Research on Bearing Surface Scratch Detection Based on Improved YOLOV5.

Bearings are crucial components of machinery and equipment, and it is essential to inspect them thoroughly to ensure a high pass rate. Currently, bearing scratch detection is primarily carried out manually, which cannot meet industrial demands. This study presents research on the detection of bearing surface scratches. An improved YOLOV5 network, named YOLOV5-CDG, is proposed for detecting bearing surface defects using scratch images as targets. The YOLOV5-CDG model is based on the YOLOV5 network model with the addition of a Coordinate Attention (CA) mechanism module, fusion of Deformable Convolutional Networks (DCNs), and a combination with the GhostNet lightweight network. To achieve bearing surface scratch detection, a machine vision-based bearing surface scratch sensor system is established, and a self-made bearing surface scratch dataset is produced as the basis. The scratch detection final Average Precision (AP) value is 97%, which is 3.4% higher than that of YOLOV5. Additionally, the model has an accuracy of 99.46% for detecting defective and qualified products. The average detection time per image is 263.4 ms on the CPU device and 12.2 ms on the GPU device, demonstrating excellent performance in terms of both speed and accuracy. Furthermore, this study analyzes and compares the detection results of various models, demonstrating that the proposed method satisfies the requirements for detecting scratches on bearing surfaces in industrial settings.

Packaged WGM MBR sensor for high-performance temperature measurement using CNN-based multimode barcode images.

The whispering gallery mode (WGM) optical microresonator sensors are emerging as a promising platform for precise temperature measurements, driven by their excellent sensitivity, resolution and integration. Nevertheless, challenges endure regarding stability, single resonant mode tracking, and real-time monitoring. Here, we demonstrate a temperature measurement approach based on convolutional neural network (CNN), leveraging the recognition of multimode barcode images acquired from a WGM microbottle resonator (MBR) sensor with robust packaged microresonator-taper coupling structure (packaged-MTCS). Our work ensures not only a high sensitivity of -14.28 pm/℃ and remarkable resolution of 3.5 × 10-4 ℃ across a broad dynamic range of 96 ℃ but also fulfills the demands for real-time temperature measurement with an average detection accuracy of 96.85% and a speed of 0.68s per image. These results highlight the potential of high-performance WGM MBR sensors in various fields and lay the groundwork for stable soliton microcomb excitation through thermal tuning.

Microfluidics-aided fabrication of 3D micro-nano hierarchical SERS substrate for rapid detection of dual hepatocellular carcinoma biomarkers.

The simultaneous analysis of trace amounts of dual biomarkers is crucial in the early diagnosis, treatment, and prognosis of hepatocellular carcinoma (HCC). In this study, we prepared SERS-active hydrogel microparticles (SAHMs) with 3D hierarchical gold nanoparticles (AuNPs) micro-nanostructures by microdroplet technology and in situ synthesis, which demonstrated high reproducibility and sensitivity. Compared with traditional 2D SERS substrates, this newly prepared 3D SERS substrate provided a high density of nano-wrinkled structures and numerous AuNPs. Furthermore, a newly designed SERS-active substrate was proposed for the simultaneous microfluidic detection of AFP and AFU. The Raman signals of sandwich immunocomplexes on the surface of the SAHMs were measured for the trace analysis of these biomarkers. The proposed microfluidic platform achieved AFP and AFU detection in the range of 0.1-100 ng mL-1 and 0.01-100 ng mL-1, respectively, which represents a good response. Indeed, this platform is easy to fabricate, of low cost and has short detection time and comparable detection limits to other methods. As far as we know, this is the first study to achieve the simultaneous detection of AFP and AFU on a microfluidic platform. Therefore, we proposed a new simultaneous detection platform for dual HCC biomarkers that shows strong potential for the early diagnosis of HCC.

A micro-nano interface integrated SERS-based microfluidic sensor for miRNA detection using DNAzyme walker amplification.

BACKGROUND: Precise and specific miRNA detection plays a vital role in exploring development mechanisms of cancer disease, thereby it can significantly improve relevant prevention and treatment strategies. RESULTS: In this work, a surface-enhanced Raman spectroscopy (SERS)-based microfluidic chip has been devised with a microcone array SERS substrate (MCASS) for the miR-141 detection. This substrate excels in unique SERS activity and large surface area for DNA oligonucleotide modification. As the presence of miR-141, the DNAzyme walker induced cleavage reaction took place on the finely designed and prepared dual DNA conjugated SERS nanoprobes. The SERS nanoprobes can anchor on MCASS by the DNA hybridization that achieved an impressive detection limit in the femtomolar level. SIGNIFICANCE: With this integrated SERS-based microfluidic chip, we provided a miRNA detection strategy using DNAzyme walker amplification technology. It is believed that this strategy could be a powerful tool for miRNA detection and related cancer screening test.

Efficient 3D scanning measurement system based on asymmetric trinocular vision and a multi-line laser.

The laser scanning measurement system has a pivotal role in precision measurement thanks to the non-contacting and low-cost advantages, but traditional methods and systems are inadequate in terms of accuracy, efficiency, and adaptability. In this study, an efficient 3D scanning measurement system based on asymmetric trinocular vision and a multi-line laser is developed to improve the measurement performance. The system design, working principle, and 3D reconstruction method are explored, as well as the innovation of the developed system. Furthermore, an efficient multi-line laser fringes indexing method is presented based on K-means ++ clustering and hierarchical processing to improve processing speed with guaranteed accuracy, which is the key point of the 3D reconstruction method. Various experiments are conducted to verify the capability of the developed system, and the results show that the developed system fulfills measurement needs in adaptability, accuracy, effectiveness, and robustness. The developed system achieves better results than commercial probes for complex measurement conditions, and measurement precision can be achieved to within 18 µm.

An experimental study of the merging flow of polymer solutions in a T-shaped microchannel.

The merging flow through a T-junction is relevant to sample mixing and particle manipulation in microfluidic devices. It has been extensively studied for Newtonian fluids, particularly in the high inertial regime where flow bifurcation takes place for enhanced mixing. However, the effects of fluid rheological properties on the merging flow have remained largely unexplored. We investigate here the flow of five types of polymer solutions along with water in a planar T-shaped microchannel over a wide range of flow rates for a systematic understanding of the effects of fluid shear thinning and elasticity. It is found that the merging flow near the stagnation point of the T-junction can either be vortex dominated or have unsteady streamlines, depending on the strength of elasticity and shear thinning present in the fluid. Moreover, the shear thinning effect is found to induce a symmetric unsteady flow in comparison to the asymmetric unsteady flow in the viscoelastic fluids, the latter of which exhibits greater interfacial fluctuations.

Single-shot 3D shape measurement based on RGB dot patterns and stereovision: retraction.

The referenced article [Opt. Express30, 28220 (2022)10.1364/OE.466148] has been retracted by the authors.

An Adaptive Hybrid Sampling Method for Free-Form Surfaces Based on Geodesic Distance.

High precision geometric measurement of free-form surfaces has become the key to high-performance manufacturing in the manufacturing industry. By designing a reasonable sampling plan, the economic measurement of free-form surfaces can be realized. This paper proposes an adaptive hybrid sampling method for free-form surfaces based on geodesic distance. The free-form surfaces are divided into segments, and the sum of the geodesic distance of each surface segment is taken as the global fluctuation index of free-form surfaces. The number and location of the sampling points for each free-form surface segment are reasonably distributed. Compared with the common methods, this method can significantly reduce the reconstruction error under the same sampling points. This method overcomes the shortcomings of the current commonly used method of taking curvature as the local fluctuation index of free-form surfaces, and provides a new perspective for the adaptive sampling of free-form surfaces.

Rapid simultaneous SERS detection of dual myocardial biomarkers on single-track finger-pump microfluidic chip.

Acute myocardial infarction (AMI) is a serious disease with high mortality that afflicts many people around the world. The main cause of death from AMI was the inaccurate early diagnosis, which resulted from the medical treatment might be a delay. Therefore, it is crucial to achieve the rapid detection of AMI. The cardiac troponin I (cTnI) level in human serum may significantly increase as the myocardial membrane ruptured, and the creatine kinase-MB (CK-MB) was also associated with the AMI recurrence and the infarct size of myocardial infarction. Both of them are regarded as important cardiac biomarkers for the early diagnosis of AMI. Therefore, we chose these two cardiac biomarkers as indicators for simultaneous detection. We proposed a single-track finger-pump microfluidic chip for simultaneous surface-enhanced Raman scattering (SERS) detection of cTnI and CK-MB. The entire detection process takes only 5 min without the cumbersome syringe pump. Meanwhile, it enables multiple reagent additions and removals of the unbonded reactants. This microfluidic sensor employed "sandwich" immunoassays based on SERS nanoprobes, AMI biomarkers, and magnetic beads. It is possible to detect two cardiac biomarkers simultaneously in a single measurement, greatly simplifying the detection process and reducing the detection time. Magnetic beads with SERS nanoprobes were separated and captured in the microchamber by a round magnet integrated into the chip. Our results showed that the detection limits of cTnI and CK-MB could reach to 0.01 ng mL-1, respectively. The limit of detections (LODs) match with the clinical threshold values for AMI biomarkers. It is believed that the proposed single-track finger-pump microfluidic chip can be used as an effective tool for determining early AMI.

Accuracy improvement of multi-view 3D laser scanning measurements based on point cloud error correction and global calibration optimization.

Multi-camera laser scanning measurement is emerging as a pivotal element in three-dimensional (3D) optical measurements. It reduces occlusion and enables the gathering of more 3D data. However, it also increases the difficulty of system algorithms in obtaining high measurement accuracy. To improve the measurement accuracy, there is an urgent need to address global calibration and error correction issues caused by the employment of multi-view systems. An accuracy improvement method for multi-view 3D laser scanning measurements based on point cloud error correction and global calibration optimization is then proposed. First, a planar asymmetric circular grid target is designed to calibrate the cameras, laser planes, and initial global transformation matrices of the multi-view 3D laser scanning probe simultaneously. The influence of the position of the laser plane on the measurement error is analyzed and what we believe to be novel mathematical error influencing factors are then modelled for point accuracy. Furthermore, a believed to be novel error model based on the backpropagation (BP) neural network is established for the regression analysis of the mathematical error influencing factors and measurement deviations for each point based on the standard sphere plate measurement. The final measurement is optimized by the correction of point cloud for each camera of the multi-view system and the global calibration optimization based on the error model. The proposed method is reliable and easy to implement, since it only requires a standard sphere plate and a planar target. Several experiments show that the method can effectively improve the measurement accuracy of multi-view 3D laser scanning probe through point cloud error correction and calibration optimization.

SERS-Based Immunoassay of Myocardial Infarction Biomarkers on a Microfluidic Chip with Plasmonic Nanostripe Microcones.

We developed a new plasmonic nanostripe microcone array (PNMA) substrate-integrated microfluidic chip for the simultaneous surface-enhanced Raman scattering (SERS)-based immunoassay of the creatine kinase MB isoenzyme (CK-MB) and cardiac troponin (cTnI) cardiac markers. The conventional immunoassay usually employs a microtiter plate as the solid capture plate to form the immunocomplexes. However, the two-dimensional (2D) surface of the microtiter plate limits the capture efficiency of the target antigens due to the steric hindrance effect. To address this issue, a gold film-coated microcone array with nanostripes was developed that can provide a large surface area for capture antibody conjugation and serve as a SERS-active substrate. This unique nano-microhierarchical structure showed an excellent light trapping effect and induced surface plasmon resonance to further enhance the Raman signals of the SERS nanoprobes. It significantly improved the sensitivity and applicability of SERS-based immunoassay on the microfluidic chip. With this integrated microfluidic chip, we successfully performed the simultaneous detection of CK-MB and cTnI, and the detection limit can reach 0.01 ng mL-1. It is believed that the PNMA substrate-integrated microfluidic chip would play a critical role in the rapid and sensitive diagnostics of cardiac diseases.

An optical method based auto-collimation for measuring five degrees of freedom error motions of rotary axis.

The paper presents an optical method based on auto-collimation to simultaneously measure five degrees of freedom error motions of the rotary axis. The proposed method consists of the collimated lasers, beam splitters, focusing lens, quadrant photodiode detectors, a high-precision steel ball, and a special mirror fixed to the rotary axis. The mathematical model is established byoptical ray tracing, and the corresponding optical path is also simulated by OpticStudio. Meanwhile, an adjusting mechanism for X-Y micro-displacement, based on the elastic deformation of the material, is designed to adjust the installation eccentricity error of the high-precision steel ball. The calibration results of the proposed system demonstrate that the displacement errors are ±0.25 µm within the measuring range of ±10 µm, and the tilt angle errors are ±0.6 arcsec within the measuring range of ±25 arcsec. Taking a direct drive (DD) motor as the test object, the radial error motions of the rotary axis range from -3.2 to 4.1 µm, the axial error motions range from -4.9 to 4.7 µm, and the tilt error motions around the X and Y axes range from -2.8 to 1.8 arcsec and -2.6 to 2.0 arcsec, respectively.

Single-shot 3D shape measurement based on RGB dot patterns and stereovision.

One-shot projection structured light 3D measurement is a method to establish the stereo matching relationship and reconstruct 3D shape by projecting one pattern. However, the traditional stereo matching algorithm does not solve the problem of low matching accuracy and matching efficiency, which fundamentally limits the accuracy of 3D measurement. As the projector and imaging systems have daily higher resolution and imaging quality, RGB dots projection has more application prospects because of its ability to establish a stereo matching relationship through one projection. In this work, we proposed a single-shot 3D measurement method using line clustering stereo matching, and model correction methods. The projected RGB dots are extracted by slope differenced distribution and area constrained erosion method. Area constrained erosion can solve the problem of the segmented connected blobs caused by insufficient projection resolution. The clustering stereo matching method is utilized to coarse match the segmented center red points. A model correction method is utilized to restore and constrain the pattern that cannot be imaged. Experimental results demonstrated that our method achieves the best accuracy of about 0.089mm, better than the traditional disparity and RGB line method, which may shed light on the proposed method can accurately reconstruct the 3D surface.

Regulation of soliton inside microresonators with multiphoton absorption and free-carrier effects.

The influence of frequency detuning on the field in silicon microresonators with multiphoton absorption and FC effect is investigated. In this study, results show that frequency detuning facilitates soliton generation. With appropriate frequency detuning, not only bright solitons but also dark ones can be excited in silicon microresonators, which compensates for the absence of solitons with multiphoton absorption and FC. In particular, the larger the frequency detuning is, the wider is the combs spectrum with 2PA obtained. In order to excite the soliton efficiently, the regulation of frequency detuning with multiphoton absorption and FC effect is also studied. In regulating the frequency detuning process with 2PA, a progressively enhanced soliton can be formed in the region near zero detuning. In the tuning process, 3PA can generate bright and dark solitons respectively at various detuning intervals, and independent bright solitons can be observed in microresonators with 4PA. The research results are significant for studying the generation of solitons in silicon microresonators with multiphoton absorption and FC effect.

Absolute distance measurement to coaxial multi-targets based on optical balanced cross-correlation using a single femtosecond laser.

We describe a high-precision ranging method based on an optical balanced cross-correlation system with a scanning repetition rate using a single femtosecond laser. By scanning the repetition rate of a laser, measuring pulses can be overlapped with reference pulses. It is an effective method to make reference pulses overlap with coaxial multiple target pulses without additional mechanical devices. The overlapped pulses are launched to the optical balanced cross-correlation system, which improves the time resolution measurement to the attosecond level. Two nominal distances are measured, and an additional commercial laser interferometer is used as a comparison to evaluate the accuracy of our measurement system. Moreover, the thickness of three stacked glasses is measured by our measurement system to verify that this system can measure coaxial multiple targets more quickly than conventional optical balanced cross-correlation systems using a single optical frequency comb.

Green light-driven acetone gas sensor based on electrospinned CdS nanospheres/Co3O4 nanofibers hybrid for the detection of exhaled diabetes biomarker.

Morphological and structural characteristics of semiconductors have a significant impact on their gas sensing characteristics. Reasonable design and synthesis of heterojunctions with special structures can effectively improve sensor performance. Herein, a cobalt oxide (Co3O4) nanofibers/cadmium sulfide (CdS) nanospheres hybrid was synthesized by an electrospinning method combined with a hydrothermal method to detect acetone gas. By adjusting loading amount of CdS, the sensing performance of CdS/Co3O4 sensor for acetone at room temperature (25 °C) was greatly ameliorated. In particular, the response of CdS/Co3O4 to 50 ppm acetone gas increased by 25% under 520 nm green light, meanwhile, the response/recovery time was shortened to 5 s/4 s. This is attributed to the heterojunction formed between CdS and Co3O4 as well as the influence of light excitation on the carrier concentration of the surfaces. Meanwhile, the unique high-porosity fiber structure and the catalytic action of cobalt ions also play an essential role in improving the performance. Furthermore, practical diabetic breath was experimentally simulated and proved the potential of the sensor in the future application of disease-assisted diagnosis.

Spherical wavefront measurement on modified cyclic radial shearing interferometry.

We propose a radial shearing interferometric approach to measure spherical wavefronts as both of the reflective and transmissive optical configurations. The modified cyclic radial shearing interferometer uses a single lens in the optical layout, which can conveniently adjust the radial shearing ratio between two shearing spherical wavefronts, and the use of a polarization camera enables to reconstruct the wavefront by a single image. The wavefront mapped onto the camera plane can be identified and quantified throughout an optimized wavefront reconstruction algorithm. In the experiments, plano-convex lenses and concave mirrors were used to generate spherical wavefronts, and the proposed system was able to reconstruct the surface figures after system characterization and calibration. Further investigations were performed to evaluate the system measurement accuracy by the radius of curvature comparison with design value and a commercial Shack-Hartmann wavefront sensor.

Simultaneous single-cell phenotype analysis of hepatocellular carcinoma CTCs using a SERS-aptamer based microfluidic chip.

Hepatocellular carcinoma (HCC) is a harmful malady that truly debilitates human health, and hence it is of significance to isolate and on-line profile the phenotype of HCC cells for further diagnosis and therapy. We developed a novel strategy for efficient capture and in situ heterogeneous phenotype analysis of circulating tumor cells (CTCs) at the single-cell level based on surface-enhanced Raman scattering (SERS) fingerprint characteristics. Herein, a new microfluidic chip with lantern-like bypass structure was designed to capture CTCs by their large size from whole blood. Furthermore, two types of SERS-aptamer nanotags were fabricated, realizing spectral recognition of single CTCs in accordance with the surface membrane protein expression. Up to 84% of CTCs with a purity of 95% were captured from whole blood samples using the present SERS-aptamer based microfluidic chip at 20 µL min-1. The results showed that the proposed strategy can successfully identify HCC cell subtypes by SERS measurements, which was related to the clinical surface biomarkers. This may open a new avenue for serving as a powerful tool of cancer diagnosis and prognosis evaluation.

Electrospinning of Flexible Poly(vinyl alcohol)/MXene Nanofiber-Based Humidity Sensor Self-Powered by Monolayer Molybdenum Diselenide Piezoelectric Nanogenerator.

Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics. In this work, a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti3C2Tx (PVA/MXene) nanofibers film and monolayer molybdenum diselenide (MoSe2) piezoelectric nanogenerator (PENG) was reported for the first time. The monolayer MoSe2-based PENG was fabricated by atmospheric pressure chemical vapor deposition techniques, which can generate a peak output of 35 mV and a power density of 42 mW m-2. The flexible PENG integrated on polyethylene terephthalate (PET) substrate can harvest energy generated by different parts of human body and exhibit great application prospects in wearable devices. The electrospinned PVA/MXene nanofiber-based humidity sensor with flexible PET substrate under the driven of monolayer MoSe2 PENG, shows high response of ∼40, fast response/recovery time of 0.9/6.3 s, low hysteresis of 1.8% and excellent repeatability. The self-powered flexible humidity sensor yields the capability of detecting human skin moisture and ambient humidity. This work provides a pathway to explore the high-performance humidity sensor integrated with PENG for the self-powered flexible electronic devices.

Correction of the air refractive index using a two-color method for absolute distance measurement without a dead zone.

In the fields of satellite formation, large-scale manufacturing, and ultra-precision machining, high-precision ranging based on the femtosecond laser is one of the necessary technologies. However, the fluctuations of the air refractive index and the limited tuning range of repetition rate restrict the measurement precision and range. Using only one femtosecond comb that corrects the air refractive index simultaneously, a method for ranging without the dead zone of measurement is described. A delay optical path is established in the ranging system to eliminate the dead zone of measurement by a comb. Meanwhile, in order to ensure the consistency of the pulse sequence between the fundamental frequency beam and the second-harmonic beam after the delay optical path, the second-harmonic beam generates on the delay optical path after the fundamental harmonic passes the long fiber. A two-color method is used to correct the effect of the air refractive index. The experimental result demonstrates the measurement precision of 7.2 µm at ∼0.8m with correction of the air refractive index, and the precision of measurement is 8.4 µm at ∼2.2m. Finally, the maximum deviation between our system and the reference standard is 5.0 µm.