Tyramine plays a very important role in the proper gastrointestinal function of the human body. By detecting tyramine concentrations, it can be inferred whether the human body is performing normal activities. In this paper, a fiber optic biosensor based on a cladding-offset structure (COF) is proposed to measure tyramine solution at various concentrations. The evanescent field around the probe sensing region is enhanced by etching the probe sensing region with hydrofluoric acid. Due to the large surface area of the gold nanoparticles (AuNPs), likely to occur in the surface chemical reaction, which can be used to capture and recognize tyramine molecules. Therefore, AuNPs are immobilized on the surface of COF to further improve the sensitivity of the tyramine sensor probe. Tyrosinase enzyme is used to enhance the sensitivity of the sensor probe. The performance of the COF fiber sensor is tested by analyzing the transmitted intensity of the sensor. The experimental results demonstrate that the COF-based biosensor provides a good strategy for clinical applications.
Creatinine is a metabolite of human muscles that can be used to infer whether part of the kidneys is functioning properly. In this paper, a taper-in-taper fiber (TITF) based fiber optic biosensor is proposed for detecting the concentrations of creatinine solution and helps to diagnosis of kidney failure. The TITF structure used in this study is formed by fabricating a taper shape again in the tapered region of a normal taper optical fiber. This allows the fiber to produce more higher-order modes and thus improve its ability to sense changes in refractive index of the external environment. The sensitivity of the sensor was increased by coating the tapered region of the TITF fiber with a gold nanoparticles and zinc oxide nanomaterials. Creatinase enzyme is used to increase the specificity of the sensor for creatinine. The experimental results show that the sensor can detect the creatinine solution with the concentrations of 300-2000 μM and the sensitivity is 0.17 a.u./μM. It provides a good choice for biomedical applications.
In this study, a novel optical fiber sensor based on varying cladding diameters is developed to detect different tyramine concentrations. Single-mode fiber (SMF, 8.25/125 μm) and multimode fiber (MMF, 200/220 μm) are fused to form the SMF-MMF-SMF structure. The output signal is amplified by etching the fiber sensing region that can generate stronger evanescent fields. Multi-walled carbon nanotubes (MWCNTs) are used to enhance the sensing performance. The tyramine enzyme is used to functionalize the probe and realize the specificity of the probe for tyramine. The performance of the sensor is analyzed, and results show that the sensor has good selectivity. The results also show that the sensors based on different cladding diameters can be used as special sensors for measuring the concentration of tyramine.
Cholesterol plays an important role in biological systems, and the quantity of cholesterol in the human body serves as a diagnostic marker for a range of disorders. This article presents a localized surface plasmon resonance (LSPR) sensor based on dual-tapered optical fiber (DTOF) that can detect cholesterol levels in the human body. To stimulate the LSPR effect and increase the sensitivity of the sensing probe, gold nanoparticles were fixed on the DTOF’s surface. In this study, the reaction between cholesterol and cholesterol oxidase altered the refractive index near the sensing probe, and the related spectrum was obtained. In addition, the sensor’s performance, including linear range, repeatability, reusability, stability, and selectivity, was examined. The experimental results indicate that the proposed DTOF-based LSPR sensor is capable of reliably measuring cholesterol levels and has promising biomedical applications.
The detection of glucose level in human body is very necessary for motoring physical condition. In our work, a triple tapered sensor probe based localized surface plasmon resonance (LSPR) is developed to detect various glucose concentration solution. The single-mode fiber (SMF) is utilized to prepare the proposed triple tapered structure. The serial taper structure in the sensing area insure more evanescent wave (EW) leak out. Gold nanoparticles (AuNPs) are modified on the serial triple tapered fiber (STTF) structure to stimulate the LSPR phenomenon. The limit of detection (LOD) and sensitivity of sensor are 3.8 mM and 0.59 nm/mM, respectively. Moreover, the reproducibility, selectivity, pH test, and reusability of STTF probe are evaluated to validate the ability in practice.
In this study, a plasmon sensor based on a core mismatch optical fiber structure is proposed for measuring various creatinine concentrations. Creatinine is an important clinical biomarker for diabetes, kidney disease, renal failure, and muscle atrophy. The single-mode fiber (SMF) and multi-mode fiber (MMF) are used to fabricate the SMF-MMF-SMF-MMF-SMF (SMSMS) structure. Further, SMSMS fiber structure is etched with hydrofluoric (HF) acid, that results in more evanescent fields at the core-cladding interface. Gold nanoparticles (AuNPs) are immobilized on the surface of the optical fiber structure to activate the LSPR phenomenon. To validate the sensor's performance, the sensor's sensitivity, reusability, reproducibility, and selectivity are tested. The experimental results demonstrate that the fiber-optic sensor based on the SMSMS structure is capable of measuring creatinine concentrations over a wide range in aquaculture industry. This provides an excellent opportunity for the sensor to be used in biomedicine.
Cholesterol plays a very important role in human physiological function, and the level of cholesterol in human body is a marker for diagnosing a variety of diseases. The article proposes a localized surface plasmon resonance (LSPR) sensor based on dual-tapered optical fiber (DTOF) that can detect cholesterol concentrations in the human body. To excite the LSPR effect and improve the sensing probe's sensitivity, gold nanoparticles (AuNPs) were immobilized on the surface of the DTOF. In this work, the specific reaction between cholesterol and cholesterol oxidase led to the change of refractive index (RI) near the sensing probe, and the corresponding spectrum is collected. Additionally, the performance of the sensor was evaluated, including linear range, reproducibility, reusability, stability, and selectivity. The experimental results demonstrate that the proposed DTOF-based LSPR sensor is capable of detecting the cholesterol level accurately and has a promising application in biomedicine.
The core mismatch formed by the splicing of different fiber cores and tapered fiber is beneficial to the sensing. In this paper, a single-mode fiber (SMF)- tapered multi-mode fiber (tapered MMF)-single-mode fiber structure was fabricated and used as a sensor to detect uric acid. The gold nanoparticles (AuNPs)/zinc oxide (ZnO) nanoparticles were fixed on the tapered surface to enhance the localized surface plasmon resonance (LSPR) and its sensing performance. The experimental results show that the optical fiber sensor can detect different concentrations of uric acid solution successfully and has a linear response in a certain range for biomedical applications.
In this paper, localized surface plasmon resonance (LSPR) based tapered multimode optical fiber (TMMF) sensor is developed for the detection of different concentrations of p-cresol solutions. Gold nanoparticles (AuNPs) and molybdenum disulfide nanoparticles (MoS2-NPs) were immobilized on TMMF probes, respectively. The performance of the designed probe was explored by detecting the response of different concentrations of p-cresol solutions. The combination of AuNPs and MoS2-NPs enhances the sensitivity and anti-interference ability of the sensing probe. In this work, the enzymatic reaction of p-cresol solution and tyrosinase changes the RI in the vicinity of the probe and records the corresponding spectrum. The probe will also be evaluated in terms of linear range, limit of detection (LoD), reproducibility, reproducibility, stability, selectivity, etc.
In this work, a simple and effective sensor using single-mode fiber (SMF) tapered structure is developed to detect different concentrations of acetylcholine solutions, and its function is to test the probe's performance. A layer of synthesized gold nanoparticles (AuNPs) and zinc oxide nanoparticles (ZnO-NPs) is used to immobilize this type of SMF-based tapered structure. The work is based on the well-known phenomenon of localized surface plasmon resonance (LSPR) principle. A tapered region of the probe with a high fraction power of evanescent wave can stimulate LSPR and produce specific absorption peaks sensitive to the refractive index variation. The sensor probes performance was examined, including their stability, repeatability, reusability, and selectivity. Furthermore, the biosensor's ability to improve performance was tested in the experiment.
We have fabricated blue organic light-emitting devices (OLEDs) with higher color purity and stability by optimizing the structure of the Glass/ITO/NPB(50 nm)/ BCzVBi (30 nm)/ TPBi (x nm)/Alq3(20 nm)/LiF/Al. The results show that the introducing of hole blocking layer(HBL) TPBi greatly can improve not only the color purity but the color stability, which owe to its higher the Highest Occupied Molecular Orbital (HOMO) energy levels of 6.2 eV. We expect our work will be useful to optimizing the blue OLEDs structure to enhancing the color property.
We experimentally demonstrated a laser diode-pumped Q-switched Nd:GdTaO4 crystal laser at 1066 nm using a multilayer graphene oxide as the saturable absorber (GOSA). The GOSA is fabricated by transferring the liquid-phase-exfoliated GO nanosheets onto a K9 glass substrate. When the GOSA was inserted into the plano–plano laser cavity, a stable Q-switched laser operation is achieved with a maximum average output power of 0.382 W and repetition rate of 362 kHz. The shortest pulse duration is 194 ns and the single pulse energy is about 1.05 μJ.
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