds at room temperature. We performed Na and Sb doping in the α-NiMoO4 crystal structure, such as introducing the Sb in Ni and interstitial doping of Na in around 4 Å of free space in the NiMoO4 crystal structure that manipulates the partial β-NiMoO4 phase. The Na,Sb-codoped NiMoO4 generates the higher MoO vibration mode from FT-IR measurement and enables carbon-based gas detection with 38 responses to CO and nearly 20 responses to VOC under 20 ppm of each analyte gases environment. Furthermore, the n-type gas sensing behavior of Na,Sb doped-NiMoO4 chemiresistor exhibits an immediate sensing response instead of a none-of response than intrinsic or single element doped NiMoO4. These results suggest that Na,Sb codoped-NiMoO4 is the applicable material for emergent warning against carbon-based gas exposure in the indoor environment. In addition, activating the electrochemical reaction site of MoO4–2 in NiMoO4 is tailorable by a simple doping process.

High temporal and spatial resolution electrochemical sensor arrays can greatly benefit various parallel sensing applications. Herein, we provide a simple method for the controlled and scaled fabrication of bipolar nanoelectrode arrays (BPnEAs) for high-resolution electrochemical sensing applications. BPnEAs are prepared on silicon nitride film windows through the dual-beam FIB nanofabrication technique. Coupling a conventional electrochemical redox reaction with a tris (2,20-bipyridyl) ruthenium /2-(dibutylamino)ethanol electrochemiluminescence (ECL) system, which is based on a high-viscosity solvent to reduce molecular diffusion, allows for the reporting of conventional electrochemical redox processes with high spatial and temporal resolution. The use of the BPnEA-ECL sensor is demonstrated on 10 × 10 Pt or C BPnEAs for monitoring the reduction of 0.5 M H2SO4. BPnEA-ECL sensors containing different electrode materials (Pt and C) are reported for the first time and are used to monitor the reduction of 0.5 M H2SO4, thus revealing the difference in electrocatalytic capacities between Pt and C. Subsequently, we reveal the outstanding capabilities of the BPnEA-ECL system for catalyst screening.

Hydrogen peroxide (H2O2) sensing has been widely investigated using various electrochemical methods, yet the challenge of finding an imaging technique capable of real-time, spatially resolved detection remains. Addressing this, we introduce a Prussian blue (PB) nanofilm-sensitized plasmonic electrochemical microscopy (PEM) technique that successfully visualizes the localized delivery of H2O2. The PB nanofilm was carefully characterized, and its sensing capability towards H2O2 was demonstrated in amperometric mode. Employing a precise micromanipulator system, we controlled a micropipette to create a localized concentration gradient on the sensor surface and monitored the gradient through the PB nanofilm-sensitized PEM. The accuracy of the obtained concentration values was further validated by numerical simulations based on finite-element methods. Our technique ensures dependable localized detection, and we anticipate that advancements in film uniformity will further improve the resolution. The potential applications of this technique are broad and significant, including the opportunity to investigate single-cell exocytosis with neurotransmitters like dopamine, thus offering a promising avenue for future biomedical research.

Electrochemical impedance spectroscopy (EIS) is a reliable technique for gathering information about electrochemical process occurring at the electrode surface and investigating properties of materials. Furthermore, EIS technique can be a very versatile and valuable tool in analytical assays for detection and quantification of several chemically and biologically relevant (bio)molecules. The first part of this Review (Introduction) provides brief insights into (i) theoretical aspects of EIS, (ii) the instrumentation required to perform the EIS studies and (iii) the most relevant representations of impedance experimental data (such as Nyquist and Bode plots). In the end of this section, (iv) theoretical aspects regarding the fitting of the Randles circuit to experimental data are addressed, not only to obtain information about electrochemical processes but also to illustrate its utility for analytical purposes. The second part of the Review (Impedimetric Detection of Disease Biomarkers) focuses on the applications of EIS in the biomedical field, particularly as analytical technique in electrochemical sensors and biosensors for screening disease biomarkers. In the last section (Conclusions and Perspectives), we discuss main achievements of EIS technique in analytical assays and provide some perspectives, challenges and future applications in the biomedical field.

Multi-channel neural electrodes as a crucial means are of great significance for information exchange between the brain and computers. Herein, we present a 16-channel Si-based active neural probe system that achieves a monolithic integration between the electrodes and circuits in a single probe, making it a standalone integrated electrophysiology recording system. The ASIC prepared on a base (2×2mm2) is a 16-channel analog frontend (AFE) for neural recording, and each channel has a low-noise amplifier (LNA), a bandpass filter (BPF), a buffer and a current bias circuit. The 258 neural signal recording electrodes (22×24μm2) are densely packed on a 50 μm thick, 100 μm wide, and 3 mm long shank. The ASIC of neural probe, internal interconnecting wires are all implemented in commercial SMIC 0.18 μm CMOS technology. The neural probe system achieves a 3.6 μVrms input-referred noise (IRN) in a bandwidth of 1.1Hz-10 kHz, 70.8 μW power consumption, 0.0785 mm2 area per channel, as well as an AFE gain of 58.1 dB Furthermore, the impedances of the Au electrodes can be obtained as 0.5–2.1 MΩ at a frequency of 1 kHz. The functionality of a 16-channel silicon-based neural probe is validated in an in-vivo experiment on lab rats.

For the 29.8 million people in the world living with HIV/AIDS and receiving antiretroviral therapy, it is crucial to monitor their HIV viral loads. To this end, rapid and portable diagnostic tools that can quantify HIV RNA are critically needed. We report herein a rapid and quantitative digital CRISPR-assisted HIV RNA detection assay that has been implemented within a portable smartphone-based device as a potential solution. Specifically, we first developed a fluorescence-based reverse transcription recombinase polymerase amplification (RT-RPA)-CRISPR assay that can efficiently detect HIV RNA at 42 °C. We then implemented this assay within a commercial stamp-sized digital chip, where RNA molecules were quantified as strongly fluorescent digital reaction wells. The isothermal reaction condition and the strong fluorescence in the digital chip simplified the design of thermal and optical modules, allowing us to engineer a palm-size device measuring 70 × 115 × 80 mm and weighing less than 0.6 kg. We also capitalized the smartphone by developing a custom app to control the device, perform the digital assay, and capture fluorescence images throughout the assay using the smartphone's camera. Moreover, we trained and verified a deep learning-based algorithm for analyzing fluorescence images and identifying positive digital reaction wells with high accuracy. Using our smartphone-enabled digital CRISPR device, we successfully detected as low as 75 copies of HIV RNA in just 15 min, showing its potential toward monitoring of HIV viral loads and aiding the global effort to combat the HIV/AIDS epidemic.

To practically utilized the organometallic lead halide perovskites to optoelectronic devices and photoelectrochemical cells, numerous efforts have been utilized to obtain the perovskites with low-energy process with coverage of various inorganic mediums to improve stability against humidity. By utilizing ligand-assisted reprecipitation process, under ambient condition at room temperature, the dimensionally confined perovskite quantum dots in silica matrices (PQD@SiOx) were obtained, and they were stable under several months under the ambient condition. To apply the PQD@SiOx to the photoelectrochemical cells by introducing direct contact between PQD@SiOx and electrolyte, the material/photophysical properties under electrochemical conditions are necessary to be studied. However, the role of silica coverage to the electrochemical behaviors of the PQD cores in the silica medium were not yet studied. In this work, under the electrochemical conditions, the oxidative and reductive behaviors of the PQD@SiOx were studied. Also, through in-situ spectroelectrochemical study, the electrochemically induced irreversible deformation process were tracked. The findings of this study could be used to understand role of silica coverage and develop the strategy to improve the protecting behavior of the silica for the PQD cores to utilize into the photoelectrochemical cells.