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Thin-core fiber-optic biosensor for DNA hybridization detection
摘要： A real-time label-free DNA biosensor based on thin-core fiber (TCF) interferometer is demonstrated experimentally. The proposed biosensor is constructed by splicing a TCF between two segments of single mode fibers (SMFs) and integrated into a microfluidic channel. By modifying the TCF surface with monolayer poly-l-lysine (PLL) and single-stranded deoxyribonucleic acid (ssDNA) probes, the target DNA molecules can be captured in the microfluidic channel. The transmission spectra of the biosensor are measured and theoretically analyzed under different biosensing reaction processes. The results show that the wavelength has a blue-shift with the process of the DNA hybridization. Due to the advantages of low cost, simple operation as well as good detection effect on DNA molecules hybridization, the proposed biosensor has great application prospects in the fields of gene sequencing, medical diagnosis, cancer detection and environmental engineering.
关键词： thin-core fiber,biosensor,microfluidic channel,modal interference,DNA hybridization
更新于2025-11-28 14:23:57
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Fluorescence detection test by black printed circuit board based microfluidic channel for polymerase chain reaction
摘要： This paper proposes the optimal structure of a PCB-based micro PCR chip constructed on a PCB substrate using commercial adhesive tapes and plastic covers. The solder mask of the PCB substrate was coated black, and the area where the reaction chamber is attached was legend printed with white silk to minimize the noise during fluorescence detection. The performance of the PCR and fluorescence detection was compared using 6 types of reaction chambers, each made with different double-sided tapes. Three of the chambers were unsuccessful in completing the PCR. The performance of the other three chambers that successfully amplified DNA was compared using Taqman probe for Chlamydia Trachomatis DNA. The amplified product was illuminated diagonally with a blue LED to excite the product just before imaging, and the LED was turned off when the image was captured to prevent quenching of the probe. The images were taken 10 seconds prior to the last extension step for each cycle using a DSLR camera. The experiments were run as a quartet for each three chambers made with different double-sided tape. The results showed that there were significant difference between the three tapes.
关键词： microfluidic channel,polymerase chain reaction,fluorescence detection test,acrylic adhesive,micro-PCR chip,black PCB,double-sided tape
更新于2025-09-23 15:22:29
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Optofluidic laser speckle image decorrelation analysis for the assessment of red blood cell storage
摘要： Red blood cells (RBCs) undergo irreversible biochemical and morphological changes during storage, contributing to the hemorheological changes of stored RBCs, which causes deterioration of microvascular perfusion in vivo. In this study, a home-built optofluidic system for laser speckle imaging of flowing stored RBCs through a transparent microfluidic channel was employed. The speckle decorrelation time (SDT) provides a quantitative measure of RBC changes, including aggregation in the microchannel. The SDT and relative light transmission intensity of the stored RBCs were monitored for 42 days. In addition, correlations between the decorrelation time, RBC flow speed through the channel, and relative light transmission intensity were obtained. The SDT of stored RBCs increased as the storage duration increased. The SDTs of the RBCs stored for 21 days did not significantly change. However, for the RBCs stored for over 35 days, the SDT increased significantly from 1.26 ± 0.27 ms to 6.12 ± 1.98 ms. In addition, we measured the relative light transmission intensity and RBC flow speed. As the RBC storage time increased, the relative light transmission intensity increased, whereas the RBC flow speed decreased in the microchannel. The optofluidic laser speckle image decorrelation time provides a quantitative measure of assessing the RBC condition during storage. Laser speckle image decorrelation analysis may serve as a convenient assay to monitor the property changes of stored RBCs.
关键词： laser speckle,image decorrelation,microfluidic channel,Optofluidic,RBC aggregation,speckle decorrelation time,red blood cell storage
更新于2025-09-19 17:13:59
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Sensitivity Enhancement of a Concave Shaped Optical Fiber Refractive Index Sensor Covered with Multiple Au Nanowires
摘要： In the present paper, a new kind of concave shaped refractive index sensor (CSRIS) exploiting localized surface plasmon resonance (LSPR) is proposed and numerically optimized. The LSPR effect between polaritons and the core guided mode of designed CSRIS is used to enhance the sensing performance. The sensor is characterized for two types of sensing structures coated with gold (Au) film and Au nanowires (AuNWs), respectively. The influence of structural parameters such as the distance (D) of the concave shaped channel (CSC) from the core, the diameter of the nanowire (dn) and the size (s) of the CSC are investigated here. In comparison to Au film, the AuNWs are shown to significantly enhance the sensitivity and the performance of the designed sensor. An enhanced sensitivity of 4471 nm/RIU (refractive index unit) is obtained with AuNWs, for a wide range of analytes refractive index (na) varying between 1.33 to 1.38. However, for conventional Au film; the sensitivity of 808.57 nm/RIU is obtained for the same range of analytes.
关键词： nanowires,microfluidic channel,surface plasmon resonance,sensitivity,refractive index
更新于2025-09-16 10:30:52