Dynamic Range Research Articles

Ultrasensitive dim-light neuromorphic vision sensing via momentum-conserved reconfigurable van der Waals heterostructure

Reconfigurable phototransistors featuring bipolar photoresponses are favorable for manipulating high-performance neuromorphic vision sensory. Here, we present a momentum-conserved reconfigurable phototransistor based on the van der Waals heterojunction between methylammonium lead iodide perovskite and two-dimensional Bi2O2Se semiconductor, which exhibits a synergistic interplay of interband hot-carrier transitions and reconfigurable heterointerface band alignments, eventually achieving the ultrahigh bipolar optoelectronic performances with the photoresponsivity of 6×107 AW−1, accompanied by the specific detectivity of 5.2×1011 Jones, and the dynamic range of 110 dB. Moreover, A 3×3 heterotransistor array is fabricated to perform in-sensor analog multiply-accumulate operations even under the challenging dim illumination of 0.1 μWcm−2 that comparable to natural moonlight. The reconfigurable heterotransistor array can be further adopted to enhance the traffic-light detection under dim-light conditions. Our advancement in momentum-conserved reconfigurable heterotransistor signifies a leap forward in real-time, energy-efficient, and low-light image processing for neuromorphic vision sensors.

Optimization Strategies for Rydberg Atom-based AM Receiver Operational Parameters

Abstract The Rydberg atom-based receiver, as a novel type of antenna, demonstrates broad application prospects in the field of microwave communications. However, since Rydberg atomic receivers are nonlinear systems, mismatches between the parameters of the received amplitude modulation (AM) signals and the system's linear workspace and demodulation operating points can cause severe distortion in the demodulated signals. To address this, the article proposes a method for determining the operational parameters based on the mean square error (MSE) and total harmonic distortion (THD) assessments, and presents strategies for optimizing the system’s operational parameters focusing on linear response characteristics (LRC) and linear dynamic range (LDR). Specifically, we employ a method that minimizes the MSE to define the system’s linear workspace, thereby ensuring the system has a good LRC while maximizing the LDR. To ensure the signal always operates within the linear workspace, an appropriate carrier amplitude is set as the demodulation operating point. By calculating the THD at different operating points, the LRC performance within different regions of the linear workspace is evaluated, and corresponding optimization strategies based on the range of signal strengths are proposed. Moreover, to more accurately restore the baseband signal, we establish a mapping relationship between the carrier Rabi frequency and the transmitted power of the probe light, and optimize the slope of the linear demodulation function to reduce the MSE to less than 0.8×10-4. Finally, based on these methods for determining operational parameters, we explore the effects of different laser Rabi frequencies on system performance, and provide optimization recommendations. This research provides robust support for the design of high-performance Rydberg atom-based AM receivers.

A comparison of branched DNA and reverse transcriptase quantitative polymerase chain reaction methodologies for quantitation of lipid nanoparticle encapsulated mRNA.

Messenger RNA (mRNA)-based therapeutics have emerged as a promising modality for various clinical applications, necessitating robust methods for mRNA quantification. This biodistribution study compares the performance of branched DNA and reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) assays for measuring lipid nanoparticle-encapsulated mRNA. Following intravenous administration of nascent peptide imaging luciferase mRNA (1mg/kg) to rats, mRNA levels in various tissues and serum were quantified using both assays. Statistical analyses, including Bland-Altman, Deming regression and Passing-Bablok regression, were employed to assess method comparability and reproducibility. The results indicated that mRNA pharmacokinetics measured by branched DNA and RT-qPCR were largely consistent across tissues, with RT-qPCR showing greater reproducibility across multiple laboratories. RT-qPCR also demonstrated a wider dynamic range and higher sensitivity, making it a more versatile option for large-scale studies. Despite some differences in data due to tissue types and timepoints, both methods provided comparable pharmacokinetic profiles for mRNA quantification. This study underscores the importance of selecting an appropriate quantification method based on study requirements and highlights RT-qPCR's adaptability for multisite research, especially for the clinical development of mRNA-based therapeutics.

Mandarin Peels-Derived Carbon Dots: A Multifaceted Fluorescent Probe for Cu(II) Detection in Tap and Drinking Water Samples.

Carbon dots (CDs) derived from mandarin peel biochar (MBC) at different pyrolysis temperatures (200, 400, 600, and 800 °C) have been synthesized and characterized. This high-value transformation of waste materials into fluorescent nanoprobes for environmental monitoring represents a step forward towards a circular economy. In this itinerary, CDs produced via one-pot hydrothermal synthesis were utilized for the detection of copper (II) ions. The study looked at the spectroscopic features of biochar-derived CDs. The selectivity of CDs obtained from biochar following carbonization at 400 °C (MBC400-CDs towards various heavy metal ions resulted in considerable fluorescence quenching with copper (II) ions, showcasing their potential as selective detectors. Transmission electron microscopic (TEM) analysis validated the MBC-CDs' consistent spherical shape, with a particle size of <3 nm. The Plackett-Burman Design (PBD) was used to study three elements that influence the F0/F ratio, with the best ratio obtained with a pH of 10, for 10 min, and an aqueous reaction medium. Cu (II) was detected over a dynamic range of 4.9-197.5 μM and limit of detection (LOD) of 0.01 μM. Validation testing proved the accuracy and precision for evaluating tap and mountain waters with great selectivity and no interference from coexisting metal ions.

A CMOS Optoelectronic Transimpedance Amplifier Using Concurrent Automatic Gain Control for LiDAR Sensors

This paper presents a novel optoelectronic transimpedance amplifier (OTA) for short-range LiDAR sensors used in 180 nm CMOS technology, which consists of a main transimpedance amplifier (m-TIA) with an on-chip P+/N-well/Deep N-well avalanche photodiode (P+/NW/DNW APD) and a replica TIA with another on-chip APD, not only to acquire circuit symmetry but to also obtain concurrent automatic gain control (AGC) function within a narrow single pulse-width duration. In particular, for concurrent AGC operations, 3-bit PMOS switches with series resistors are added in parallel with the passive feedback resistor in the m-TIA. Then, the PMOS switches can be turned on or off in accordance with the DC output voltage amplitudes of the replica TIA. The post-layout simulations reveal that the OTA extends the dynamic range up to 74.8 dB (i.e., 1 µApp~5.5 mApp) and achieves a 67 dBΩ transimpedance gain, an 830 MHz bandwidth, a 16 pA/√Hz noise current spectral density, a −31 dBm optical sensitivity for a 10−12 bit error rate, and a 6 mW power dissipation from a single 1.8 V supply. The chip occupies a core area of 200 × 120 µm2.

Long-term stability of sufentanil quantified by UPLC-MS-MS in human plasma frozen for 11 years at -20°C.

The long-term stability of drug concentrations in human plasma samples when stored under normal laboratory conditions over several years is important for research purposes and clinical re-evaluation, but also for forensic toxicology. Fifty human plasma samples from a former clinical trial were re-analyzed after storage at -20°C for 11 years. Plasma samples were extracted using solid-phase extraction. Isotope labelled sufentanil-D5 was used as internal standard. Sufentanil plasma concentrations were determined by ultra-performance liquid chromatography (UPLC) with gradient elution, followed by tandem mass spectrometry with electrospray ionization. The linear dynamic range (LDR) was 25 - 2500 pg/mL, the limit of detection was 10 pg/mL, and the lower limit of quantification was 25 pg/mL. Intra- and inter-assay error did not exceed 6%. The deviation of the measured sufentanil plasma concentrations between the reanalysis and the first analysis was -63 ± 14% (mean ± SD). Therefore, sufentanil concentrations in human plasma were not stable in samples frozen at -20°C over 11 years.

Multiexposed Image-Fusion Strategy Using Mutual Image Translation Learning with Multiscale Surround Switching Maps

The dynamic range of an image represents the difference between its darkest and brightest areas, a crucial concept in digital image processing and computer vision. Despite display technology advancements, replicating the broad dynamic range of the human visual system remains challenging, necessitating high dynamic range (HDR) synthesis, combining multiple low dynamic range images captured at contrasting exposure levels to generate a single HDR image that integrates the optimal exposure regions. Recent deep learning advancements have introduced innovative approaches to HDR generation, with the cycle-consistent generative adversarial network (CycleGAN) gaining attention due to its robustness against domain shifts and ability to preserve content style while enhancing image quality. However, traditional CycleGAN methods often rely on unpaired datasets, limiting their capacity for detail preservation. This study proposes an improved model by incorporating a switching map (SMap) as an additional channel in the CycleGAN generator using paired datasets. The SMap focuses on essential regions, guiding weighted learning to minimize the loss of detail during synthesis. Using translated images to estimate the middle exposure integrates these images into HDR synthesis, reducing unnatural transitions and halo artifacts that could occur at boundaries between various exposures. The multilayered application of the retinex algorithm captures exposure variations, achieving natural and detailed tone mapping. The proposed mutual image translation module extends CycleGAN, demonstrating superior performance in multiexposure fusion and image translation, significantly enhancing HDR image quality. The image quality evaluation indices used are CPBDM, JNBM, LPC-SI, S3, JPEG_2000, and SSEQ, and the proposed model exhibits superior performance compared to existing methods, recording average scores of 0.6196, 15.4142, 0.9642, 0.2838, 80.239, and 25.054, respectively. Therefore, based on qualitative and quantitative results, this study demonstrates the superiority of the proposed model.

Development of an ionic liquid-based microextraction system (ILBME) for sensitive spectrophotometric analysis of neodymium(III) ions in environmental samples

ABSTRACT Introducing a precise, sensitive and simple system for determining neodymium(III) ions in aquatic samples could enhance the capabilities of routine instruments, particularly in terms of detection limits. Coupling a powerful preconcentration system, such as ionic liquid-based microextraction (ILBME), with a spectrophotometer can successfully achieve this goal. A sensitive and simple microextraction method based on a task-specific ionic liquid, designated [PDmim][Cl2], is described, in which the imidazolium-based ionic liquid served dual roles as both the chelating agent and the extraction phase. The ionic liquid was synthesized and characterized before being applied in microextraction procedure. The optimized microextraction results indicate that neodymium concentrations up to 5.10 µg L−1 can be successfully determined. The method characteristics, including the limit of detection (LOD), limit of quantification (LOQ), intra-day and inter-day relative standard deviations (RSDs), preconcentration factor (PF), enrichment factor (EF) and linear dynamic range (LDR), were found to be 1.53 µg L−1, 5.10 µg L−1, 3.83%, 4.44%, 123, 111.1 and 5.0–125.0 µg L−1, respectively. For method validation, the standard addition method using standard reference material (SRM) was employed, and the recovery range from real samples analyses was between 99.3% and 101.0%.

High sensitivity cameras can lower spatial resolution in high-resolution optical microscopy

High-resolution optical fluorescence microscopies and, in particular, super-resolution fluorescence microscopy, are rapidly adopting highly sensitive cameras as their preferred photodetectors. Camera-based parallel detection facilitates high-speed live cell imaging with the highest spatial resolution. Here, we show that the drive to use ever more sensitive, photon-counting image sensors in cameras can, however, have detrimental effects on the spatial resolution of the resulting images. This is particularly noticeable in applications that demand a high space-bandwidth product, where the image magnification is close to the Nyquist sampling limit of the sensor. Most scientists will often select image sensors based on parameters such as pixel size, quantum efficiency, signal-to-noise performance, dynamic range, and frame rate of the sensor. A parameter that is, however, typically overlooked is the sensor’s modulation transfer function (MTF). We have determined the wavelength-specific MTF of front- and back-illuminated image sensors and evaluated how it affects the spatial resolution that can be achieved in high-resolution fluorescence microscopy modalities. We find significant differences in image sensor performance that cause the resulting spatial resolution to vary by up to 28%. This result shows that the choice of image sensor has a significant impact on the imaging performance of all camera-based optical microscopy modalities.

Deep Learning-Enhanced Paper-Based Vertical Flow Assay for High-Sensitivity Troponin Detection Using Nanoparticle Amplification.

Successful integration of point-of-care testing (POCT) into clinical settings requires improved assay sensitivity and precision to match laboratory standards. Here, we show how innovations in amplified biosensing, imaging, and data processing, coupled with deep learning, can help improve POCT. To demonstrate the performance of our approach, we present a rapid and cost-effective paper-based high-sensitivity vertical flow assay (hs-VFA) for quantitative measurement of cardiac troponin I (cTnI), a biomarker widely used for measuring acute cardiac damage and assessing cardiovascular risk. The hs-VFA includes a colorimetric paper-based sensor, a portable reader with time-lapse imaging, and computational algorithms for digital assay validation and outlier detection. Operating at the level of a rapid at-home test, the hs-VFA enabled the accurate quantification of cTnI using 50 μL of serum within 15 min per test and achieved a detection limit of 0.2 pg/mL, enabled by gold ion amplification chemistry and time-lapse imaging. It also achieved high precision with a coefficient of variation of <7% and a very large dynamic range, covering cTnI concentrations over 6 orders of magnitude, up to 100 ng/mL, satisfying clinical requirements. In blinded testing, this computational hs-VFA platform accurately quantified cTnI levels in patient samples and showed a strong correlation with the ground truth values obtained by a benchtop clinical analyzer. This nanoparticle amplification-based computational hs-VFA platform can democratize access to high-sensitivity point-of-care diagnostics and provide a cost-effective alternative to laboratory-based biomarker testing.

High‐Gain and Tunable Linear Photodetection in 2D Tunneling Heterostructures Through Potential Engineering

Abstract2D materials are extensively employed in the fabrication of high‐performance photodetectors owing to their exceptional physical properties. However, most 2D material photodetectors fail to sustain high gain under intense illumination due to the limited intrinsic trap states. Here, an n‐n type Bi2O2Se/SnSe2 van der Waals tunneling heterojunction photodetector with a detection range from visible to near‐infrared (VIS‐NIR) is presented. Under reverse bias, the heterojunction induces a significant electron barrier and hole potential well, ensuring low leakage current and ample hole defect states. Therefore, the photodetector demonstrated a responsivity of 1636.3 AW−1 and a detectivity of 1.39 × 1014 Jones under 660 nm illumination, maintaining a tunable linear dynamic range (LDR) of ≈74.7 dB. This performance is attributed to the hole potential well‐suppressing the recombination of photogenerated carriers, thereby enhancing the device's gain. Furthermore, the tunneling of photogenerated electrons within the heterojunction's space charge region under bias enables rapid response (75.1 and 15.6 µs). In summary, the study introduces a novel strategy to overcome the limited detection capabilities of 2D devices under intense illumination, characterized by outstanding linearity for rapid detection and high‐resolution imaging.

RepDilPCR: a tool for automated analysis of qPCR assays by the dilution-replicate method

BackgroundThe dilution-replicate experimental design for qPCR assays is especially efficient. It is based on multiple linear regression of multiple 3-point standard curves that are derived from the experimental samples themselves and thus obviates the need for a separate standard curve produced by serial dilution of a standard. The method minimizes the total number of reactions and guarantees that Cq values are within the linear dynamic range of the dilution-replicate standard curves. However, the lack of specialized software has so far precluded the widespread use of the dilution-replicate approach.ResultsHere we present repDilPCR, the first tool that utilizes the dilution-replicate method and extends it by adding the possibility to use multiple reference genes. repDilPCR offers extensive statistical and graphical functions that can also be used with preprocessed data (relative expression values) obtained by usual assay designs and evaluation methods. repDilPCR has been designed with the philosophy to automate and speed up data analysis (typically less than a minute from Cq values to publication-ready plots), and features automatic selection and performance of appropriate statistical tests, at least in the case of one-factor experimental designs. Nevertheless, the program also allows users to export intermediate data and perform more sophisticated analyses with external statistical software, e.g. if two-way ANOVA is necessary.ConclusionsrepDilPCR is a user-friendly tool that can contribute to more efficient planning of qPCR experiments and their robust analysis. A public web server is freely accessible at https://repdilpcr.eu without registration. The program can also be used as an R script or as a locally installed Shiny app, which can be downloaded from https://github.com/deyanyosifov/repDilPCR where also the source code is available.

Investigation of optical fiber line with a positive transmission ratio of analog microwave signal

The influence of optical radiation power on the one-decibel compression point, harmonic distortion and dynamic range due to interference in a fiber-optic transmission line of an ultra-high frequency (microwave) signal has been studied. The line had a positive microwave signal transmission coefficient, and there were no amplification elements between the input and output. The amplification effect was achieved through the use of increased power of the carrier optical radiation and a photodetector with a high photocurrent. It has been shown that an increase in optical radiation power leads to a decrease in one-dB compression power and an increase in harmonic distortion, but an increase in optical radiation power does not lead to a change in the dynamic range of interference. It was found that the dynamic range free from interference was about 85…87 dB.

NeIle, a Genetically Encoded Indicator for Branched-Chain Amino Acids Based on mNeonGreen Fluorescent Protein and LIVBP Protein.

Branched-chain amino acids (BCAAs) play an important role in the functioning of mammalian cells and the central nervous system. However, available genetically encoded indicators for BCAAs are based on Förster resonance energy transfer and have a limited dynamic range. We developed a single fluorescent protein-based sensor for BCAAs, called NeIle, which is composed of circularly permutated mNeonGreen protein inserted into the leucine-isoleucine-valine binding protein (LIVBP) from Escherichia coli bacteria. In solution, the NeIle indicator displayed a positive fluorescence response to adding isoleucine, leucine, and valin amino acids with high ΔF/F dynamic ranges of 27-, 19-, and 11-fold and the corresponding affinity values of 5.0, 2.9, and 75 mM, respectively. The spectral and biochemical properties of the NeIle indicator were characterized in solution. We characterized the brightness of the NeIle indicator in living mammalian cells, including cultured neurons. Using the NeIle indicator, we successfully visualized the dynamics of isoleucine transients in different organelles of mammalian cells. We obtained and analyzed the X-ray crystal structure of the NeIle indicator in an isoleucine-bound state. Structure-guided directed mutagenesis of the NeIle indicator revealed the basis of its fluorescence response and selectivity to isoleucine.

High dynamic range land wavefield reconstruction from randomized acquisition

Compressive sensing (CS) is an alternative to regular Shannon sampling that captures similar information from reduced measurements. It relies on randomized sampling patterns and a sparse data representation to reconstruct the regularly sampled object. CS is an important ingredient in affordable seismic acquisition, which can lead to improvements in the near-surface mapping and noise suppression for land data. However, the near surface traps most of the source-generated energy, resulting in data that are rich in high-wavenumber content and have amplitudes spanning several orders of magnitude. When dealing with such high dynamic range nonstationary data, the Fourier domain is not optimal for providing a sparse representation — a necessary condition for successful application of CS. In contrast, a discrete complex wavelet transform can localize high-energy features, has good directional selectivity, and is near-shift invariant. Combined, these properties allow complex wavelets to represent detail-rich wavefields in a compact form. To leverage these features and achieve good CS reconstructions, we develop a scale- and orientation-dependent iterative soft thresholding (IST) scheme for reconstructing high dynamic range wavefields. Our approach requires little parameterization, is easy to implement, and is robust to reconstructed wavefield sampling grid and dynamic range. We test IST on different wavefields with randomly missing traces and compare the data reconstructions with the spectral projected gradient solver and projection onto convex sets. We quantify the reconstructions by a direct comparison of Fourier coefficients between fully sampled and reconstructed wavefields. Taking log10 of Fourier coefficients prior to computing the quality metric deemphasizes the importance of magnitude match while highlighting Fourier coefficient support accuracy, which usually translates into good structural fidelity of reconstructed data. We find that IST performs consistently among all examples, yielding good phase match while performing gentle denoising.

Rapid wavelength interval selection technology for multi-channel intensity-interrogation surface plasmon resonance imaging sensing

Intensity-interrogation surface plasmon resonance (I-SPR) provides the fastest imaging speed among various SPR techniques, including wavelength, phase, and angle-based detection. It also integrates easily with other devices and has substantial practical application potential. However, I-SPR's reliance on direct detection of reflected light intensity renders it sensitive to light source fluctuations and detector dark noise, and its dynamic range is relatively limited. To address these challenges, we have developed a multi-channel I-SPR sensing platform featuring rapid wavelength interval selection technology. This system optimizes the sensing wavelength according to the refractive indices of different samples, mitigating issues related to inconsistent SPR signals from various biomolecules. Our improved I-SPR technology enables high-throughput biomolecular detection with a refractive index range size of 2.035 × 10−2 for dynamic monitoring, reaching a leading role among the existing I-SPR technologies. This represents the widest linear dynamic range for I-SPR to date. Experimental results on protein binding kinetic constants KD are consistent with those obtained from commercially available instruments. We believe that this study is expected to accelerate the development of SPR technology toward broader biological applications.

Near-infrared-driven dual-photoelectrode photoelectrochemical sensing for fumonisin B1: Integrating a photon up-conversion bio-photocathode with an enhanced light-capturing photoanode

Fumonisin B1 (FB1), the most prevalent and highly toxic mycotoxin within the fumonisins family, poses threats to humans, especially in children and infants, even at trace levels. Therefore, it is essential to design an easy and sensitive detection strategy. Herein, a brand-new dual-photoelectrode photoelectrochemical (PEC) sensing platform for FB1 detection under near-infrared irradiation was unveiled. This platform integrated a photon up-conversion bio-photocathode substrate (UCNPs/Au/CuInS2, UCNPs: NaYF4: Yb3+, Er3+, Nd3+) and used a SnO2/SnS2@Bi/Bi2S3 heterojunction photoanode to greatly enhance light capture. Additionally, ZnO coated with polydopamine (ZnO@PDA) was utilized as a signal inhibitor. The restoration of photocurrent occurred due to the strong binding affinity between FB1 and its aptamer (FB1-Apt), facilitating the dissociation of FB1-Apt/ZnO@PDA from the photoelectrode. The PEC sensing performance and the electron transfer process were thoroughly examined. The developed “signal-restoration” PEC aptasensor exhibited a wider dynamic linear range from 1.0 × 10−3 to 1.0 × 102 ng/mL, with a lower limit of detection (0.13 pg/mL). It has demonstrated excellent practical detection performance in unspiked real samples, such as corn paste, with the FB1 enzyme-linked immunosorbent assay (ELISA) Kit serving as a reference, indicating its potential for routine analysis of other mycotoxins. Thus, this research establishes a feasible dual-photoelectrode PEC framework for the effective detection of mycotoxins and other hazardous substances.

Photoelectrochemical Immunoassay of Alpha‐Fetoprotein Based on Au Nanoparticles‐Decorated ZnO Microrods

AbstractHerein a split‐type photoelectrochemical (PEC) immunosensor based on in situ grown gold nanoparticles (Au NPs) on the surface of ZnO microrods (ZnO MRs) was devised for the detection of alpha‐fetoprotein (AFP) by employing dopamine (DA)‐loaded liposomes as the signal amplification strategy. Specifically, as the level of AFP rises, a proportional number of sandwich‐type immunocomplexes form in the well of the microplate, which can introduce a corresponding amount of DA‐encapsulated liposomes at the same time. Encapsulated DA molecules will be released with the stimulation of Triton X‐100, thereby resulting in the marked enhancement of the PEC signal. Under optimized conditions, the proposed PEC immunosensing platform displays specific photocurrent responses toward AFP in a broad dynamic working range of 0.05 −50 ng mL−1, achieving an impressively low limit of detection (LOD) of 18.7 pg mL−1. Furthermore, this methodology not only displays high specificity, and satisfactory storage stability but also ensures acceptable accuracy and practicality for the analytical applications of human serum samples.

Multi-view high-dynamic-range 3D reconstruction and point cloud quality evaluation based on dual-frame difference images

A high dynamic range can easily lead to image saturation, making it a challenge for structured light 3D reconstruction. The article proposes a multi-view 3D topography measurement system, which consists of dual projectors, a single camera, and a high-precision rotary platform. The system utilizes single-frame images to achieve high-dynamic-range surface adaptive exposure. Subsequently, it proposes a method that combines two-frame differential images with multi-view imaging to identify highly reflective regions and complete point cloud holes. This approach addresses the issue of visual blind spots caused by shadows and local high reflectivity due to the occlusion of the measured object’s geometric features. Finally, the system employs deep learning to evaluate the quality of the high-dynamic-range point cloud data. Comparative experiments show that optimal exposure in single-frame images can achieve better imaging quality and shorten capture time. The dual-frame difference image algorithm can identify high-reflection areas and complete the point cloud data. The point cloud quality evaluation model based on IT-PCQA demonstrates the effectiveness of the proposed method for high-dynamic-range 3D reconstruction.

HDR-CNF: single-image high dynamic range imaging based on conditional normalizing flows

HDR-CNF: single-image high dynamic range imaging based on conditional normalizing flows