Extended Detection Range Research Articles

Marine remote target signal extraction based on 128 line-array single photon LiDAR

LiDAR technology has garnered significant attention in recent years due to its superior directivity, high resolution, and precise 3D information acquisition capabilities, making it indispensable in navigation systems. Among its variants, single-photon LiDAR stands out for maritime applications, owing to its reduced power consumption and extended detection range. However, the high sensitivity of single-photon detectors often results in substantial noise, necessitating effective denoising before data can be utilized for identification, tracking, and other purposes. In this study, we present a novel 128-line, 1550 nm shipborne long-range single-photon LiDAR system, with data collected and analyzed in maritime environments. This system contends with challenges such as a large dynamic range, abundant noise photons, and the complexity of sea surface conditions. To address these issues, we propose an efficient and adaptive denoising algorithm based on the k-th nearest neighbor (KNN) methodology. By examining the distribution characteristics of signal and noise photons, our approach enables target extraction even under conditions of intense noise and sparse signals. Our method exhibits robust adaptability across various detection scenarios. Experimental evaluations demonstrate its efficacy, accurately identifying targets at distances of 3.2 km in clear weather and 1.6 km in foggy conditions.

Advancing polarity-transcendent design: Development of a photoelectrochemical sensor with extended detection range

In photoelectrochemical (PEC) sensors, traditional detection modes such as "signal-on", "signal-off", and "polarity-switchable" limit target signals to a single polarity range, necessitating novel design strategies to enhance the operational scope. To overcome this limitation, we propose, for the first time, a "polarity-transcendent" design concept that enables a continuous response across the polarity spectrum, significantly broadening the sensor's concentration detection range. This concept is exemplified in our new "background-enhanced signal-off polarity-switchable" (BESOPS) mode, where the model analyte let-7a activates a cascade shearing reaction of a DNAzyme walker in conjunction with CRISPR/Cas12a, quantitatively peeling off Cu2O-H2 strands at the Cu2O/TiO2 electrode interface to expose the TiO2 surface. This exposure generates an anodic photocurrent at the expense of the cathodic photocurrent from Cu2O/TiO2, facilitating a seamless transition of the target signal from cathodic to anodic. Through systematic experiments and comparative analyses, the BESOPS sensor demonstrates highly sensitive and precise quantification of let-7a, with a detection limit of 2.5 aM and a broad operating range of 10 aM to 10 nM. Its performance exceeds most reported sensor platforms, highlighting the significant potential of our polarity-transcendent design in expanding the operational range of PEC sensors. This innovative approach paves the way for developing next-generation PEC sensors with enhanced applicability and heightened sensitivity in various critical fields.

Light-Cured Junction Formation and Broad-Band Imaging Application in Thermally Mismatched van der Waals Heterointerface.

Van der Waals (vdW) heterostructures are mainly fabricated by a classic dry transfer procedure, but the interface quality is often subject to the vdW gap, residual strains, and defect species. The realization of interface fusion and repair holds significant implications for the modulation of multiple photoelectric conversion processes. In this work, we propose a thermally mismatched strategy to trigger broad-band and high-speed photodetection performance based on a type-I heterostructure composed of black phosphorus (BP) and FePS3 (FPS) nanoflakes. The BP acts as photothermal source to promote interface fusion when large optical power is adopted. The regulation of optical power enables the device from pyroelectric (PE) and/or alternating current photovoltaic (AC-PV) mode to a mixed photovoltaic (PV)/photothermoelectric (PTE)/PE mode. The fused heterostructure device presents an extended detection range (405~980 nm) for the FPS. The maximum responsivity and detectivity are 329.86 mA/W and 6.95 × 1010 Jones, respectively, and the corresponding external quantum efficiency (EQE) approaches ~100%. Thanks to these thermally-related photoelectric conversion mechanism, the response and decay time constants of device are as fast as 290 μs and 265 μs, respectively, superior to current all FPS-based photodetectors. The robust environmental durability also renders itself as a high-speed and broad-band imaging sensor.

Flexible dual-mode pressure sensor for simultaneous dynamic-static sensing with wide-range detection and ultra-fast response speed

Flexible pressure sensors play a vital role in advancing the Internet of Things (IoT). However, piezoelectric sensors are limited in static pressure detection and suffer in achieving high flexibility and high sensitivity simultaneously, while piezoresistive sensors typically have slow response speeds and insensitive high-frequency detection ability. Here, we select a novel basalt fiber fabric (BFF) that can withstand high temperatures exceeding 1000 °C as a new substrate to enable one-step fabrication of piezoelectric layer based on coherently grown Pb(Zr0.52Ti0.48)O3 (PZT) thin films via a simple dipping method. The high piezoelectric coefficient g33 of 362.5 mV·m·N−1 and the unique core-sheath structure induced stress concentration on the PZT sheath enable the flexible piezoelectric layer (bending radius < 1.45 mm) to exhibit high sensitivity (voltage sensitivity of 2.766 V/kPa within the range of 0.11–11.11 kPa) and fast response speed (11 ms). The piezoresistive layer consisting of a three-dimensional porous elastic carbon nanotube-polyurethane sponge provides a detection range comparable to piezoelectric layer (0.11–66.67 kPa). A dual-mode flexible pressure sensor (DMFS) has been developed by integrating the piezoelectric layer with the piezoresistive layer. The DMFS exhibits an extended detection range compared to previous dual-mode pressure sensors, rapid response speed, and high sensitivity, which enables simultaneous detection of both dynamic and static pressures. The DMFS can be used for keyboard and movement posture recognition, which has significant application prospects in human-machine interaction.

Development of a near-infrared single-photon 3D imaging LiDAR based on 64×64 InGaAs/InP array detector and Risley-prism scanner.

A near-infrared single-photon lidar system, equipped with a 64×64 resolution array and a Risley prism scanner, has been engineered for daytime long-range and high-resolution 3D imaging. The system's detector, leveraging Geiger-mode InGaAs/InP avalanche photodiode technology, attains a single-photon detection efficiency of over 15% at the lidar's 1064 nm wavelength. This efficiency, in tandem with a narrow pulsed laser that boasts a single-pulse energy of 0.5 mJ, facilitates 3D imaging capabilities for distances reaching approximately 6 kilometers. The Risley scanner, composing two counter-rotating wedge prisms, is designed to perform scanning measurements across a 6-degree circular field-of-view. Precision calibration of the scanning angle and the beam's absolute direction was achieved using a precision dual-axis turntable and a collimator, culminating in 3D imaging with an exceptional scanning resolution of 28 arcseconds. Additionally, this work has developed a novel spatial domain local statistical filtering framework, specifically designed to separate daytime background noise photons from the signal photons, enhancing the system's imaging efficacy in varied lighting conditions. This paper showcases the advantages of array-based single-photon lidar image-side scanning technology in simultaneously achieving high resolution, a wide field-of-view, and extended detection range.

A double methylene blue labeled single-stranded DNA and hairpin DNA coupling biosensor for the detection of Fusarium oxysporum f. sp. cubense race 4

The DCL gene in Fusarium oxysporum f. sp. cubense Race 4 (Foc4) is a pivotal pathogenic factor causing banana fusarium wilt. Precise DCL detection is crucial for Foc4 containment. Here, we present a novel ssDNA-hDNA coupling electrochemical biosensor for highly specific DCL detection. The sensing interface was formed via electrodeposition of a composite containing reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) onto a carbon screen-printed electrode (SPE), followed by thiol-modified ssDNA functionalization. Additionally, the incorporation of hDNA, with methylene blue (MB) at both ends, binds to ssDNA through base complementarity, forming an ssDNA-hDNA coupling probe with bismethylene blue. This sensing strategy relies on DCL recognition by the hDNA probe, leading to DNA hairpin unfolding and detachment of hDNA bearing two MBs from ssDNA, generating a robust “on-off” signal. Empirical results demonstrate the sensor's amplified electrical signals, reduced background currents, and an extended detection range (6.02 × 106–3.01 × 1010 copies/μL) with a limit of detection (3.01 × 106 copies/μL) for DCL identification. We applied this sensor to analyze soil, banana leaves, and fruit samples, confirming its high specificity and stability. Moreover, post-sample detection, the sensor exhibits reusability, offering a cost-effective and rapid approach for banana wilt detection.

Photonic integrated circuit with multiple waveguide layers for broadband high-efficient 3D OPA.

The traditional photonic integrated circuit (PIC) inherits the mature CMOS fabrication process from the electronic integrated circuit (IC) industry. However, this process also limits the PIC structure to a single-waveguide-layer configuration. In this work, we explore the possibility of the multi-waveguide-layer PIC by proposing and demonstrating a 3D optical phased array (OPA) device, with the light exiting from the edge of the device, based on multi-layer Si3N4/SiO2 stacks. This device is in a multi-waveguide-layer configuration at every single position of the device. This configuration offers the possibility of using edge couplers at both the input and the emitting ends to achieve broadband high efficiency, and its uniqueness provides the potential for a more extended detection range in the lidar application. The device has been studied by numerical simulation, and proof-of-concept samples have been fabricated and tested.

A Time-Division Multifrequency Wind Lidar With High Spatial Resolution and Extended Detection Range

Limited by the achievable pulse peak power, narrowing the transmitted pulsewidth to improve the spatial resolution would reduce the output power of wind Lidar, thereby decreasing the detection range. To solve this dilemma, a time-division multifrequency wind Lidar (TDMWL) is proposed with a long pulse duration consisting of consecutive multiple subpulses at different frequencies. Different detection ranges can be separated by different downconverted frequencies. The accumulation of multifrequency spectra enlarges the output power, while the width of the subpulse determines the spatial resolution. In the experiment, with a subpulse width of 200 ns, the detection range is increased from 750 to above 1200 m by accumulating six frequencies, proving the potential of TDMWL in measuring longer range without deteriorating the spatial resolution.

Electrochemical sensing of Staphylococcus aureus based on conductive anti-fouling interface.

Asystem for the rapid and ultra-sensitive detection of Staphylococcus aureus (S. aureus), a prevalent foodborne pathogenis introduced. Limitations of typical electrochemical sensing, often subjected to interference from non-specific protein adsorptionare addressed. Adual-aptamer-based sandwich immunobiosensor is shown for its benefits regardingspecificity and anti-fouling capacity, endowed by a sulfonated polyaniline layer combined with signal amplification via highly conductive gold nanoparticles. EIS spectra (Nyquist plots) were recorded at pH 7.4 PBS containing 5mM Fe(CN)63-/Fe(CN)64-, in order to verify the possibility of the electrochemical sensing for detection of S. aureus. Results demonstrated that the constructed immunobiosensor presents an extended detection range (1 × 101 to 1 × 105CFU/mL) and detection limit as low as 2CFU/mL. The resistance values of the immunobiosensor developed maintain at a stable value during 2weeks. Besides, the specificity of the system is highlighted by testing raw milk, and the results of which demonstrate the excellent prospects of the system for monitoring foodborne pathogens.

Secured Perimeter with Electromagnetic Detection and Tracking with Drone Embedded and Static Cameras

Perimeter detection systems detect intruders penetrating protected areas, but modern solutions require the combination of smart detectors, information networks and controlling software to reduce false alarms and extend detection range. The current solutions available to secure a perimeter (infrared and motion sensors, fiber optics, cameras, radar, among others) have several problems, such as sensitivity to weather conditions or the high failure alarm rate that forces the need for human supervision. The system exposed in this paper overcomes these problems by combining a perimeter security system based on CEMF (control of electromagnetic fields) sensing technology, a set of video cameras that remain powered off except when an event has been detected. An autonomous drone is also informed where the event has been initially detected. Then, it flies through computer vision to follow the intruder for as long as they remain within the perimeter. This paper covers a detailed view of how all three components cooperate in harmony to protect a perimeter effectively, without having to worry about false alarms, blinding due to weather conditions, clearance areas, or privacy issues. The system also provides extra information of where the intruder is or has been, at all times, no matter whether they have become mixed up with more people or not during the attack.

Mixed-phase β-Ga2O3 and SnO2 metal-semiconductor-metal photodetectors with extended detection range from 293 nm to 330 nm

In this article, we demonstrate β-Ga2O3 and SnO2 mixed-phase thin films with dominant (2¯01)-β-Ga2O3 and (200)-SnO2 orientations on c-face sapphire (c-Al2O3) by chemical vapor deposition in a tube furnace. Transmission electron microscopy (TEM) reveals their simultaneous growth on substrate due to the small mismatches of (2¯01)-β-Ga2O3/c-Al2O3 (∼3%) and (200)-SnO2/c-Al2O3 (∼0.6%). Therefore, we also successfully demonstrate preferred-orientation (2¯01)-β-Ga2O3 and (200)-SnO2 mixed-phase thin films by controlling the Sn and Ga ratios in precursors. At 40 V, the photoelectric properties of metal-semiconductor-metal (MSM) photodetectors are modulated with more SnO2 content in mixed-phase thin films, including the dark current from 11 pA to 4 nA, the peak response in UVC from 240 nm (2 mA/W) to 260 nm (1.15 A/W), the tunable cut-off wavelength from 274 nm to 297 nm, and the extended detection range at long wavelength from 293 nm to 330 nm. Our devices show Ga2O3-like photoresponse properties rather than SnO2-like properties with lower dark current, comparable responsivity and detectivity, and faster response time than the performances of parts of the pure and mixed-phase Ga2O3-based photodetectors with untunable detection rang, which is expected to extend wider applications of other Ga2O3-based mixed-phase materials during doping or alloying, and paves a new and feasible way to realize high-performance Ga2O3-based photodetectors with controllable detection range.

Deep-Depletion Effect in SOI Substrates and its Application in Photodetectors With Tunable Responsivity and Detection Range

We present an interesting transient effect found in silicon-on-insulator (SOI) transistors, where the drain current responds slowly to a back-gate voltage ( ${V}_{\text {BG}}$ ) pulse. This transient mechanism is due to the deep-depletion region in the SOI substrate induced by the ${V}_{\text {BG}}$ pulse and has been validated by experimental and TCAD simulation results. The deep-depletion characteristic can be employed for photodetection in a fully depleted (FD)-SOI MOSFET device. We have measured the photoresponse of the FD-SOI MOSFET under various light illumination conditions and studied systematically the impact of the ${V}_{\text {BG}}$ pulse duty ratio, amplitude, and period on the responsivity and detection range. An optimized device structure, fabricated in an advanced ultrathin body and buried oxide (BOX) (UTBB) SOI technology, shows low operation voltage and extended detection range.

Magnetic characteristics of a magnetic marker for localized tumor excision with a handheld magnetic probe

To excise the non-palpable breast lesion, conventionally surgeons estimate the excision margin by naked eyes subjectively with a localization tool such as a hook wire. By introducing a magnetic detection system, location of the magnetic marker injected intratumorally can be identified with a handheld magnetic probe. Detection ranges of existing magnetic markers are up to 30 mm, limiting applications on tumors located deeper down the skin. In this study, materials and designs of magnetic markers are evaluated to achieve an extended detection range. Stainless steel (SUS) 304 is magnetic and biocompatible for an implant device, and a SQUID measurement is performed to evaluate its magnetic properties. A numerical simulation tool has been developed to evaluate the magnetic field strength induced by the magnetic marker from any orientation. Based on a backward-facing hook shape design, magnetic field strength induced by the marker with varies hook length and separation angle between the hook and the main body is evaluated. At an extended distance of 40 mm, the detection of the magnetic marker with 8 mm hook length and 75° separation angle can be achieved on 57% of the orientations.

Remarkably enhanced H2 response and detection range in Nb doped rutile/anatase heterophase junction TiO2 thin film hydrogen sensors

Hydrogen sensors combining wide detection range and high response, that can operate at room temperature, are urgently demanded for monitoring different concentrations of hydrogen on a single device. Here, a novel one-step hydrothermal method is reported to construct Nb doped rutile/anatase TiO2 heterophase junctions for a highly sensitive H2 sensor. The Nb concentration in the solvent plays an important role for the heterophase juncton self-assemble, and the reaction time determines the surface morphology giving either a rutile TiO2 nanorod decorated anatase form, or a Nb doped rutile/anatase TiO2 bi-layer structure. An inverse dependence of the detectivity on H2 concentration is obtained as theoretically predicted but previously not experimentally verified for the high concentration region at low temperatures. The H2 concentration detection range is remarkably expanded, extending from 1 ppm to 12000 ppm for nanorod decorated film. The H2 response at 1 ppm is significantly enhanced to 22.5%, and reaches 98.9% in 8000 ppm H2 for the bilayer structure. The remarkablely extended detection range is the result of the massive accumulation of reactive pre-absorbed O2− on the surface due to the Nb doping, and the significantly enhanced response at room temperature results from the joint contributions of pre-absorbed O2−, film compactness and the heterophase junction. Moreover, Nb doped rutile/anatase TiO2 heterophase juncton films show high stability and humidity resistance for hydrogen sensing.

Three-dimensional microfluidic paper-based device for multiplexed colorimetric detection of six metal ions combined with use of a smartphone.

A simple double-layered three-dimensional (3D) microfluidic paper-based analytical device (μPAD) was designed for the simultaneous determination of six metal ions-Fe(III), Ni(II), Cr(VI), Cu(II), Al(III), and Zn(II)-for the first time. The 3D μPAD was composed of two paper layers: a top pretreatment layer and a bottom colorimetric detection layer. The sample solution added to the central sample reservoir of the 3D μPAD could be automatically divided into eight flow pathways and be automatically pretreated while flowing through the pretreatment zones located in the microfluidic channels, and automatically carried out the chromogenic reactions after reaching the detection zones. Random diffusion of the chromogenic reagents was effectively prevented by transport of the pretreated sample solution to the detection zones through 3D microfluidic channels with an L-type circuitous flow route design, resulting in highly increased color uniformity and reproducibility. Combined with use of a flat LED lamp as an upward lighting source and a smartphone as a convenient detector, improved color perception, highly enhanced sensitivity, and an extended detection range were obtained. Finally, the double-layered 3D μPAD was applied to the multiplexed determination of the six metal ions in mixtures and environmental samples with satisfactory results. Detection limits as low as 0.2, 0.3, 0.1, 0.03, 0.08, and 0.04 mg/L for Fe(III), Ni(II), Cr(VI), Cu(II), Al(III), and Zn(II) detection, respectively, were achieved, which are about one order of magnitude lower than obtained with previously reported μPADs for the detection of metal ions. The present 3D μPAD is simple, fast, selective, sensitive, and user-friendly, and holds great application potential for multiplexed on-site analysis.

Rapid spectroscopic determination of silver in Ag-loaded cellulosic materials

A new procedure for the determination of silver (Ag) in Ag-loaded cellulosic materials is proposed that is based on a spectroscopic method. Two calibration models were established based on ultraviolet–visible (UV–vis) spectroscopy (Model 1) and ratio spectrum-derivative spectrophotometry (Model 2). The correlation coefficient of Model 1 is 0.9852 when the concentration of silver ions (Ag+) in AgCl suspension system is < 1.0 mmol/l. By contrast, Model 2 exhibits an extended detection range, from 0 to 1.2 mmol/l, and its correlation coefficient was as large as 0.9941. The standard deviation of 0.8080 for Model 2 is substantially lower than that of Model 1 (1.0744), which explains why better reproducibility was achieved by the former. Validation experiments show the average relative errors for two models, 5.15% (Model 1) and 2.35% (Model 2), respectively, which indicates that predictability of Model 2 is better than that of Model 1. Compared with traditional methods, the proposed test procedures were simpler, human errors were reduced, and testing time was shortened. The new method has high precision and accuracy and is satisfactorily applied for the determination of silver in Ag-loaded cellulosic materials.

Noise reduction in Lidar signal using correlation-based EMD combined with soft thresholding and roughness penalty

Empirical mode decomposition (EMD) is widely used to analyze the non-linear and non-stationary signals for noise reduction. In this study, a novel EMD-based denoising method, referred to as EMD with soft thresholding and roughness penalty (EMD-STRP), is proposed for the Lidar signal denoising. With the proposed method, the relevant and irrelevant intrinsic mode functions are first distinguished via a correlation coefficient. Then, the soft thresholding technique is applied to the irrelevant modes, and the roughness penalty technique is applied to the relevant modes to extract as much information as possible. The effectiveness of the proposed method was evaluated using three typical signals contaminated by white Gaussian noise. The denoising performance was then compared to the denoising capabilities of other techniques, such as correlation-based EMD partial reconstruction, correlation-based EMD hard thresholding, and wavelet transform. The use of EMD-STRP on the measured Lidar signal resulted in the noise being efficiently suppressed, with an improved signal to noise ratio of 22.25 dB and an extended detection range of 11 km.

Hollow fiber sensor based on metal-cladding waveguide with extended detection range.

A new hollow fiber sensor based on metal-cladding waveguide configuration for the detection of the refractive index of liquid is proposed and demonstrated. Due to the existence of both surface and guided modes in the metal-insulator-metal waveguide, the proposed sensor can detect liquid with refractive index either higher or lower than the insulator layer, which significantly extends the detection range. The characteristics of metal-cladding waveguide is analyzed and presented, while the performance of the sensor is numerically calculated and evaluated. The results evince that, the designed fiber sensor can effectively detect both high and low refractive index liquid by respectively exciting surface mode and guided mode.

OFDM Based Radcom System With Improved Performance Using Digital Beamforming Technique

In recent past the influence of Radar has played a significant part in various fields. Radar sensing is one of the prime application by which velocity and distance of a moving target can be found out. A joint RadCom system to serve both radar sensing and wireless communication is proposed which ensures better performance in terms of spectral efficiency, extended detection range and cost effectiveness. Such systems demand for a common waveform which is designed in this work that perfectly matches to the system requirements. OFDM multi carrier technique is chosen to generate a common waveform. Applicability of multiple antenna technique for direction of arrival estimation is also considered. MIMO-OFDM technique has gained much interest in the field of communication which improves the signal to noise ratio and lowers the bit error rate. On the other hand the usage of MIMO reflects in the form of interference between signals. In order to overcome this effect beamforming technique is used. In addition to theoretical explanations we have also simulated and discussed the results for the proposed RadCom system using MATLAB simulation tool.

Two-Channel Metal Detector Using Two Perpendicular Antennas

Two-channel metal detector, having two sets of perpendicularly oriented sensor antennas, is proposed to expand detectable size, ranging from mm through cm scale, of metal sensor, while conventional metal sensor is dedicated for detection only in mm or cm scale. The characteristics of the two metal detection sensor channels were investigated, respectively, and the interference effect, while in simultaneous operation, between two sensor channels was discussed. Metal detection channel, having sensitivity in mm scale, showed detectable sensitivity to moving ferrous sphere, with diameter down to 0.7 mm, at 50 kHz exciting frequency and enhanced sensitivity distribution. And metal detection channel having sensitivity in cm scale showed more uniform sensitivity distribution with the flexibility for future modular construction. The effect of interference, while in simultaneous operation of two sensors, resulted in reduced output response, but still within usable detection range. Thus it was feasible to operate two sensors, having different sensitivity range, simultaneously and to extend detection range from mm to cm scale, within practically acceptable interference.