Study on the Design and Performance of a Glove Based on the FBG Array for Hand Posture Sensing.

This study introduces a new wearable fiber-optic sensor glove. The glove utilizes a flexible material, polydimethylsiloxane (PDMS), and a silicone tube to encapsulate fiber Bragg gratings (FBGs). It is employed to enable the self-perception of hand posture, gesture recognition, and the prediction of grasping objects. The investigation employs the Support Vector Machine (SVM) approach for predicting grasping objects. The proposed fiber-optic sensor glove can concurrently monitor the motion of 14 hand joints comprising 5 metacarpophalangeal joints (MCP), 5 proximal interphalangeal joints (PIP), and 4 distal interphalangeal joints (DIP). To expand the measurement range of the sensors, a sinusoidal layout incorporates the FBG array into the glove. The experimental results indicate that the wearable sensing glove can track finger flexion within a range of 0° to 100°, with a modest minimum measurement error (Error) of 0.176° and a minimum standard deviation (SD) of 0.685°. Notably, the glove accurately detects hand gestures in real-time and even forecasts grasping actions. The fiber-optic smart glove technology proposed herein holds promising potential for industrial applications, including object grasping, 3D displays via virtual reality, and human-computer interaction.

Microfluidic Biosensor Based on Molybdenum Disulfide (MoS2) Modified Thin-Core Microfiber for Immune Detection of Toxoplasma gondii.

Toxoplasma gondii (T. gondii) is a zoonotic parasite that is widely distributed and seriously endangers public health and human health. Therefore, accurate and effective detection of T. gondii is crucial. This study proposes a microfluidic biosensor using a thin-core microfiber (TCMF) coated with molybdenum disulfide (MoS2) for immune detection of T. gondii. The single-mode fiber was fused with the thin-core fiber, and the TCMF was obtained by arc discharging and flame heating. In order to avoid interference and protect the sensing structure, the TCMF was encapsulated in the microfluidic chip. MoS2 and T. gondii antigen were modified on the surface of TCMF for the immune detection of T. gondii. Experimental results showed that the detection range of the proposed biosensor for T. gondii monoclonal antibody solutions was 1 pg/mL to 10 ng/mL with sensitivity of 3.358 nm/log(mg/mL); the detection of limit was calculated to be 87 fg/mL through the Langmuir model; the dissociation constant and the affinity constant were calculated to be about 5.79 × 10-13 M and 1.727 × 1014 M-1, respectively. The specificity and clinical characteristics of the biosensor was explored. The rabies virus, pseudorabies virus, and T. gondii serum were used to confirm the excellent specificity and clinical characteristics of the biosensor, indicating that the proposed biosensor has great application potential in the biomedical field.

Classification of FLT3 inhibitors and SAR analysis by machine learning methods.

FMS-like tyrosine kinase 3 (FLT3) is a type III receptor tyrosine kinase, which is an important target for anti-cancer therapy. In this work, we conducted a structure-activity relationship (SAR) study on 3867 FLT3 inhibitors we collected. MACCS fingerprints, ECFP4 fingerprints, and TT fingerprints were used to represent the inhibitors in the dataset. A total of 36 classification models were built based on support vector machine (SVM), random forest (RF), eXtreme Gradient Boosting (XGBoost), and deep neural networks (DNN) algorithms. Model 3D_3 built by deep neural networks (DNN) and TT fingerprints performed best on the test set with the highest prediction accuracy of 85.83% and Matthews correlation coefficient (MCC) of 0.72 and also performed well on the external test set. In addition, we clustered 3867 inhibitors into 11 subsets by the K-Means algorithm to figure out the structural characteristics of the reported FLT3 inhibitors. Finally, we analyzed the SAR of FLT3 inhibitors by RF algorithm based on ECFP4 fingerprints. The results showed that 2-aminopyrimidine, 1-ethylpiperidine,2,4-bis(methylamino)pyrimidine, amino-aromatic heterocycle, [(2E)-but-2-enyl]dimethylamine, but-2-enyl, and alkynyl were typical fragments among highly active inhibitors. Besides, three scaffolds in Subset_A (Subset 4), Subset_B, and Subset_C showed a significant relationship to inhibition activity targeting FLT3.

Microfluidic immunosensor based on a graphene oxide functionalized double helix microfiber coupler for anti-Müllerian hormone detection.

A label-free microfluidic immunosensor based on the double helix microfiber coupler (DHMC) coated with graphene oxide (GO) was proposed for the specific detection of anti-Müllerian hormone (AMH). Two single-mode optical fibers were twisted in a parallel direction, the coning machine was used to fuse and taper them, and the high-sensitivity DHMC was obtained. To make a stable sensing environment, it was immobilized in a microfluidic chip. And then, the DHMC was modified by GO and bio-functionalized by the AMH monoclonal antibodies (anti-AMH MAbs) for the specific detection of AMH. The experimental results showed that the detection range of the immunosensor for AMH antigen solutions was 200 fg/mL∼50 µg/mL, the detection of limit (LOD) was ∼235.15 fg/mL, and the detection sensitivity and the dissociation coefficient were ∼3.518 nm/(log(mg/mL)) and ∼1.85 × 10 - 12 M, respectively. The alpha fetoprotein (AFP), des-carboxy prothrombin (DCP), growth stimulation expressed gene 2 (ST2) and AMH serum were used to confirm the excellent specific and clinical properties of the immunosensor, showing that the proposed immunosensor was easy-made and can be potentially applied in the biosensing field.

Noise Reduction Learning Based on XLNet-CRF for Biomedical Named Entity Recognition.

In recent years, Biomedical Named Entity Recognition (BioNER) systems have mainly been based on deep neural networks, which are used to extract information from the rapidly expanding biomedical literature. Long-distance context autoencoding language models based on transformers have recently been employed for BioNER with great success. However, noise interference exists in the process of pre-training and fine-tuning, and there is no effective decoder for label dependency. Current models have many aspects in need of improvement for better performance. We propose two kinds of noise reduction models, Shared Labels and Dynamic Splicing, based on XLNet encoding which is a permutation language pre-training model and decoding by Conditional Random Field (CRF). By testing 15 biomedical named entity recognition datasets, the two models improved the average F1-score by 1.504 and 1.48, respectively, and state-of-the-art performance was achieved on 7 of them. Further analysis proves the effectiveness of the two models and the improvement of the recognition effect of CRF, and suggests the applicable scope of the models according to different data characteristics.

Novel optical fiber Vernier immunosensor based on cascading Sagnac loops embedded with excessively tilted fiber grating for specific detection of canine distemper virus.

A novel optical fiber Vernier effect (VE) biosensor based on cascading Sagnac loops embedded with excessively tilted fiber grating (ExTFG) is proposed for the label free and specific detection of canine distemper virus (CDV). The VE was realized by cascading two different Sagnac loops with similar free spectrum range (FSR), one of which was integrated with panda-type polarization maintaining fiber (PMF) as the reference loop, and the other was embedded with ExTFG as the sensing loop. Owning to the amplified function of the VE, the refractive index (RI) sensitivity of the proposed sensing structure reached -1914.89 nm/RIU, which is approximately 12 times higher than that of the single ExTFG based RI sensor. Furthermore, the ExTFG in sensing loop was modified by graphene oxide (GO) and bio-functionalized by the CDV monoclonal antibodies (anti-CDV MAbs) for the specific detection of the CDV. Experimental results show that the proposed optical fiber Vernier sensor could detect the CDV in buffer solution with concentration as low as 1 pg/mL, and the sensitivity was about -1.18 nm/[log(mg/ml)] in the concentration range of 1 pg/mL ~ 50 ng/mL. The excellent specific and clinical properties of the biosensor were verified by immunoassays for fetal bovine serum, Toxoplasma gondii, rabies virus and CDV serum in sequence. Due to the sensitivity amplification function of VE, dense comb spectrum of the Sagnac loop and the stable interference spectra maintained by the polarized light, the proposed biosensor possesses the combined advantages of high sensitivity, high Q-factor and high stability, which may have potential applications in biosensing fields.

Hierarchical shared transfer learning for biomedical named entity recognition.

BACKGROUND: Biomedical named entity recognition (BioNER) is a basic and important medical information extraction task to extract medical entities with special meaning from medical texts. In recent years, deep learning has become the main research direction of BioNER due to its excellent data-driven context coding ability. However, in BioNER task, deep learning has the problem of poor generalization and instability. RESULTS: we propose the hierarchical shared transfer learning, which combines multi-task learning and fine-tuning, and realizes the multi-level information fusion between the underlying entity features and the upper data features. We select 14 datasets containing 4 types of entities for training and evaluate the model. The experimental results showed that the F1-scores of the five gold standard datasets BC5CDR-chemical, BC5CDR-disease, BC2GM, BC4CHEMD, NCBI-disease and LINNAEUS were increased by 0.57, 0.90, 0.42, 0.77, 0.98 and - 2.16 compared to the single-task XLNet-CRF model. BC5CDR-chemical, BC5CDR-disease and BC4CHEMD achieved state-of-the-art results.The reasons why LINNAEUS's multi-task results are lower than single-task results are discussed at the dataset level. CONCLUSION: Compared with using multi-task learning and fine-tuning alone, the model has more accurate recognition ability of medical entities, and has higher generalization and stability.

Optical Vernier sensor based on a cascaded tapered thin-core microfiber for highly sensitive refractive index sensing.

This study proposes a refractive index (RI) sensor using a cascaded tapered thin-core microfiber (TTCMF) based on the Vernier effect. The thin-core fiber was made into a TTCMF by arc discharging and flame heating and then sandwiched between two single-mode fibers (SMFs). The two structures with the same SMF-TTCMF-SMF but slightly different free spectral ranges (FSRs) were cascaded to generate the Vernier effect. The FSR varied with the taper parameters of TTCMF. The RI sensitivities of a single TTCMF sensor, series SMF-TTCMF-SMF sensor, and parallel SMF-TTCMF-SMF sensor were compared and analyzed. Using the Vernier effect in the RI measurement range from 1.3313 to 1.3392, a very high RI sensitivity of -15,053.411n m/R I U was obtained using the series SMF-TTCMF-SMF structure, and -16,723.243n m/R I U using the parallel structure, which were basically consistent with the simulation results. Compared with the RI sensitivity of the single TTCMF sensor, the RI sensitivities of series and parallel sensors were increased by 4.65 times and 5.16 times, respectively. In addition, in the temperature range from 35°C to 65°C, temperature sensitivities of -0.196n m/ ∘ C and -0.0489n m/ ∘ C were obtained using series and parallel structures, respectively; the corresponding temperature cross errors were 1.302×10-5 R I U/ ∘ C and 2.92×10-6 R I U/ ∘ C, respectively. Based on the advantages of high RI sensitivity, simple structure, low-temperature cross sensitivity, and convenient fabrication, the proposed sensors have great potential in biosensing fields.

Highly sensitive vibration sensor based on the dispersion turning point microfiber Mach-Zehnder interferometer.

In the present work, we introduced a highly sensitive vibration sensor, which is based on the dispersion turning point (DTP) microfiber Mach-Zehnder interferometer. The axial strain and vibration sensing characteristics of the microfiber Mach-Zehnder interferometer were investigated. First, we theoretically analyzed the spectrum evolution characteristics of the microfiber Mach-Zehnder interferometer caused by axial strain. Second, the microfiber with different diameters was fabricated using the electrode discharge and fused taper method, and the axial strain experiments were conducted; the maximum sensitivity of the DTP microfiber with a diameter of ∼2.2 µm reached -45.55 pm/µÉ› at ∼1550 nm. Finally, based on the axial strain principle of the microfiber, we designed a highly sensitive vibration sensor using a DTP microfiber integrated into a rectangular through-hole cantilever beam. The 30-3500 Hz vibration signal monitoring could be realized, the maximum signal-to-noise ratio (SNR) was ∼75 dB at 52 Hz, and the acceleration sensitivity reached as high as 0.764 V/g at 45Hz. These results suggested the high performance of the microfiber in axial strain and micro-vibration sensing fields.

Dual-peak long period fiber grating coated with graphene oxide for label-free and specific assays of H5N1 virus.

Avian influenza is an acute infectious disease caused by the avian influenza virus (AIV), which has caused enormous economic losses and posed considerable threats to public health. This study aimed to demonstrate an immunosensor based on dispersion turning point long-period fiber grating (DTP-LPFG) integrated with graphene oxide (GO) for the specific detection of a type of AIV H5N1 virus. LPFG was designed to work at DTP, whose dual-peak spacing was very high sensitive to a refractive index. Anti-H5N1 monoclonal antibodies were covalently bonded with the GO film on the fiber surface, thus constructing an immunosensor for the label-free and specific detection of the H5N1 virus. The proposed method was capable of the reliable detection of H5N1 virus with the limit of detection as low as ~1.05 ng/ml within the large range of 1 ng/mL to 25 µg/mL. More importantly, immunoassays of the whole H5N1 virus in clinical samples further confirmed that the GO-integrated DTP-LPFG immunosensor showed very high specificity to the H5N1 virus and demonstrated great potential for clinical use.

Label-free and specific detection of soluble programmed death ligand-1 using a localized surface plasmon resonance biosensor based on excessively tilted fiber gratings.

Programmed death ligand-1 (PD-L1) plays an important role in tumor evasion from the host immune system. The level of soluble PD-L1 (sPD-L1) in serum is closely related to tumor aggressiveness and outcomes. This study aimed to propose a localized surface Plasmon resonance (LSPR) biosensor based on excessively tilted fiber grating (ExTFG) coated with large-sized (∼160 nm) gold nanoshells for label-free and specific detection of sPD-L1. The experimental results showed that the limit of detection (LOD) of the immunosensor for sPD-L1 in buffer solutions was ∼1 pg/mL due to the enhanced LSPR effect resulting from the interaction between sPD-L1 molecules and anti-sPD-L1 monoclonal antibodies. The detection of sPD-L1 in complex serum media, such as fetal bovine serum, confirmed that the label-free immunosensor was extremely specific to sPD-L1 and could identify it at a concentration as low as 5 pg/mL. Therefore, it can be potentially applied in clinic for the fast and early diagnosis of cancer.

Photochemical reflective optical fiber sensor for selective detection of phenol in aqueous solutions.

A photochemical fiber-optic sensor was developed by integrating a plastic optical fiber (POF), polymer membrane, gold mirror, and TiO2-based composite, and was shown to sensitively and selectively detect phenol in aqueous solution. The sensing element consisted of a thinned POF and visible-light-driven SiO2/N-doped TiO2 coating. The gold mirror was used to develop a reflective POF probe. The polymer membrane with high phenol permselectivity was employed to form a micro-channel between the membrane and probe. Our findings highlight the sensor's capability of phenol detection in aqueous solutions with high sensitivity of 0.294×10-3 (mg·L-1)-1, pH immunity ranging from 2.0 to 14.0, and high selectivity with a limit of detection of 30 µg·L-1.

Immunosensing platform with large detection range using an excessively tilted fiber grating coated with graphene oxide.

We report an immunosensing platform with a large detection range using an excessively tilted fiber grating (ExTFG) coated with graphene oxide (GO). ExTFG was inscribed in standard single-mode fiber; GO film was coated on the fiber surface through hydrogen bond. The effectiveness and uniformity of GO deposited on the ExTFG surface were investigated by field emission scanning electron microscopy and energy spectrum method. Bovine serum albumin (BSA) monoclonal antibodies (MAbs) were used as biometric units to link the GO film through a covalent bond for the specific detection of BSA, so as to evaluate the performances of the proposed biosensor. The whole dynamic immobilization process of BSA MAbs and BSA detection were observed by the spectral evolution of the sensor. Experimental results show that the fabricated GO-coated ExTFG biosensor has a large detection range from 1.5 nM-75 nM and fast response for BSA antigen; the limit of detection is ∼0.88 nM by using an optical spectrum analyzer with a resolution of 0.03 nm, and the dissociation constant KD and the affinity constant KA are calculated to be ∼6.66×10-9 M and ∼1.5×108 M-1, respectively. The proposed GO-coated ExTFG immunosensing platform could lay a foundation for the specific detection of other biomolecules.

Study on spectral and refractive index sensing characteristics of etched excessively tilted fiber gratings.

We investigated the spectral and refractive index (RI) sensing characteristics of the excessively tilted fiber grating (Ex-TFG) with different cladding diameters. The Ex-TFG is inscribed in standard single-mode fiber, and the cladding reduces from 125 µm to around 15 µm by the chemical etching method. Experimental results show that the number of cladding modes decreases, and the spacing of adjacent resonance peaks becomes larger and larger with the reduction of the cladding diameter in the observed wavelength range of 1250-1650 nm. The average RI sensitivity in the index region of 1.33-1.38, the one near 1.33, and the one at around 1.38 of the etched Ex-TFG with a diameter of 15 µm is ∼6.3, ∼5.3, and ∼6.67 fold compared to those of the no-etched Ex-TFG, respectively. Also, the RI sensing performances of the etched Ex-TFG with a diameter smaller than 30 µm are better than those of the Ex-TFG inscribed in SM1500 (4.2 µm/80 µm) fiber in the index region of 1.33. The proposed micronano Ex-TFG has higher RI sensitivity and a more compact structure in biosensing applications, compared to the standard Ex-TFGs and Ex-TFGs inscribed in SM1500 fiber.

Study on vibration sensing performance of an equal strength cantilever beam based on an excessively tilted fiber grating.

An equal strength cantilever beam vibration sensor based on an excessively tilted fiber grating (Ex-TFG) with light intensity demodulation is proposed. The basic principles and sensing characteristics of vibration sensing of an equal strength cantilever beam and Ex-TFG, the combination of which is applied into vibration sensing, are analyzed. An Ex-TFG is attached to the middle axis of an equal strength cantilever beam. As the vibration of a piezoelectric ceramic causes the equal strength cantilever beam to deform, the same and uniform deformation also occurs on the Ex-TFG. Experimental results show that when the thickness of the equal strength cantilever beam is 0.3 mm and the Ex-TFG is at transverse electric (TE) polarization state, the sensing performance is the best, with the maximum acceleration sensitivity reaching 81.065 mv·m-1·s2, and the fast Fourier transform (FFT) main frequency components of the sensing signal accounting for more than 80%. In addition, this sensor is stable in sensing performance, easy in demodulation, simple in structure, high in sensitivity, and easy in manufacture, applicable for the sensing and on-line monitoring of low-frequency vibration signals.

A novel immunosensor based on excessively tilted fiber grating coated with gold nanospheres improves the detection limit of Newcastle disease virus.

A novel immunosensor for detecting Newcastle disease virus (NDV) was developed using excessively tilted fiber grating (Ex-TFG) coated with gold nanospheres (AuNs). AuNs were coated on the Ex-TFG surface via Au-S bonds using 3-mercaptopropyltrimethoxysilane (MPTMS), and the activated staphylococcal protein A (SPA) was linked to AuNs by covalent bonds via cysteamine. AuNs greatly enhanced the impact of the analyte on the fiber cladding mode through the local surface Plasmon resonance (LSPR) effect, thus improving the detection limit and sensitivity of the immunosensor. Meanwhile, SPA enhanced the bioactivity of anti-NDV monoclonal antibodies (MAbs), thus promoting the effectiveness of specific binding events on the fiber surface. Immunoassays were performed by monitoring the resonance wavelength shift of the proposed sensor under NDV samples containing different particle amounts. Specificity was assessed, and clinical tests for NDV were performed by contrast experiments. Experimental results showed that the detection limit for NDV was about 5~10 times improved compared to that of reference Ex-TFG without AuN treatment. Moreover, the novel biosensor was reusable and could potentially be applied in clinic.

Wet etching technique for fabrication of a high-quality plastic optical fiber sensor.

In this study, a simple wet etching technique is developed by employing aqueous solutions of acetic acid and ultrasonic irradiation for the fabrication of a high-quality plastic optical fiber (POF) sensor. The effects of acetic acid concentration and temperature and ultrasonic power on the etching rate and surface morphology of the etched POFs are investigated. The transmission spectrum and sensitivity of the etched POF sensors are evaluated using glucose solutions. We discovered that the POF sensors, which are fabricated using an aqueous solution of acetic acid with a concentration of 80 vol. % under an ultrasonic power of 130 W and temperature of 25°C, exhibit good light transmission and a high sensitivity of 9.10 [(RIU)(g/L)]-1 in the glucose solutions.

Luminous exothermic hollow optical elements for enhancement of biofilm growth and activity.

In this work, we present a luminous-exothermic hollow optical element (LEHOE) that performs spectral beam splitting in the visible spectral range for the enhancement of biofilm growth and activity. The LEHOE is composed of a four-layer structure with a fiber core (air), cladding (SiO2), coating I (LaB6 film), and coating II (SiO2-Agarose-Medium film). To clarify the physical, optical and photothermal conversion properties of the LEHOE, we determined the surface morphology and composition of the coating materials, and examined the luminous intensity and heating rate at the LEHOE surface. The biofilm activity on the biocompatible LEHOE is far greater than that of commercial fibers, and the biofilm weight on the LEHOE is 4.5 × that of the uncoated hollow optical element.

Human heart failure biomarker immunosensor based on excessively tilted fiber gratings.

A label-free immunosensor platform based on excessively tilted fiber gratings (Ex-TFGs) was developed for highly specific and fast detection of human N-terminal pro-B-type natriuretic peptide (NT-proBNP), which is considered a powerful biomarker for prognosis and risk stratification of heart failure (HF). High-purity anti-NT-proBNP monoclonal antibodies (MAbs) prepared in our laboratory were immobilized on fiber surface through the staphylococcal protein A (SPA) method for subsequent specific binding of the targeted NT-proBNP. Utilizing fiber optic grating demodulation system (FOGDS), immunoassays were carried out in vitro by monitoring the resonance wavelength shift of Ex-TFG biosensor with immobilized anti-NT-proBNP MAbs. Lowest detectable concentration of ~0.5ng/mL for NT-proBNP was obtained, and average sensitivity for NT-proBNP at a concentration range of 0~1.0 ng/mL was approximately 45.967 pm/(ng/mL). Several human serum samples were assessed by the proposed Ex-TFG biomarker sensor, with high specificity for NT-proBNP, indicating potential application in early diagnosing patients with acute HF symptoms.

Label-free immunoassay for porcine circovirus type 2 based on excessively tilted fiber grating modified with staphylococcal protein A.

Using excessively tilted fiber grating (Ex-TFG) inscribed in standard single mode fiber, we developed a novel label-free immunoassay for specific detection of porcine circovirus type 2 (PCV2), which is a minim animal virus. Staphylococcal protein A (SPA) was used to modify the silanized fiber surface thus forming a SPA layer, which would greatly enhance the proportion of anti-PCV2 monoclonal antibody (MAb) bioactivity, thus improving the effectiveness of specific adsorption and binding events between anti-PCV2 MAbs and PCV2 antigens. Immunoassay experiments were carried out by monitoring the resonance wavelength shift of the proposed sensor under different PCV2 titer levels. Anti-PCV2 MAbs were thoroughly dissociated from the SPA layer by treatment with urea, and recombined to the SPA layer on the sensor surface for repeated immunoassay of PCV2. The specificity of the immunosensor was inspected by detecting porcine reproductive and respiratory syndrome virus (PRRSV) first, and PCV2 subsequently. The results showed a limit of detection (LOD) for the PCV2 immunosensor of ~9.371TCID50/mL, for a saturation value of ~4.801×10(3)TCID50/mL, with good repeatability and excellent specificity.