Ultrafast and Parts-per-Billion-Level MEMS Gas Sensors by Hetero-Interface Engineering of 2D/2D Cu-TCPP@ZnIn2S4 with Enriched Surface Sulfur Vacancies.

The primary challenge for resonant-gravimetric gas sensors is the synchronous improvement of the sensitivity and response time, which is restricted by low adsorption capacity and slow mass transfer in the sensing process and remains a great challenge. In this study, a novel 2D/2D Cu-TCPP@ZnIn2S4 composite is successfully constructed, in which Cu-TCPP MOF is used as a core substrate for the growth of 2D ultrathin ZnIn2S4 nanosheets with well-defined {0001} crystalline facets. The Cu-TCPP@ZnIn2S4 sensor exhibited high sensitivity (1.5 Hz@50 and 2.3 Hz@100 ppb), limit of detection (LOD: 50 ppb), and ultrafast (9 s @500 ppb) detection of triethylamine (TEA), which is the lowest LOD and the fastest sensor among the reported TEA sensors at room temperature, tackling the bottleneck for the ultrafast detection of the resonant-gravimetric sensor. These above results provide an innovative and easily achievable pathway for the synthesis of heterogeneous structure sensing materials.

Higher-Order Topological Insulators via Momentum-Space Nonsymmorphic Symmetries.

We theoretically construct a higher-order topological insulator (HOTI) on a Brillouin real projective plane enabled by momentum-space nonsymmorphic (k-NS) symmetries from synthetic gauge fields. Two anicommutative k-NS glide reflections appear in a checkerboard Z_{2} flux model, impose nonsymmorphic constraints on Berry curvature, and quantize bulk and Wannier-sector polarization nonlocally across different momenta. The model's bulk exhibits an isotropic quadrupole phase diagram, where the transition appears intrinsically from bulk gap closure. The model hosts the simultaneous presence of intrinsic and extrinsic HOTI features: in a ribbon geometry where one pair of boundaries gets open, the edge termination can induce boundary-obstructed topological phase within the symmetry-protected topological phase due to the breaking of k-NS symmetry. At last, we present a concrete design for the real projective plane quadrupole insulator and show how to measure the momentum glide reflection based on acoustic resonator arrays. Our results shed light on HOTIs on deformed Brillouin manifolds via k-NS symmetries.

Polarization variable line-space grating based on photoalignment liquid crystal.

The application of a liquid crystal (LC) in displays has driven the development of novel LC elements. In this Letter, polarization variable line-space (PVLS) gratings based on photoalignment are fabricated, and their variable-spacing properties are derived using the vector diffraction theory. Both transmissive and reflective PVLS gratings are fabricated to validate the correctness of the derivation. Experimental results indicate that PVLS gratings have a wider wavelength response bandwidth than that of polarization volume grating (PVG). PVLS gratings have angle selectivity, and a large incident angle causes wavelength blueshift. Additionally, the relationship between wavelength and focal length indicates its anomalous dispersion as a diffractive optical element. These results of photoalignment-based PVLS gratings provide valuable insights for the advancement of displays and have the potential to improve visual experiences.

Exploratory insights into prefrontal cortex activity in continuous glucose monitoring: findings from a portable wearable functional near-infrared spectroscopy system.

The escalating global prevalence of diabetes highlights an urgent need for advancements in continuous glucose monitoring (CGM) technologies that are non-invasive, accurate, and user-friendly. Here, we introduce a groundbreaking portable wearable functional near-infrared spectroscopy (fNIRS) system designed to monitor glucose levels by assessing prefrontal cortex (PFC) activity. Our study delineates the development and application of this novel fNIRS system, emphasizing its potential to revolutionize diabetes management by providing a non-invasive, real-time monitoring solution. Fifteen healthy university students participated in a controlled study, where we monitored their PFC activity and blood glucose levels under fasting and glucose-loaded conditions. Our findings reveal a significant correlation between PFC activity, as measured by our fNIRS system, and blood glucose levels, suggesting the feasibility of fNIRS technology for CGM. The portable nature of our system overcomes the mobility limitations of traditional setups, enabling continuous, real-time monitoring in everyday settings. We identified 10 critical features related to blood glucose levels from extensive fNIRS data and successfully correlated PFC function with blood glucose levels by constructing predictive models. Results show a positive association between fNIRS data and blood glucose levels, with the PFC exhibiting a clear response to blood glucose. Furthermore, the improved regressive rule principal component analysis (PCA) method outperforms traditional PCA in model prediction. We propose a model validation approach based on leave-one-out cross-validation, demonstrating the unique advantages of K-nearest neighbor (KNN) models. Comparative analysis with existing CGM methods reveals that our paper's KNN model exhibits lower RMSE and MARD at 0.11 and 8.96%, respectively, and the fNIRS data were highly significant positive correlation with actual blood glucose levels (r = 0.995, p < 0.000). This study provides valuable insights into the relationship between metabolic states and brain activity, laying the foundation for innovative CGM solutions. Our portable wearable fNIRS system represents a significant advancement in effective diabetes management, offering a promising alternative to current technologies and paving the way for future advancements in health monitoring and personalized medicine.

Longitudinal polarization manipulation based on all-dielectric terahertz metasurfaces.

Polarization modulation of electromagnetic waves plays an important role in the field of optics and optoelectronics. Current polarization optics are typically limited to the modulation in a single transverse plane. However, manipulating polarization along the longitudinal direction is also important for full-space polarization modulation. Here, we propose two kinds of all-dielectric terahertz metasurfaces for longitudinally spatial polarization manipulation. The metasurfaces are capable of controlling polarization along the propagation path, namely: i) a longitudinal bifocal metalens with different polarization states at each focal point, and ii) a versatile metalens can simultaneously generate a uniformly polarized focused beam and a vector beam with varying polarization along the propagation path. Furthermore, the measurement of the dielectric thickness is demonstrated based on the polarization modulation feature of the metalens. The proposed metasurfaces allow for effective polarization state alteration along the propagation path, exhibiting significant potential for applications in versatile light-matter interactions, optical communications, and quantum optics.

Air-Liquid Interface Microfluidic Monitoring Sensor Platform for Studying Autophagy Regulation after PM2.5 Exposure.

Undoubtedly, a deep understanding of PM2.5-induced tumor metastasis at the molecular level can contribute to improving the therapeutic effects of related diseases. However, the underlying molecular mechanism of fine particle exposure through long noncoding RNA (lncRNA) regulation in autophagy and, ultimately, lung cancer (LC) metastasis remains elusive; on the other hand, the related monitoring sensor platform used to investigate autophagy and cell migration is lacking. Herein, this study performed an air-liquid interface microfluidic monitoring sensor (AIMMS) platform to analyze human bronchial epithelial cells after PM2.5 stimulation. The multiomics analysis [RNA sequencing (RNA-seq) on lncRNA and mRNA expressions separately] showed that MALAT1 was highly expressed in the PM2.5 treatment group. Furthermore, RNA-seq analysis demonstrated that autophagy-related pathways were activated. Notably, the main mRNAs associated with autophagy regulation, including ATG4D, ATG12, ATG7, and ATG3, were upregulated. Inhibition or downregulation of MALAT1 inhibited autophagy via the ATG4D/ATG12/ATG7/ATG3 pathway after PM2.5 exposure and ultimately suppressed LC metastasis. Thus, based on the AIMMS platform, we found that MALAT1 might become a promising therapeutic target. Furthermore, this low-cost AIMMS system as a fluorescence sensor integrated with the cell-monitor module could be employed to study LC migration after PM2.5 exposure. With the fluorescence cell-monitoring module, the platform could be used to observe the migration of LC cells and construct the tumor metastasis model. In the future, several fluorescence probes, including nanoprobes, could be used in the AIMMS platform to investigate many other biological processes, especially cell interaction and migration, in the fields of toxicology and pharmacology.

Thermal tuning nanoprinting based on liquid crystal tunable dual-layered metasurfaces for optical information encryption.

Dynamic tuning metasurfaces represent a significant advancement in optical encryption techniques, enabling highly secure multichannel responses. This paper proposes a liquid crystal (LC) tunable dual-layered metasurface to establish a thermal-encrypted optical platform for information storage. Through the screening of unit cells and coupling of characteristics, a dynamic polarization-dependent beam-steering metasurface is vertically cascaded with an angular multiplexing nanoprinting metasurface, separated by a dielectric layer. By integrating high-birefringence LCs into dual-layered metasurfaces, the cascaded meta-system can achieve dynamic thermal-switching for pre-encoded nanoprinting images. This work provides a promising solution for developing compact dynamic meta-systems for customized optical storage and information encryption.

Continuous Nanomanufacturing of Inorganic Lead Halide Perovskite Nanocrystals with High-Concentration Precursors.

The microscale flow preparation scheme has been widely used in the preparation of inorganic perovskite nanocrystals (NCs). It is considered to be the most promising method for large-scale production. Recently, it has been suggested that increasing the precursor concentration can further improve efficiency, but there is still a lack of understanding of high-concentration synthesis. Here, we develop a microscale flow synthesis scheme using high-concentration precursors, and the typical concentration value in the reaction phase reaches 0.035 mol/L using cesium acetate. The CsPbBr3 NCs with sharp photoluminescence (PL) at 515.7 nm can be obtained, and their PL quantum yield after post-treatment exceeds 90%. The effect of the molar ratio of Pb/Cs (Rm), reaction time, reaction temperature, and excess ligands on this flow reaction is studied. Several new phenomena are observed in our experiment. At 120 °C, some Cs4PbBr6 NCs exist in addition to the usual CsPbBr3 nanoplatelets. Excess ligands lead to the formation of numerous Cs4PbBr6 NCs with a bright green PL, and these NCs will spontaneously transform into a nonemission form in the film. Moreover, mixed-halide CsPbBrxI3-x NCs and CsPbI3 NCs are also prepared in this scheme, and then they are used to obtain LEDs in a range of colors.

Liquid lens based holographic camera for real 3D scene hologram acquisition using end-to-end physical model-driven network.

With the development of artificial intelligence, neural network provides unique opportunities for holography, such as high fidelity and dynamic calculation. How to obtain real 3D scene and generate high fidelity hologram in real time is an urgent problem. Here, we propose a liquid lens based holographic camera for real 3D scene hologram acquisition using an end-to-end physical model-driven network (EEPMD-Net). As the core component of the liquid camera, the first 10 mm large aperture electrowetting-based liquid lens is proposed by using specially fabricated solution. The design of the liquid camera ensures that the multi-layers of the real 3D scene can be obtained quickly and with great imaging performance. The EEPMD-Net takes the information of real 3D scene as the input, and uses two new structures of encoder and decoder networks to realize low-noise phase generation. By comparing the intensity information between the reconstructed image after depth fusion and the target scene, the composite loss function is constructed for phase optimization, and the high-fidelity training of hologram with true depth of the 3D scene is realized for the first time. The holographic camera achieves the high-fidelity and fast generation of the hologram of the real 3D scene, and the reconstructed experiment proves that the holographic image has the advantage of low noise. The proposed holographic camera is unique and can be used in 3D display, measurement, encryption and other fields.

Broadband short-wave near-infrared-emitting phosphor MgNb2O6:Cr3+ for pc-LED applications.

Broadband short-wave near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have been attracting keen interest for miniature NIR spectroscopy, while still lacking sufficient novel broadband NIR-emitting phosphors. Herein, we report a novel MgNb2O6:Cr3+ polycrystalline phosphor with a broad NIR emission band centered at 970 nm and a large full-width at half-maximum of approximately 155 nm under excitation of bluish-green light at around 515 nm. The optimized phosphor MgNb2O6:1%Cr3+ features a high internal quantum efficiency (IQE) of ∼85.5% and a moderate external QE of 25.2%. The fluorescence properties determined by two distorted hexa-coordination octahedral sites (i.e. [MgO6] and [NbO6]), low crystal field strength (Dq/B ∼ 1.65), and Cr3+-doping concentration were systematically investigated for comprehensive understanding of photophysical mechanisms. Besides, this broadband NIR phosphor MgNb2O6:Cr3+ exhibits a moderate thermal quenching of 21.4%@373 K for pc-LED application. An NIR pc-LED self-built by combining the optimal phosphor with a commercial cyan of ∼515 nm exhibits an NIR output power increase from 3.19 to 11.38 mW as the drive current is varied from 40 to 220 mA. With the help of this prototype pc-LED device, multiple applications were successfully performed to clearly recognize blood vessel distributions in the human finger, penetrate a plastic cap, and distinguish multi-color text. Undoubtedly, further development of such broadband short-wave NIR-emitting phosphors will make novel pc-LED devices for significant applications in biomedical imaging, nondestructive safety detection, intelligent identification, etc.

Terahertz reconfigurable metasensor for specific recognition multiple and mixed chemical substances based on AIT fingerprint enhancement.

Terahertz (THz) fingerprint metasensing is an effective method to identify chemical substances in a rapid and non-destructive way. Currently, two main principles are used in THz metasensing: the change of the real part of permittivity causing the dip resonance frequency deviation, and the fingerprint peak of the imaginary part of permittivity causing the dip resonance splitting (absorption induced transparency, AIT). Most previous work investigated AIT detection for only single chemical substance. The suitable AIT metasensor structure are still required for simultaneously measurement of multiple and mixture chemical substances. In this manuscript, we proposed the N-order concentric rings metasensor for specific recognition multiple and mixed chemical substances based on AIT fingerprint enhancement. The structure has broadband multiple plasmonic resonance dips which are generated by near field dipole resonances. The equivalent circuit model was built to realize the reconfigurable function. Then, 5-order concentric rings structure was designed and fabricated for simultaneously specific recognition of four chemical substances (α-lactose, benzoic acid, vitamin B2 and 2, 5-dichloroanline). The influence of the real and imaginary part of the chemical substances' permittivity on AIT effect had discussed in details. Simulation results indicated that the frequency-deviation of the resonance dip can be stabilized and will not be changed when the concentration of chemical substances is over 20 mg/mL. As shifted plasmonic resonance peaks match the chemical substances' imaginary part of permittivity fingerprint spectra, the perfect AIT effect can be realized. The metasensor can simultaneously and non-destructively conduct a specific detection of α-lactose, benzoic acid, vitamin B2 and 2,5-dichloroanline, and their mixture. The limit of detections of α-lactose, benzoic acid, vitamin B2 and 2,5-dichloroanline are 8.61 mg/mL, 6.96 mg/mL, 7.54 mg/mL and 8.35 mg/mL, respectively. Also, the sensitivity of the metasensor can reach 0.00211, 0.00208, 0.00211 and 0.00219 (unit: 1/mg/mL), respectively. By utilizing one-way analysis of variance method, the possibility of recognition error for each chemical substance is lower than 0.001. Our metasensor provides a novel and accurate platform for THz fingerprint sensing.

Optically Transparent, Ultra-Broadband, and Water-Based Microwave Meta-absorber with ITO Metasurfaces.

A transparent in visible wavelengths and ultrabroadband microwave meta-absorber (MMA) based on indium tin oxide (ITO) metasurfaces and a water layer is proposed. After optimizing a series of structural parameters, the proposed MMA can achieve ultrabroadband absorption with an absorption efficiency of more than 90%, covering the frequency range of 9.44-120.92 GHz and a relative absorption bandwidth of 171%. Furthermore, the absorber has many advantages, such as optical transparency, polarization insensitivity, and wide-angle absorption for transverse electric (TE) and transverse magnetic (TM) polarization waves. Moreover, the proposed MMA with 15 × 15 unit cells was fabricated and tested. The fabricated MMA performs well in microwave absorption, as demonstrated by the well-matched experimental results with numerical simulations. These extraordinary advantages mentioned above show that this type of MMAs can be applied in the fields of electromagnetic (EM) stealth, optical windows, and energy collection in the future.

Autonomous nanorobots with powerful thrust under dry solid-contact conditions by photothermal shock.

Nanorobotic motion on solid substrates is greatly hindered by strong nanofriction, and powerful nanomotors‒the core components for nanorobotic motion‒are still lacking. Optical actuation addresses power and motion control issues simultaneously, while conventional technologies with small thrust usually apply to fluid environments. Here, we demonstrate micronewton-thrust nanomotors that enable the autonomous nanorobots working like conventional robots with precise motion control on dry surfaces by a photothermal-shock technique. We build a pulsed laser-based actuation and trapping platform, termed photothermal-shock tweezers, for general motion control of metallic nanomaterials and assembled nanorobots with nanoscale precision. The thrust-to-weight ratios up to 107 enable nanomotors output forces to interact with external micro/nano-objects. Leveraging machine vision and deep learning technologies, we assemble the nanomotors into autonomous nanorobots with complex structures, and demonstrate multi-degree-of-freedom motion and sophisticated functions. Our photothermal shock-actuation concept fundamentally addresses the nanotribology challenges and expands the nanorobotic horizon from fluids to dry solid surfaces.

3D free-assembly modular microfluidics inspired by movable type printing.

Reconfigurable modular microfluidics presents an opportunity for flexibly constructing prototypes of advanced microfluidic systems. Nevertheless, the strategy of directly integrating modules cannot easily fulfill the requirements of common applications, e.g., the incorporation of materials with biochemical compatibility and optical transparency and the execution of small batch production of disposable chips for laboratory trials and initial tests. Here, we propose a manufacturing scheme inspired by the movable type printing technique to realize 3D free-assembly modular microfluidics. Double-layer 3D microfluidic structures can be produced by replicating the assembled molds. A library of modularized molds is presented for flow control, droplet generation and manipulation and cell trapping and coculture. In addition, a variety of modularized attachments, including valves, light sources and microscopic cameras, have been developed with the capability to be mounted onto chips on demand. Microfluidic systems, including those for concentration gradient generation, droplet-based microfluidics, cell trapping and drug screening, are demonstrated. This scheme enables rapid prototyping of microfluidic systems and construction of on-chip research platforms, with the intent of achieving high efficiency of proof-of-concept tests and small batch manufacturing.

Comparing the ocular surface temperature and dry eye condition of keratoconus with normal eyes using infrared thermal imaging.

PURPOSE: This study was conducted to compare the ocular surface temperature in keratoconus eyes with that in normal eyes. METHODS: A total of 27 participants were enrolled, with 10 and 17 participants in the keratoconus and control groups, respectively. Participants in the control group underwent an ophthalmic slit lamp examination and ocular thermography, while an additional corneal tomography was performed for those in the keratoconus group. RESULTS: For patients with keratoconus, the mean upper eyelid temperature (UET) was 32.36 ± 1.02 °C, inner canthus temperature (ICT) was 34.25 ± 0.83 °C, outer canthus temperature (OCT) was 33.62 ± 0.96 °C, initial central corneal temperature (initial CCT) was 33.04 ± 1.03 °C, sixth-second CCT (6 s-CCT) was 32.67 ± 1.19 °C, and the mean change in CCT measured within 6 s (change in CCT within 6 s) was 0.36 ± 0.26 °C. For controls, the values for UET, ICT, OCT, initial CCT, 6 s-CCT, and change in CCT within 6 s were 32.35 ± 1.13 °C, 34.14 ± 0.91 °C, 33.51 ± 1.02 °C, 33.22 ± 1.01 °C, 32.99 ± 1.01 °C, and 0.22 ± 0.17 °C, respectively. Except for the change in CCT within 6 s (p = 0.022), no significant differences were observed in UET (p = 0.973), ICT (p = 0.659), OCT (p = 0.697), initial CCT (p = 0.556) or 6 s-CCT (p = 0.310) between the two groups. CONCLUSION: The keratoconus eyes showed faster changes in CCT and evaporation of tear film after opening the eyes. Therefore, the keratoconus eyes had a higher incidence of dry eye conditions.

Two-dimensional phase unwrapping based on U2-Net in complex noise environment.

This paper proposes applying the nested U2-Net to a two-dimensional phase unwrapping (PU). PU has been a classic well-posed problem since conventional PU methods are always limited by the Itoh condition. Numerous studies conducted in recent years have discovered that data-driven deep learning techniques can overcome the Itoh constraint and significantly enhance PU performance. However, most deep learning methods have been tested only on Gaussian white noise in a single environment, ignoring the more widespread scattered noise in real phases. The difference in the unwrapping performance of deep network models with different strategies under the interference of different kinds of noise or drastic phase changes is still unknown. This study compares and tests the unwrapping performance of U-Net, DLPU-Net, VUR-Net, PU-GAN, U2-Net, and U2-Netp under the interference of additive Gaussian white noise and multiplicative speckle noise by simulating the complex noise environment in the real samples. It is discovered that the U2-Net composed of U-like residual blocks performs stronger anti-noise performance and structural stability. Meanwhile, the wrapped phase of different heights in a high-level noise environment was trained and tested, and the network model was qualitatively evaluated from three perspectives: the number of model parameters, the amount of floating-point operations, and the speed of PU. Finally, 421 real-phase images were also tested for comparison, including dynamic candle flames, different arrangements of pits, different shapes of grooves, and different shapes of tables. The PU results of all models are quantitatively evaluated by three evaluation metrics (MSE, PSNR, and SSIM). The experimental results demonstrate that U2-Net and the lightweight U2-Netp proposed in this work have higher accuracy, stronger anti-noise performance, and better generalization ability.

Dense Convolutional Neural Network for Identification of Raman Spectra.

The rapid development of cloud computing and deep learning makes the intelligent modes of applications widespread in various fields. The identification of Raman spectra can be realized in the cloud, due to its powerful computing, abundant spectral databases and advanced algorithms. Thus, it can reduce the dependence on the performance of the terminal instruments. However, the complexity of the detection environment can cause great interferences, which might significantly decrease the identification accuracies of algorithms. In this paper, a deep learning algorithm based on the Dense network has been proposed to satisfy the realization of this vision. The proposed Dense convolutional neural network has a very deep structure of over 40 layers and plenty of parameters to adjust the weight of different wavebands. In the kernel Dense blocks part of the network, it has a feed-forward fashion of connection for each layer to every other layer. It can alleviate the gradient vanishing or explosion problems, strengthen feature propagations, encourage feature reuses and enhance training efficiency. The network's special architecture mitigates noise interferences and ensures precise identification. The Dense network shows more accuracy and robustness compared to other CNN-based algorithms. We set up a database of 1600 Raman spectra consisting of 32 different types of liquid chemicals. They are detected using different postures as examples of interfered Raman spectra. In the 50 repeated training and testing sets, the Dense network can achieve a weighted accuracy of 99.99%. We have also tested the RRUFF database and the Dense network has a good performance. The proposed approach advances cloud-enabled Raman spectra identification, offering improved accuracy and adaptability for diverse identification tasks.

UVB upconversion of LiYO2:Ho3+,Gd3+ for application in luminescence thermometry.

Development of novel ultraviolet (UV) upconversion materials has been emerging as a hot research topic for application in tunable UV lasers, photocatalysis, sterilization, tagging, and most recently luminescence thermometry. We readily synthesized a series of Ho3+/Gd3+ co-doped LiYO2 upconversion phosphors by a traditional high-temperature reaction. Under excitation from a blue ∼445 nm laser, LiYO2:Ho3+,Gd3+ polycrystalline powders yield intense sharp ultraviolet B (UVB) upconversion luminescence from Gd3+ 6Pj (j = 7/2, 5/2, 3/2) excited states. By means of steady and dynamic photoluminescence spectra, we systematically investigated the involved two-photon absorption upconversion as well as the accompanying energy transfer processes between Ho3+ and Gd3+ ions in the LiYO2 host lattice. Interestingly, the distinguishable UVB luminescence constituents from Gd3+ 6Pj excited states exhibit sensitive temperature dependence in a 353-673 K range. Shedding light on thermal equilibria between Gd3+ 6Pj UV-emitting levels, their luminescence intensity ratios follow Boltzmann statistics for the application of new luminescence thermometry. For the scheme of 6P7/2-6P3/2 thermally coupled levels, it works over a temperature range of 373-673 K with a maximum relative sensitivity (Sr) of about 1.07% K-1 at 373 K, and its 6P7/2-6P5/2 counterpart works over 353-533 K with a maximum Sr of about 0.83% K-1 at 353 K. Overall, our study provides a new pathway to develop UV upconversion materials, and promotes the application of Gd3+-related UV luminescence constituents in sensitive temperature sensing over a wide temperature range.

Two-level optical encryption platform via an electrically driven liquid-crystal-integrated tri-channel metasurface.

Metasurface-based optical encryption techniques have garnered significant attention due to their ultracompact nature and ability to support multichannel optical responses. Here, we present a liquid-crystal (LC)-integrated metasurface that enables polarized-encrypted amplitude and phase multiplexing. This approach allows for simultaneously realizing trifold displays of both meta-holography and meta-nanoprinting. By combining propagation and geometric phase modulation, we meticulously screen the unit cells of the metasurface, establishing a comprehensive structural dictionary. As a proof-of-concept, we developed an electrically driven advanced optical encryption platform that boasts multifunctional channels and two-level encryption capabilities. This study paves the way for advanced optical encryption and identification techniques.

Simultaneous amplification of DNA in a multiplex circular array shaped continuous flow PCR microfluidic chip for on-site detection of bacterial.

Based on time to place conversion, continuous flow polymerase chain reaction (CF-PCR) can realize a rapid amplification of DNA by running the PCR reagent in a serpentine microchannel but a larger space is required for each sample, which greatly reduces the efficiency of the CF-PCR. Herein, we propose a multiplex circular array shaped CF-PCR microfluidic chip for on-site detection of bacteria. There were 12 serpentine microchannels which were distributed on the disc in an annular form, and each microchannel consisted of an inlet for sample injection, and an outlet for the detection of the PCR products based on fluorescence. Samples could be simultaneously driven into each inlet by a one-to-twelve diverter through a syringe. Moreover, the method of adding fluorescent dyes at the end of the microchannel can solve the inhibition effect of excessive fluorescent dyes on the PCR reaction. The process finished with simultaneous amplification of 12 different target genes from Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Escherichia coli, and on-site detection of their corresponding positives within 23 min. The fastest detectable PCR reaction time was 5.38 ± 0.2 min at a flow rate of 1 mL h-1. For E. coli, the minimum detectable concentration was 2.5 × 10-3 ng µL-1 in this microfluidic system. Such a system can increase the throughput of CF-PCR for point-of-care testing of pathogens.