High-Sensitivity Optical Sensors Empowered by Quasi-Bound States in the Continuum in a Hybrid Metal-Dielectric Metasurface.

Enhancing light-matter interaction is a key requisite in the realm of optical sensors. Bound states in the continuum (BICs), possessing high quality factors (Q factors), have shown great advantages in sensing applications. Recent theories elucidate the ability of BICs with hybrid metal-dielectric architectures to achieve high Q factors and high sensitivities. However, the experimental validation of the sensing performance in such hybrid systems remains equivocal. In this study, we propose two symmetry-protected quasi-BIC modes in a metal-dielectric metasurface. Our results demonstrate that, under the normal incidence of light, the quasi-BIC mode dominated by dielectric can achieve a high Q factor of 412 and a sensing performance with a high bulk sensitivity of 492.7 nm/RIU (refractive index unit) and a figure of merit (FOM) of 266.3 RIU-1, while the quasi-BIC mode dominated by metal exhibits a stronger surface affinity in the biotin-streptavidin bioassay. These findings offer a promising approach for implementing metasurface-based sensors, representing a paradigm for high-sensitivity biosensing platforms.

Squeezed state in the hydrodynamic focusing regime for Escherichia coli bacteria detection.

Flow cytometry is an essential technique in single particle analysis and cell sorting for further downstream diagnosis, exhibiting high-throughput and multiplexing capabilities for many biological and biomedical applications. Although many hydrodynamic focusing-based microfluidic cytometers have been demonstrated with reduced size and cost to adapt to point-of-care settings, the operating conditions are not characterized systematically. This study presents the flow transition process in the hydrodynamic focusing mechanism when the flow rate or the Reynolds number increases. The characteristics of flow fields and mass transport were studied under various operating conditions, including flow rates and microchannel heights. A transition from the squeezed focusing state to the over-squeezed anti-focusing state in the hydrodynamic focusing regime was observed when the Reynolds number increased above 30. Parametric studies illustrated that the focusing width increased with the Reynolds number but decreased with the microchannel height in the over-squeezed state. The microfluidic cytometric analyses using microbeads and E. coli show that the recovery rate was maintained by limiting the Reynolds number to 30. The detailed analysis of the flow transition will provide new insight into microfluidic cytometric analyses with a broad range of applications in food safety, water monitoring and healthcare sectors.

Recent progress in quantum photonic chips for quantum communication and internet.

Recent years have witnessed significant progress in quantum communication and quantum internet with the emerging quantum photonic chips, whose characteristics of scalability, stability, and low cost, flourish and open up new possibilities in miniaturized footprints. Here, we provide an overview of the advances in quantum photonic chips for quantum communication, beginning with a summary of the prevalent photonic integrated fabrication platforms and key components for integrated quantum communication systems. We then discuss a range of quantum communication applications, such as quantum key distribution and quantum teleportation. Finally, the review culminates with a perspective on challenges towards high-performance chip-based quantum communication, as well as a glimpse into future opportunities for integrated quantum networks.

Optical coherence tomography in patients with Wilson's disease.

BACKGROUND: Morphological changes of retina in patients with Wilson's disease (WD) can be found by optical coherence tomography (OCT), and such changes had significant differences between neurological forms (NWD) and hepatic forms (HWD) of WD. The aim of this study was to evaluate the relationship between morphological parameters of retina and brain magnetic resonance imaging (MRI) lesions, course of disease, type of disease, and sexuality in WD. METHODS: A total of 46 WD patients and 40 health controls (HC) were recruited in this study. A total of 42 WD patients were divided into different groups according to clinical manifestations, course of disease, sexuality, and brain MRI lesions. We employed the Global Assessment Scale to assess neurological severity of WD patients. All WD patients and HC underwent retinal OCT to assess the thickness of inner limiting membrane (ILM) layer to retinal pigment epithelium layer and inner retina layer (ILM to inner plexiform layer, ILM-IPL). RESULTS: Compared to HWD, NWD had thinner superior parafovea zone (108.07 ± 6.89 vs. 114.40 ± 5.54 µm, p < .01), temporal parafovea zone (97.17 ± 6.65 vs. 103.60 ± 4.53 µm, p < .01), inferior parafovea zone (108.114 ± 7.65 vs. 114.93 ± 5.84 µm, p < .01), and nasal parafovea zone (105.53 ± 8.01 vs. 112.10 ± 5.44 µm, p < .01) in inner retina layer. Course of disease influenced the retina thickness. Male patients had thinner inner retina layer compared to female patients. CONCLUSION: Our results demonstrated that WD had thinner inner retina layer compared to HC, and NWD had thinner inner retina layer compared to HWD. We speculated the thickness of inner retina layer may be a potential useful biomarker for NWD.

Analysis of risk factors for neurological symptoms in patients with purely hepatic Wilson's disease at diagnosis.

OBJECTIVE: To analyze and explore the risk factors for neurological symptoms in patients with purely hepatic Wilson's disease (WD) at diagnosis. METHODS: This retrospective study was conducted at the First Affiliated Hospital of the Guangdong Pharmaceutical University on 68 patients with purely hepatic WD aged 20.6 ± 7.2 years. The physical examinations, laboratory tests, color Doppler ultrasound of the liver and spleen, and magnetic resonance imaging (MRI) of the brain were performed. RESULTS: The elevated alanine transaminase (ALT) and aspartate transaminase (AST) levels and 24-h urinary copper level were higher in the purely hepatic WD who developed neurological symptoms (NH-WD) group than those in the purely hepatic WD (H-WD) group. Adherence to low-copper diet, and daily oral doses of penicillamine (PCA) and zinc gluconate (ZG) were lower in the NH-WD group than those in the H-WD group. Logistic regression analysis showed that insufficient doses of PCA and ZG were associated with the development of neurological symptoms in patients with purely hepatic WD at diagnosis. CONCLUSION: The development of neurological symptoms in patients with purely hepatic WD was closely associated with insufficient doses of PCA and ZG, and the inferior efficacy of copper-chelating agents. During the course of anti-copper treatment, the patient's medical status and the efficacy of copper excretion should be closely monitored.

Substrate Signal Inhibition in Raman Analysis of Microplastic Particles.

In Raman analysis, the substrate material serves very often for signal enhancement, especially when metallic surfaces are involved; however, in other cases, the substrate has an opposite effect as it is the source of a parasitic signal preventing the observation of the sample material of interest. This is particularly true with the advent of microfluidic devices involving either silicon or polymer surfaces. On the other hand, in a vast majority of Raman experiments, the analysis is made on a horizontal support holding the sample of interest. In our paper, we report that a simple tilting of the supporting substrate, in this case, silicon, can drastically decrease and eventually inhibit the Raman signal of the substrate material, leading to an easier observation of the target analyte of the sample, in this case, microplastic particles. This effect is very pronounced especially when looking for tiny particles. Explanation of this trend is provided thanks to a supporting experiment and further numerical simulations that suggest that the lensing effect of the particles plays an important role. These findings may be useful for Raman analysis of other microscale particles having curved shapes, including biological cells.

Elderly onset of MELAS in a male: A case report.

Background: Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is one of the most common maternally inherited mitochondrial diseases which rarely affects elderly people. Case presentation: We reported the case of a 61-year-old male patient with MELAS. He was experiencing acute migraine-like headaches as the first symptoms. Laboratory data showed elevated lactate and creatine kinase levels. Brain magnetic resonance imaging (MRI) found a high signal intensity lesion in the left occipital-temporal-parietal lobe on diffusion-weighted imaging (DWI). Magnetic resonance angiography (MRA) revealed reversible vasoconstriction of the middle cerebral arteries and superficial temporal arteries. A muscle biopsy suggested minor muscle damage. A genetic study revealed a mitochondrial DNA A3243G mutation. Conclusion: Elderly onset of MELAS is rare and easily misdiagnosed as an ischemic stroke. MELAS with the onset of stroke-like episodes should be considered in adult or elderly patients with imaging findings that are atypical for cerebral infarction. The use of multimodal MRI in the clinical diagnosis of MELAS could be extremely beneficial.

Exploiting extraordinary topological optical forces at bound states in the continuum.

Polarization singularities and topological vortices in photonic crystal slabs centered at bound states in the continuum (BICs) can be attributed to zero amplitude of polarization vectors. We show that such topological features are also observed in optical forces within the vicinity of BIC, around which the force vectors wind in the momentum space. The topological force carries force topological charge and can be used for trapping and repelling nanoparticles. By tailoring asymmetry of the photonic crystal slab, topological force will contain spinning behavior and shifted force zeros, which can lead to three-dimensional asymmetric trapping. Several off-Γ BICs generate multiple force zeros with various force distribution patterns. Our findings introduce the concepts of topology to optical force around BICs and create opportunities to realize optical force vortices and enhanced reversible forces for manipulating nanoparticles and fluid flow.

Linear structural features of Wilson's disease and its correlation with neurological symptoms.

To measure the linear structure of the brain in patients with Wilson's disease (WD) and analyze its correlation with neurological symptoms. A total of 174 patients diagnosed with WD were enrolled. According to the type of clinical presentation, the patients with WD were divided into two groups: neurological (NWD) and hepatic (HWD). Sixty healthy volunteers were assigned to a control group. All patients with WD and healthy controls underwent brain magnetic resonance imaging (MRI). The severity of the neurological symptoms was assessed using the Burke Fahn Marsden Movement subscale (BFM-M). Linear brain measurements were performed using T1-weighted MRI scans of all the patients, and the correlation between these linear indices and BFM-M score was investigated. The Huckman index, third ventricle width, and sulcus width of the NWD group were significantly higher than those of the HWD and control groups (P < .05). The frontal horn index, ventricular index, and lateral ventricular body width index of the NWD group were significantly lower than those of the HWD and control groups (P < .05). The Huckman index and third ventricle width of the HWD group were higher than those of the control group (P < .05), whereas the body width index of the lateral ventricle was lower than that of the control group (P < .05). The BFM-M score correlated with the Huckman index (r = 0.29, P < .05), third ventricle width (r = 0.426, P < .001), and lateral ventricular body width index (r = -0.19, P < .05). This study demonstrated significant changes in the linear structure of patients with WD. Linear brain measurement analysis could be used as a potential method to assess the severity of neurological symptoms in WD.

Stable optical lateral forces from inhomogeneities of the spin angular momentum.

Transverse spin momentum related to the spin angular momentum (SAM) of light has been theoretically studied recently and predicted to generate an intriguing optical lateral force (OLF). Despite extensive studies, there is no direct experimental evidence of a stable OLF resulting from the dominant SAM rather than the ubiquitous spin-orbit interaction in a single light beam. Here, we theoretically unveil the nontrivial physics of SAM-correlated OLF, showing that the SAM is a dominant factor for the OLF on a nonabsorbing particle, while an additional force from the canonical (orbital) momentum is exhibited on an absorbing particle due to the spin-orbit interaction. Experimental results demonstrate the bidirectional movement of 5-µm-diameter particles on both sides of the beam with opposite spin momenta. The amplitude and sign of this force strongly depend on the polarization. Our optofluidic platform advances the exploitation of exotic forces in systems with a dominant SAM, facilitating the exploration of fascinating light-matter interactions.

Resource-efficient high-dimensional subspace teleportation with a quantum autoencoder.

Quantum autoencoders serve as efficient means for quantum data compression. Here, we propose and demonstrate their use to reduce resource costs for quantum teleportation of subspaces in high-dimensional systems. We use a quantum autoencoder in a compress-teleport-decompress manner and report the first demonstration with qutrits using an integrated photonic platform for future scalability. The key strategy is to compress the dimensionality of input states by erasing redundant information and recover the initial states after chip-to-chip teleportation. Unsupervised machine learning is applied to train the on-chip autoencoder, enabling the compression and teleportation of any state from a high-dimensional subspace. Unknown states are decompressed at a high fidelity (~0.971), obtaining a total teleportation fidelity of ~0.894. Subspace encodings hold great potential as they support enhanced noise robustness and increased coherence. Laying the groundwork for machine learning techniques in quantum systems, our scheme opens previously unidentified paths toward high-dimensional quantum computing and networking.

Inverse Optical Torques on Dielectric Nanoparticles in Elliptically Polarized Light Waves.

Elliptically polarized light waves carry the spin angular momentum (SAM), so they can exert optical torques on nanoparticles. Usually, the rotation follows the same direction as the SAM due to momentum conservation. It is counterintuitive to observe the reversal of optical torque acting on an ordinary dielectric nanoparticle illuminated by an elliptically or circularly polarized light wave. Here, we demonstrate that negative optical torques, which are opposite to the direction of SAM, can ubiquitously emerge when elliptically polarized light waves are impinged on dielectric nanoparticles obliquely. Intriguingly, the rotation can be switched between clockwise and counterclockwise directions by controlling the incident angle of light. Our study suggests a new playground to harness polarization-dependent optical force and torque for advancing optical manipulations.

Metasurface Micro/Nano-Optical Sensors: Principles and Applications.

Metasurfaces are 2D artificial materials consisting of arrays of metamolecules, which are exquisitely designed to manipulate light in terms of amplitude, phase, and polarization state with spatial resolutions at the subwavelength scale. Traditional micro/nano-optical sensors (MNOSs) pursue high sensitivity through strongly localized optical fields based on diffractive and refractive optics, microcavities, and interferometers. Although detections of ultra-low concentrations of analytes have already been demonstrated, the label-free sensing and recognition of complex and unknown samples remain challenging, requiring multiple readouts from sensors, e.g., refractive index, absorption/emission spectrum, chirality, etc. Additionally, the reliability of detecting large, inhomogeneous biosamples may be compromised by the limited near-field sensing area from the localization of light. Here, we review recent advances in metasurface-based MNOSs and compare them with counterparts using micro-optics from aspects of physics, working principles, and applications. By virtue of underlying the physics and design flexibilities of metasurfaces, MNOSs have now been endowed with superb performances and advanced functionalities, leading toward highly integrated smart sensing platforms.

Single Escherichia coli bacteria detection using a chemiluminescence digital microwell array chip.

Rapid and sensitive Escherichia coli (E. coli) detection is important in determining environmental contamination, food contamination, as well as bacterial infection. Conventional methods based on bacterial culture suffer from long testing time (24 h), whereas novel nucleic acid-based and immunolabelling approaches are hindered by complicated operation, the need of complex and costly equipment, and the lack of differentiation of live and dead bacteria. Herein, we propose a chemiluminescence digital microwell array chip based on the hydrolysis of 6-Chloro-4-methylumbelliferyl-ß-D-glucuronide by the ß-D-glucuronidase in E. coli to achieve fast single bacterial fluorescence detection. Taking the advantage of the picoliter microwells, single bacteria are digitally encapsulated in these microwells, thus the accurate quantification of E. coli can be realized by counting the number of positive microwells. We also show that the chemiluminescence digital microwell array chip is not affected by the turbidity of the test samples as well as the temperature. Most importantly, our method can differentiate live and dead bacteria through bacterial proliferation and enzyme expression, which is confirmed by detecting E. coli after pH and chlorination treatment. By comparing with the standard method of plate counting, our method has comparable performance but significantly reduces the testing time from over 24 h-2 h and 4 h for qualitative and quantitative analysis, respectively. In addition, the microfluidic chip is portable and easy to operate without external pump, which is promising as a rapid and on-site platform for single E. coli analysis in water and food monitoring, as well as infection diagnosis.

A patient with hereditary transthyretin amyloidosis involving multiple cranial nerves due to a rare p.(Phe84Ser) variant.

We report a 30-year-old man involving gastrointestinal symptoms, vitreous opacity, and multiple cranial neuropathies. Transthyretin-related hereditary amyloidosis genetic testing revealed a rare c.251T > C variant p.(Phe84Ser). Only four cases with this variant have been reported before.

Superhybrid Mode-Enhanced Optical Torques on Mie-Resonant Particles.

Circularly polarized light carries spin angular momentum, so it can exert an optical torque on the polarization-anisotropic particle by the spin momentum transfer. Here, we show that giant positive and negative optical torques on Mie-resonant (gain) particles arise from the emergence of superhybrid modes with magnetic multipoles and electric toroidal moments, excited by linearly polarized beams. Anomalous positive and negative torques on particles (doped with judicious amount of dye molecules) are over 800 and 200 times larger than the ordinary lossy counterparts, respectively. Meanwhile, a rotational motor can be configured by switching the s- and p-polarized beams, exhibiting opposite optical torques. These giant and reversed optical torques are unveiled for the first time in the scattering spectrum, paving another avenue toward exploring unprecedented physics of hybrid and superhybrid multipoles in metaoptics and optical manipulations.

Combined analysis of imaging tumor capsule with imaging tumor size guides the width of resection margin for solitary hepatocellular carcinoma.

BACKGROUND: The optimal width of resection margin (RM) for hepatocellular carcinoma (HCC) remains controversial. This study aimed to investigate the value of imaging tumor capsule (ITC) and imaging tumor size (ITS) in guiding RM width for patients with HCC. METHODS: Patients who underwent hepatectomy for HCC in our center were retrospectively reviewed. ITC (complete/incomplete) and ITS (≤ 3 cm/> 3 cm) were assessed by preoperative magnetic resonance imaging (MRI). Using subgroup analyses based on ITC and ITS, the impact of RM width [narrow RM (< 5 mm)/wide RM (≥ 5 mm)] on recurrence-free survival (RFS), overall survival (OS), and RM recurrence was analyzed. RESULTS: A total of 247 patients with solitary HCC were included. ITC and ITS were independent predictors for RFS and OS in the entire cohort. In patients with ITS ≤ 3 cm, neither ITC nor RM width showed a significant impact on prognosis, and the incidence of RM recurrence was comparable between the narrow RM and wide RM groups (15.6% vs. 4.3%, P = 0.337). In patients with ITS > 3 cm and complete ITC, the narrow RM group exhibited comparable RFS, OS, and incidence of RM recurrence with the wide RM group (P = 0.606, 0.916, and 0.649, respectively). However, in patients with ITS > 3 cm and incomplete ITC, the wide RM group showed better RFS and OS and a lower incidence of RM recurrence compared with the narrow RM group (P = 0.037, 0.018, and 0.046, respectively). CONCLUSIONS: As MRI-based preoperative markers, conjoint analysis of ITC with ITS aids in determining RM width for solitary HCC patients. Narrow RM is applicable in patients with ITS ≤ 3 cm regardless of ITC status and in those with ITS > 3 cm and complete ITC. Wide RM is preferred in those with ITS > 3 cm and incomplete ITC.

High-efficient subwavelength-scale optofluidic waveguides with tapered microstructured optical fibers.

Microstructured optical fibers (MOFs) have attracted intensive research interest in fiber-based optofluidics owing to their ability to have high-efficient light-microfluid interactions over a long distance. However, there lacks an exquisite design guidance for the utilization of MOFs in subwavelength-scale optofluidics. Here we propose a tapered hollow-core MOF structure with both light and fluid confined inside the central hole and investigate its optofluidic guiding properties by varying the diameter using the full vector finite element method. The basic optical modal properties, the effective sensitivity, and the nonlinearity characteristics are studied. Our miniature optofluidic waveguide achieves a maximum fraction of power inside the core at 99.7%, an ultra-small effective mode area of 0.38 µm2, an ultra-low confinement loss, and a controllable group velocity dispersion. It can serve as a promising platform in the subwavelength-scale optical devices for optical sensing and nonlinear optics.

Trapping and Detection of Single Viruses in an Optofluidic Chip.

Accurate single virus detection is critical for disease diagnosis and early prevention, especially in view of current pandemics. Numerous detection methods have been proposed with the single virus sensitivity, including the optical approaches and immunoassays. However, few of them hitherto have the capability of both trapping and detection of single viruses in the microchannel. Here, we report an optofluidic potential well array to trap nanoparticles stably in the flow stream. The nanoparticle is bound with single viruses and fluorescence quantum dots through an immunolabeling protocol. Single viruses can be swiftly captured in the microchannel by optical forces and imaged by a camera. The number of viruses in solution and on each particle can be quantified via image processing. Our method can trap and detect single viruses in the 1 mL serum or water in 2 h, paving an avenue for the advanced, fast, and accurate clinical diagnosis, as well as the study of virus infectivity, mutation, drug inhibition, etc.

Pangolin-Inspired Stretchable, Microwave-Invisible Metascale.

Microwave-invisible devices are emerging as a valuable technology in various applications, including soft robotics, shape-morphing structures, and textural camouflages, especially in electronic countermeasures. Unfortunately, conventional microwave-absorbing metastructures and bulk absorbers are stretching confined, limiting their application in deformable or special-shaped targets. To overcome such limitations, a conceptually novel soft-rigid-connection strategy, inspired by the pangolin, is proposed. Pangolin-inspired metascale (PIMS), which is a kind of stretchable metamaterial consisting of an electromagnetic dissipative scale (EMD-scale) and elastomer, is rationally designed. Such a device exhibits robust microwave-absorbing capacity under the interference of 50% stretching. Besides, profiting from the covering effect and size-confined effect of EMD-scale, the out-of-plane indentation failure force of PIMS is at least 5 times larger than conventional device. As a proof of concept, the proposed device is conformally pasted on nondevelopable surfaces. For a spherical dome surface, the maximum radar cross-section (RCS) reduction of PIMS is 6.3 dB larger than that of a conventional device, while for a saddle surface, the bandwidth of 10 dB RCS reduction exhibits an increase of 83%. In short, this work provides a conceptually novel platform to develop stretchable, nondevelopable surface conformable functional devices.