RESUMEN
Microplastic (MP) residues in marine have become an increasingly serious environmental pollution issue, and in recent years the detection of MPs in marine started to attract worldwide research interests. Optical-fiber-based environmental sensors have been extensively employed for their several merits such as high sensitivity, pressure resistance, compactness and ease of constructing communication networks. However, fiber-optic refractive index sensors are not specifically developed for distinguishing MPs from other inorganic particles suspended in water. In this paper, an metal-organic framework (MOF) ZIF-8 functionalized S-tapered fiber (STF) sensor is proposed for specific detection of polystyrene nanoplastics (PSNPs) in aqueous environment. ZIF-8 coordination nanoporous polymers with different film thickness were immobilized over the surface of the fabricated STF structure based on self-growth technique and yielding a large surface area over the sensor surface. High sensitivity detection can be achieved by converting the concentration perturbation of PSNPs into evanescent waves over the ZIF-8 functionalized STF surface through the strong electrostatic adsorption effect and π-π stacking, while the fabricated sensor is insensitive to gravels with silica as the primary component in water. It is found that the proposed detector with 18 film layers achieves a sensitivity up to 114.1353nm/%(w/v) for the PSNPs concentration range of 0.01 %(w/v) to 0.08 %(w/v).
RESUMEN
A real-time label-free lateral offset spliced coreless fiber (CF) Mach-Zehnder interferometer (MZI) biosensor functionalized with hydrophobin Grifola frondosa I (HGFI) was proposed for the detection of cytokine tumour necrosis factor alpha (TNF-α). The nanolayer self-assembled on the optical fiber surfaces by HGFI rendered the immobilization of probe TNF-α antibody and recognition of antigen TNF-α. Trifluoroacetic acid was utilized to remove the HGFI layer from the glass surface, which was validated by field emission scanning electron microscopy (FESEM) and water contact angle (WCA). Results demonstrated that the processes of HGFI modification, antibody immobilization and specific antibody detection can be monitored in real time. The proposed biosensor exhibited good specificity, repeatability and low detection limit for TNF-α, extending its application in inflammation and disease monitoring.
RESUMEN
A new type of cascaded taper integrated ultra-long-period fiber grating (ULPFG) based immunobiologic sensor has been developed that benefits from the self-assembled monolayer of class I hydrophobin HGFI. Due to the cascaded arc, discharge tapers constitute an ultra-long-period and circular symmetrical refractive index modulation along fiber axial direction, and by local integration in one period, the mode coupling would generate to the higher harmonic of LP02, LP03 and LP04 modes in the wavelength range from 1300â nm to 1620â nm. The hydrophobic characteristic of the ULPFG surface is modified employing the HGFI, and the antibody molecule probes could be absorbed strongly on the HGFI nano-film, furthermore, the performances of immunobiologic sensing are investigated employing multiple control groups of matched and mismatched antigen molecule targets. The results show that it possesses higher sensing sensitivity of 4.5â nm/(µg/ml), faster response time about of 35 min, lower stability error of 8.8%, and excellent immuno-specificity. Moreover, this proposed ULPFG sensor has the advantages of low cost, simple fabrication and label-free, which is a powerful tool in the trace biomedical detection field.
RESUMEN
In this study, a high-sensitivity intensity-interrogated fiber sensor integrated with ferrofluids is proposed for the measurement of a weak magnetic field (MF) with resolved temperature cross-sensitivity. The MF sensor is fabricated simply by an offset tapering single-mode fiber concatenated with a multimode fiber (MMF), which is then encapsulated into a capillary tube filled with ferrofluids. In the presence of MMF, stronger mode coupling could be achieved over the S-tapered fiber region. Its spectral response to variations in the applied MF intensity and ambient temperature have been investigated in detail. The proposed sensor shows a high MF sensitivity up to -0.1130dB/Oe for the measurement range of 40 to 120 Oe, which, to our best knowledge, is higher than other previously reported MF sensors. And moreover, the measurement errors caused by temperature cross-sensitivity have been corrected by using a sensing matrix for the temperature range of 25°C to 35°C. Our proposed MF sensor possesses the advantages of high sensitivity, low cost, and applicability for applications in weak MF measurements.
