A double helix-shaped optical fiber sensor for non-endoscopic diagnosis of gastrin-17.

Non-endoscopic tools for the diagnostic evaluation of patients should be promoted in the field of biomedical assay and the need for highly sensitive, efficient, low-cost, and user-friendly sensors must be considered. Optical fibers are widely used in sensors because their properties meet the physical requirements for biomedical detection. The spectrum responses of the sensor create changes in refractive index, wavelength shifts, and transmission loss. This study presents a double helix DNA-shaped optical fiber sensor for biosensors. The sensing principle of the DNA-shaped sensor is based on the whispering gallery mode (WGM) formed by the interference in the fiber's bending region. The refractive index interference changes corresponding to the core and cladding layers, which create shifts in the spectrum affected by the radius of the bend. A self-assembled sensor layer formed with nanoparticles was coated onto the DNA-shaped sensor in a sandwich structure. The wavelength shifts in spectral response are traced by the concentrations of gastrin-17 at 0.1, 1, 10, and 50 µg ml-1. The sensing layer was formed from a layer-by-layer assembly of gold nanoparticles to improve the performance of the surface plasmon resonance (SPR).

Real-Time and Sensitive Immunosensor for Label-Free Detection of Specific Antigen with a Comb of Microchannel Long-Period Fiber Grating.

This study aimed to develop a comb of microchannel and immunosensor based on long-period fiber grating using the process of Lithographie Galvanoformung Abformung-like micro-electromechanical systems (LIGA-like MEMS) for real-time and label-free detection of specific antigen. The coupling between propagating core and cladding modes was conducted from the comb of microchannel long-period fiber grating (CM-LPFG). The CM-LPFG-based immunosensor consisted of a microchannel structure through photoresist stacking processes and was sandwiched with an optical fiber to obtain a long-period structure. Specific immunoglobulin against protein antigen was immobilized onto an optical fiber surface and produced a real-time resonance effect on sensing specific protein antigen from the extracted protein mixtures of the cancer cell lines. The variable transmission loss was -14.07 dB, and the resonant wavelength shift was 11.239 nm. The low limit of detection for total protein concentration was 1.363 ng/µL. Our results revealed that the CM-LPFG-based immnosensor for real-time detection of label-free protein antigen is feasible and sensitive based on the diversification of a transmission loss and achieves specific immunosensing purposes for lab-on-fiber technology.

A Lamping U-Shaped Fiber Biosensor Detector for MicroRNA.

This study presents a U-shaped optical fiber developed for a facile application of microRNA detection. It is fabricated by the lamping process and packaged in a quartz tube to eliminate human negligence. In addition, silanization and electrostatic self-assembly are employed to bind gold nanoparticles and miRNA-133a probe onto the silicon dioxide of the fiber surface. For Mahlavu of hepatocellular carcinoma (HCC), detection is determined by the wavelength shift and transmission loss of a U-shaped optical fiber biosensor. The spectral sensitivity of wavelength and their coefficient of determination are found at -218.319 nm/ ng/mL and 0.839, respectively. Concurrently, the sensitivity of transmission loss and their coefficient of determination are found at 162.394 dB/ ng/mL and 0.984, respectively. A method for estimating the limit of detection of Mahlavu is at 0.0133 ng/mL. The results show that the proposed U-shaped biosensor is highly specific to miRNA-133a and possesses good sensitivity to variations in specimen concentration. As such, it could be of substantial value in microRNA detection.

Photoresist-free, laser-assisted chemical etching process for long-period fiber grating.

In this study, we propose a photoresist-free, laser-assisted wet chemical etching process used to control the grating depth of a long-period fiber grating (LPFG) termed laser-assisted etching LPFG (LLPFG). This process can considerably reduce production time, while the photoresist-free laser etching allows tiny long-period notches to be etched on the fiber surface, distinguishing the etching rate of the process from that of standard wet etching processes. The LLPFG, which has a period of 610 µm, was scanned using a KrF excimer laser. The results showed a resonant-attenuation wavelength of 1551 nm through a fiber diameter of 60 µm and a grating depth of 26 µm and to being a green process due to the photoresist-free etching.

Double Notched Long-Period Fiber Grating Characterization for CO2 Gas Sensing Applications †.

In this study, we applied a double-sided inductively coupled plasma (ICP) process to nanostructure long-period fiber grating (LPFG) in order to fabricate a double-notched LPFG (DNLPFG) sensor with a double-sided surface corrugated periodic grating. Using the sol-gel method, we also added thymol blue and ZnO to form a gas sensing layer, thus producing a DNLPFG CO2 gas sensor. The resulting sensor is the first double-sided etching sensor used to measure CO2. The experimental results showed that as the CO2 concentration increased, the transmission loss increased, and that the smaller the fiber diameter, the greater the sensitivity and the greater the change in transmission loss. When the diameter of the fiber was 32 µm (and the period was 570 µm) and the perfusion rate of CO2 gas was 15%, the maximum loss variation of up to 3.881 dB was achieved, while the sensitivity was 0.2146 dB/% and the linearity was 0.992. These results demonstrate that the DNLPG CO2 gas sensor is highly sensitive.

Glucose Sensor Using U-Shaped Optical Fiber Probe with Gold Nanoparticles and Glucose Oxidase.

In this study, we proposed a U-shaped optical fiber probe fabricated using a flame heating method. The probe was packaged in glass tube to reduce human factors during experimental testing of the probe as a glucose sensor. The U-shaped fiber probe was found to have high sensitivity in detecting the very small molecule. When the sensor was dipped in solutions with different refractive indexes, its wavelength or transmission loss changed. We used electrostatic self-assembly to bond gold nanoparticles and glucose oxidase (GOD) onto the sensor’s surface. The results over five cycles of the experiment showed that, as the glucose concentration increased, the refractive index of the sensor decreased and its spectrum wavelength shifted. The best wavelength sensitivity was 2.899 nm/%, and the linearity was 0.9771. The best transmission loss sensitivity was 5.101 dB/%, and the linearity was 0.9734. Therefore, the proposed U-shaped optical fiber probe with gold nanoparticles and GOD has good potential for use as a blood sugar sensor in the future.

Tilted Fiber Bragg Grating Sensor with Graphene Oxide Coating for Humidity Sensing.

In this study, we propose a tilted fiber Bragg grating (TFBG) humidity sensor fabricated using the phase mask method to produce a TFBG that was then etched with five different diameters of 20, 35, 50, 55 and 60 µm, after which piezoelectric inkjet technology was used to coat the grating with graphene oxide. According to the experimental results, the diameter of 20 µm yielded the best sensitivity. In addition, the experimental results showed that the wavelength sensitivity was -0.01 nm/%RH and the linearity was 0.996. Furthermore, the measurement results showed that when the relative humidity was increased, the refractive index of the sensor was decreased, meaning that the TFBG cladding mode spectrum wavelength was shifted. Therefore, the proposed graphene oxide film TFBG humidity sensor has good potential to be an effective relative humidity monitor.

A Small U-Shaped Bending-Induced Interference Optical Fiber Sensor for the Measurement of Glucose Solutions.

The study proposes a small U-shaped bending-induced interference optical fiber sensor; this novel sensor is a probe-type sensor manufactured using a mechanical device, a heat source, optical fiber and a packaging module. This probe-type sensor overcomes the shortcomings of conventional optical fibers, including being difficult to repair and a tendency to be influenced by external forces. We manufactured three types of sensors with different curvature radiuses. Specifically, sensors with three radiuses (1.5 mm, 2.0 mm, and 3.0 mm) were used to measure common water and glucose solutions with concentrations of between 6% and 30% (the interval between concentrations was 4%). The results show that the maximal sensitivity was 0.85 dB/% and that the linearly-dependent coefficient was 0.925. The results further show that not only can the small U-shaped bending-induced interference optical fiber sensor achieve high sensitivity in the measurement of glucose solutions, but that it can also achieve great stability and repeatability.

[Improving the Care Accuracy of Percutaneously Inserted Central Catheters Using Objective Structured Clinical Examination].

Approximately 9,800 adverse events related to medical tubing are reported in Taiwan every year. Most neonates in critical condition and premature infants acquire fluid, nutrition, and infusion solution using percutaneously inserted central catheters (PICCs). Objective structured clinical examination (OSCE) is an objective evaluative tool that may be used to measure the clinical competence of healthcare professionals. Very little is known about the effects of OSCE in Taiwan in terms of improving the accuracy of use of PICCs in nursing care and of reducing unexpected medical tubing removals. The present project aimed to explore the effects of an OSCE course on these two issues in the realms of standard operating procedures, care protocols, and training equipment at a neonatal intermediate unit in Taiwan. The duration of the present study ran from 2/20/2013 to 10/30/2013. The results showed that nurses' knowledge of PICCs improved from 87% to 91.5%; nurses' skill-care accuracy related to PICCs improved from 59.1% to 97.3%; and incidents of unexpected tube removals declined from 63.6% to 16.7%. This project demonstrated that OSCE courses improve the quality of PICC nursing care. Additionally, the instant feedback mechanism within the OSCE course benefited both teachers and students.

A packaged, low-cost, robust optical fiber strain sensor based on small cladding fiber sandwiched within periodic polymer grating.

In the present study, a novel packaged long-period fiber grating (PLPFG) strain sensor is first presented. The MEMS process was utilized to fabricate the packaged optical fiber strain sensor. The sensor structure consisted of etched optical fiber sandwiched between two layers of thick photoresist SU-8 3050 and then packaged with poly (dimethylsiloxane) (PDMS) polymer material to construct the PLPFG strain sensor. The PDMS packaging material was used to prevent the glue effect, wherein glue flows into the LPFG structure and reduces coupling strength, in the surface bonding process. Because the fiber grating was packaged with PDMS material, it was effectively protected and made robust. The resonance attenuation dip of PLPFG grows when it is loading. This study explored the size effect of the grating period and fiber diameter of PLPFG via tensile testing. The experimental results found that the best strain sensitivity of the PLPFG strain sensor was -0.0342 dB/µÎµ, and that an R2 value of 0.963 was reached.

Characterization of notched long-period fiber gratings: effects of periods, cladding thicknesses, and etching depths.

This study proposes using an inductively coupled plasma etching process to fabricate notched long-period fiber grating (NLPFG) for sensor applications. The effects of the designed parameters (i.e., different fiber cladding thicknesses, grating periods, and etching depths) are studied to explore the characterization of NLPFG. The characterization as indicated by tests of the NLPF showed that the wavelength of NLPFG produced a redshift with decreases in cladding thickness. The drift rate of the wavelength following changes in thickness was -2.801 nm/µm. In addition, a redshift also was exhibited in the increased period, with a wavelength drift rate corresponding to the size of the period of 1.466 nm/µm. Moreover, the results showed that the transmission loss in the spectra increased with etching depth. The variation rate of transmission loss based on etching depth was -0.458 dB/µm.

Immunosensing for Early Detection of Rheumatoid Arthritis Biomarkers: Anti-Cyclic Citrullinated Peptide Antibodies Based on Tilted-Fiber Bragg Grating Biosensor.

Rheumatoid arthritis (RA) is regarded as a chronic, immune-mediated disease that leads to the damage of various types of immune cells and signal networks, followed by inappropriate tissue repair and organ damage. RA is primarily manifested in the joints, but also manifests in the lungs and the vascular system. This study developed a method for the in vitro detection of RA through cyclic citrullinated peptide (CCP) antibodies and antigens. The diameter of a tilted-fiber Bragg grating (TFBG) biosensor was etched to 50 µm and then bonded with CCP antigens and antibodies. The small variations in the external refractive index and the optical fiber cladding were measured. The results indicated that the self-assembled layer of the TFBG biosensor was capable of detecting pre- and post-immune CCP antigen and CCP peptide concentrations within four minutes. A minimum CCP concentration of 1 ng/mL was detected with this method. This method is characterized by the sensor's specificity, ability to detect CCP reactions, user-friendliness, and lack of requirement for professional analytical skills, as the detections are carried out by simply loading and releasing the test samples onto the platform. This study provides a novel approach to medical immunosensing analysis and detection. Although the results for the detection of different concentrations of CCP antigen are not yet clear, it was possible to prove the concept that the biosensor is feasible even if the measurement is not easy and accurate at this stage. Further study and improvement are required.

Investigation of Sm Addition on Microstructural and Optical Properties of CoFe Thin Films.

CoFe-based alloys and rare earth (RE) elements are among the most studied materials in applying magnetic devices to improve soft magnetic characteristics. A series of Co40Fe40Sm20 films are deposited on a glass substrate via the sputtering technique, followed by an annealing process to investigate their effect on microstructural and optical properties of Co40Fe40Sm20 films. In this study, the increase in the thickness of Co40Fe40Sm20 films and annealing temperatures resulted in a smoother surface morphology. The 40 nm Co40Fe40Sm20 films annealed 300 °C are expected to have good wear resistance and adhesive properties due to their high values of H/E ratio and surface energy. Optical transparency also increased due to the smoother surface of the Co40Fe40Sm20 films.

A study on computer vision for facial emotion recognition.

Artificial intelligence has been successfully applied in various fields, one of which is computer vision. In this study, a deep neural network (DNN) was adopted for Facial emotion recognition (FER). One of the objectives in this study is to identify the critical facial features on which the DNN model focuses for FER. In particular, we utilized a convolutional neural network (CNN), the combination of squeeze-and-excitation network and the residual neural network, for the task of FER. We utilized AffectNet and the Real-World Affective Faces Database (RAF-DB) as the facial expression databases that provide learning samples for the CNN. The feature maps were extracted from the residual blocks for further analysis. Our analysis shows that the features around the nose and mouth are critical facial landmarks for the neural networks. Cross-database validations were conducted between the databases. The network model trained on AffectNet achieved 77.37% accuracy when validated on the RAF-DB, while the network model pretrained on AffectNet and then transfer learned on the RAF-DB results in validation accuracy of 83.37%. The outcomes of this study would improve the understanding of neural networks and assist with improving computer vision accuracy.

Thickness, Annealing, and Surface Roughness Effect on Magnetic and Significant Properties of Co40Fe40B10Dy10 Thin Films.

In this study, Co40Fe40B10Dy10 thin films were deposited using a direct current (DC) magnetron sputtering technique. The films were deposited on glass substrates with thicknesses of 10, 20, 30, 40, and 50 nm, and heat-treated in a vacuum annealing furnace at 100, 200, and 300 °C. Various instruments were used to examine and analyze the effects of roughness on the magnetic, adhesive, and mechanical properties. From the low frequency alternating current magnetic susceptibility (χac) results, the optimum resonance frequency is 50 Hz, and the maximum χac value tends to increase with the increase in the thicknesses and annealing temperatures. The maximum χac value is 0.18 at a film thickness of 50 nm and an annealing temperature of 300 °C. From the four-point probe, it is found that the resistivity and sheet resistance values decrease with the increase in film deposition thicknesses and higher annealing temperatures. From the magnetic force microscopy (MFM), the stripe-like magnetic domain distribution is more obvious with the increase in annealing temperature. According to the contact angle data, at the same annealing temperature, the contact angle decreases as the thickness increases due to changes in surface morphology. The maximal surface energy value at 300 °C is 34.71 mJ/mm2. The transmittance decreases with increasing film thickness, while the absorption intensity is inversely proportional to the transmittance, implying that the thickness effect suppresses the photon signal. Smoother roughness has less domain pinning, more carrier conductivity, and less light scattering, resulting in superior magnetic, electrical, adhesive, and optical performance.

The Influence of Annealing and Film Thickness on the Specific Properties of Co40Fe40Y20 Films.

Cobalt Iron Yttrium (CoFeY) magnetic film was made using the sputtering technique in order to investigate the connection between the thickness and annealing procedures. The sample was amorphous as a result of an insufficient thermal driving force according to X-ray diffraction (XRD) examination. The maximum low-frequency alternate-current magnetic susceptibility (χac) values were raised in correlation with the increased thickness and annealing temperatures because the thickness effect and Y addition improved the spin exchange coupling. The best value for a 50 nm film at annealing 300 °C for χac was 0.20. Because electron carriers are less constrained in their conduction at thick film thickness and higher annealing temperatures, the electric resistivity and sheet resistance are lower. At a thickness of 40 nm, the film's maximum surface energy during annealing at 300 °C was 28.7 mJ/mm2. This study demonstrated the passage of photon signals through the film due to the thickness effect, which reduced transmittance. The best condition was found to be 50 nm with annealing at 300 °C in this investigation due to high χac, strong adhesion, and low resistivity, which can be used in magnetic fields.

Surface Roughness-Induced Changes in Important Physical Features of CoFeSm Thin Films on Glass Substrates during Annealing.

Co60Fe20Sm20 thin films were deposited onto glass substrates in a high vacuum setting. The films varied in thickness from 10 to 50 nm and underwent annealing processes at different temperatures: room temperature (RT), 100, 200, and 300 °C. Our analysis encompassed structural, magnetic, electrical, nanomechanical, adhesive, and optical properties in relation to film thickness and annealing temperature. X-ray diffraction (XRD) analysis did not reveal characteristic peaks in Co60Fe20Sm20 thin films due to insufficient growth-driving forces. Electrical measurements indicated reduced resistivity and sheet resistance with increasing film thickness and higher annealing temperatures, owing to hindered current-carrier transport resulting from the amorphous structure. Atomic force microscope (AFM) analysis showed a decrease in surface roughness with increased thickness and annealing temperature. The low-frequency alternating current magnetic susceptibility (χac) values increased with film thickness and annealing temperature. Nanoindentation analysis demonstrated reduced film hardness and Young's modulus with thicker films. Contact angle measurements suggested a hydrophilic film. Surface energy increased with greater film thickness, particularly in annealed films, indicating a decrease in contact angle contributing to this increase. Transmittance measurements have revealed intensified absorption and reduced transmittance with thicker films. In summary, the surface roughness of CoFeSm films at different annealing temperatures significantly influenced their magnetic, electrical, adhesive, and optical properties. A smoother surface reduced the pinning effect on the domain walls, enhancing the χac value. Additionally, diminished surface roughness led to a lower contact angle and higher surface energy. Additionally, smoother surfaces exhibited higher carrier conductivity, resulting in reduced electrical resistance. The optical transparency decreased due to the smoother surface of Co60Fe20Sm20 films.

Perfectly notched long-period fiber grating filter based on ICP dry etching technique.

This study presents a new process using inductively a coupled plasma dry etching method to manufacture a long-period fiber grating filter with exact period, vertical sidewalls, and smooth etched surfaces, and the filter is thus named a perfectly notched long-period fiber grating (NLPFG). This process can dramatically reduce production time, and thereby provide higher volume production. The fabricated NLPFG has periods of 640 µm, resonant-attenuation wavelengths of 1518 nm, and maximum resonance-attenuation of 21.79 dB. A force induced loss-tunable calibration of the NLPFG filter was implemented, and a monotonically increasing quadratic fitting was observed. The results demonstrated that the proposed NLPFG has a much better period precision compared to corrugated LPFG, and it has great potential for a loss-tunable filter and force transducer applications.

Investigation of distinct welding parameters on mechanical and corrosion properties of dissimilar welded joints between stainless steel and low carbon steel.

The tensile strength and corrosion behavior of dissimilar welded joints are currently a subject of concern. In this work, gas metal arc welding (GMAW) and distinct welding parameters (welding current, arc voltage, and welding speed) were used to join 304 stainless steel (SUS304) and SS400 low carbon steel, and the ultimate tensile strength (UTS) of the dissimilar welded joints was investigated. A corrosion test was conducted by immersion in 3.5 wt.% sodium chloride (NaCl) solution for 7, 14, and 21 days. Based on tensile strength and Tafel testing, the welding parameters "Item 4" (welding current: 170 A, arc voltage: 20 V, welding speed: 40 cm/min) yielded good mechanical strength and low corrosion characteristics. The microstructure characterization showed that the area around the welded joints and SUS304 had more granular corrosion and corrosion tubercles with increasing immersion time. The chromium content gradually decreased. When exposed to the chloride environment, these welded joints easily underwent corrosion due to the loss of passivity. However, high-velocity oxygen-fuel (HVOF) spray used on the welded joints reduced the corrosion current density. Compared with the non-thermal spray sample (corrosion current density:7.49e - 05 A/cm2) while the corrosion current density (7.89e - 10 A/cm2) is five orders of magnitude lower. This spray effectively slowed down the corrosion rate of the welded joints and gave the structural objects good protection in the sodium chloride solution.

A U-Shaped Optical Fiber Temperature Sensor Coated with Electrospinning Polyvinyl Alcohol Nanofibers: Simulation and Experiment.

This study describes the fabrication of an electrospun, U-shaped optical fiber sensor for temperature measurements. The sensor is based on single mode fibers and was fabricated into a U-shaped optical fiber sensor through flame heating. This study applied electrospinning to coat PVA, a polymer, onto the sensor layer to reduce its sensitivity to humidity. The sensor is used to measure temperature variations ranging from 30 °C to 100 °C. The objectives of this study were to analyze the sensitivity variation of the sensor with different sensor layer thicknesses resulting from different electrospinning durations, as well as to simulate the wavelength signals generated at different electrospinning durations using COMSOL. The results revealed that the maximum wavelength sensitivity, transmission loss sensitivity, and linearity of the sensor were 25 dBm/°C, 70 pm/°C, and 0.956, respectively. Longer electrospinning durations resulted in thicker sensor layers and higher sensor sensitivity, that wavelength sensitivity of the sensor increased by 42%.