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Optical fiber magnetic field sensor based on birefringence in liquid core optical waveguide
摘要： An optical fiber magnetic field sensor based on the birefringence of magnetic fluid is proposed by filling the magnetic fluid into a hollow-core waveguide. The birefringence characteristics of magnetic fluids with different concentrations tuned by magnetic field were investigated under different magnetic fields when the filled hollow-core waveguide is placed in a Sagnac loop. As the magnetic field increases, the internal chain-like structure of the magnetic fluid increases, resulting in changes in birefringence. The experimental results show that the device has a highly linear response to the variation of magnetic field intensity in the range of 0–300 Oe with the maximum sensitivity of 29.2 pm/Oe and resolution of 0.68 Oe. The proposed magnetic field sensor has such advantages as ease of fabrication, simple structure, low cost and it is expected to find potential applications in the magnetic field measurement with high accuracy, optical fiber gyroscopes, magneto-optic modulators and so on. Due to the external field tunability, the device also provides a promising technology for microfluidics research.
关键词： Birefringence,Optofluidic in fiber,Magnetooptic effects,Optical fiber devices
更新于2025-11-28 14:24:03
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Turbidimetric inhibition immunoassay revisited to enhance its sensitivity via an optofluidic laser
摘要： Turbidimetric inhibition immunoassay (TIIA) is a classic immunodiagnostic method that has been extensively used for biomarker detection. However, the low sensitivity of this technique hinders its applications in the early diagnosis of diseases. Here, a new concept, optofluidic laser TIIA (OFL-TIIA), is proposed and demonstrated for sensitive protein detection. In contrast to the immunoreaction in traditional TIIA, in which the single-pass laser loss is detected, the immunoreaction in the OFL-TIIA method takes place in a laser cavity, which considerably increases the loss induced by antigen-antibody complexes (AACs) via the amplification effect of the laser. A commercial IgG TIIA kit was selected as a demonstrative model to characterize the performance of OFL-TIIA. A wide dynamic range of five orders of magnitude with an exceptional limit of detection (LOD) (1.8×10-10 g/L) was achieved. OFL-TIIA is a fast, sensitive, and low-cost immunoassay with a simple homogeneous and wash-free process and low-volume sample consumption, thus providing a new detection platform for disease diagnostics.
关键词： Biomarker detection,Optofluidic laser,Turbidimetric inhibition immunoassay,Antigen-antibody complexes,Laser dye
更新于2025-11-25 10:30:42
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Replica Symmetry Breaking in a Weakly Scattering Optofluidic Random Laser
摘要： We report the observation of replica symmetry breaking (RSB) in a weakly scattering optofluidic random laser (ORL). Coherent random lasing is indicated by the presence of narrow peaks rising out of the spectral background. This coherence helps to identify a random laser threshold, which is expected to be gradual with weak scattering. We find that lasing action initiated using optical pulsed pumping coincides with the onset of both RSB and Lévy flight statistics. However, the transition from the photonic paramagnetic to photonic glass phase is more subtle in that the Parisi overlap function broadens instead of completely changing shape. This subtlety is balanced by an accompanying result of identical experimental conditions giving rise to lasing or no lasing depending on the shot. Additional statistical calculations and investigations into the fundamental physical mechanisms present in the ORL support this conclusion. Using simple numerical models, we study the critical spectral properties required for RSB to occur, as indicated by the Parisi overlap function. The simplicity of the models helps demonstrate the sensitive nature of this tool and the necessity of additional verification of the physical mechanisms present in the experiment.
关键词： replica symmetry breaking,Lévy flight statistics,Parisi overlap function,optofluidic random laser,mode competition
更新于2025-09-23 15:19:57
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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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DC-biased optofluidic biolaser for uric acid detection
摘要： Optofluidic biolaser is an emerging technology for chemical and biomedical sensing. However, the sensitivity of optofluidic laser is still limited by the laser threshold condition. In this paper we report a DC-biased optofluidic biolaser for uric acid (UA) detection. Inside a Fabry-Perot laser cavity, a coupled enzyme reaction was employed to transform the detection of UA into the detection of analyte-converted hydrogen peroxide (H2O2). The fluorescent product of the enzyme-catalyzed reaction, resorufin, was employed as gain medium for optofluidic lasing. An optimized concentration of H2O2 was pre-added as a DC bias to counterbalance the requirement of high analyte concentration for lasing. UA detection with a limit of detection of 3.63 μM was achieved with a low sample volume as small as 10 μl. This work provides a sensitive technology using optofluidic biolaser for the detection of substance in human body fluids that can be converted into H2O2.
关键词： Optofluidic laser,uric acid,enzyme catalytic reaction,optical biosensing
更新于2025-09-16 10:30:52
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Overview on Monolithically Integrated Arrays of Microtubular Vertical Resonators on Photonic Waveguides for Optofluidic Applications
摘要： A novel platform for optofluidic applications is realized by monolithic integration of an array of ultra-compact three-dimensional (3D) vertically rolled-up microtube ring resonators (VRU-MRRs) with polymer waveguides. The on-chip integrated system is realized by rolling up 2D differentially strained TiO2 nanomembranes into 3D microtubular cavities on a nanophotonic chip. Whispering-gallery modes are observed in the telecom wavelength range, and their spectral peak positions shift significantly when measurements are performed while immersing the tubes or filling their hollow cores with water. The achievement of this work opens up fascinating opportunities to realize massively parallel optofluidic microsystems with exceptional multi-functionality for analysis of biomaterials in lab-in-a-tube systems on a single chip.
关键词： monolithic integration,optofluidic,array of ultra-compact optical sensors,vertically rolled-up microtube ring resonators,3D microcavities
更新于2025-09-16 10:30:52
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On-chip single-mode optofluidic microresonator dye laser sensor
摘要： Optofluidic dye laser devices have great potential as coherent light sources for lab-on-a-chip applications such as sensing and spectroscopy applications, owing to their promising properties as wide wavelength-tunability, proper microfluidic integration, and an extremely miniaturized footprint. The wide emission spectrum of dye molecules and narrow free spectral range of ring resonators, make these lasers inherently multi-mode. In this article, two polydimethylsiloxane-based miniaturized optofluidic ring resonator dye lasers are numerically designed and investigated. First, multi-mode lasing from a single optofluidic ring resonator with a spectral linewidth of 10 nm and a threshold energy density of 2.2 μj/mm2 is demonstrated. Then, by exploiting two coupled optofluidic ring resonators and Vernier effect, single-mode lasing at a center wavelength of 566 nm with a spectral linewidth as small as 5.36×10-4 nm is achieved. Moreover, simulations demonstrate the sensitivity of 500 nm/RIU for the proposed dye laser sensor.
关键词： Optofluidic,Single-mode lasing,Dye laser sensor,Ring resonator
更新于2025-09-16 10:30:52
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A Fast and Reproducible ELISA Laser Platform for Ultrasensitive Protein Quantification
摘要： Optofluidic lasers are currently of high interest for sensitive, intra-cavity, biochemical analysis. In comparison with conventional methods such as fluorescence and colorimetric detection, optofluidic lasers provide a method for amplifying small concentration differences in the gain medium, thus achieving high sensitivity. Here we report the development of an on-chip ELISA (enzyme-linked immunosorbent assay) laser platform that is able to complete an assay in short amount of time with small sample/reagent volumes, large dynamic range, and high sensitivity. The arrayed micro-scale reaction wells in the ELISA lasers can be microfabricated directly on dielectric mirrors, thus significantly improving the quality of the reaction wells and detection reproducibility. The details of the fabrication and characterization of those reaction wells on the mirror are described and the ELISA laser assay protocols are developed. Finally, we applied the ELISA laser to detecting IL-6, showing that a detection limit of about 0.1 pg/mL can be achieved in 1.5 hours with 15 μL of sample/reagents per well. This work pushes the ELISA laser a step closer to solving problems in real-world biochemical analysis.
关键词： Interleukin-6,Fabry-Perot cavity,Immunoassay,Optofluidic laser,Microfabrication,ELISA
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Photoreduction in Optofluidic Hollow-Core Photonic Crystal Fiber
摘要： Optofluidic hollow-core photonic crystal fiber (HC-PCF) uniquely allows light to be guided at the centre of a microfluidic channel. The system maximizes the interaction of light with infiltrated chemicals and (nano)particles, offering unique opportunities for in-situ optical monitoring of a range of photochemical and catalytic reactions [1,2]. Our current goal is to extend this work to hybrid colloidal systems comprising a particulate light absorber and a molecular catalyst for photocatalytic fuel production [3]. Here we use HC-PCF microreactors to study novel light-absorbing particles for such systems: graphitic, N-doped, and amorphous carbon-nanodots (CNDs) that offer a unique combination of scalability, biocompatibility, water solubility, and stable optical properties [4]. To test the CNDs’ absorption- and electron-transfer properties, we combine them with the redox-active heterocycle methyl viologen dichloride (MV2+·2Cl-). Upon absorption of UV light, CNDs can transfer an electron to MV2+, whose reduction to the radical cation (MV?+) creates a strong optical absorption peak around 600 nm (Figs. 1(a,c)). An electron donor (EDTA) is added to the solution to quench the photo-induced holes in the CNDs [4]. The mixture was infiltrated into the core of a 30 cm long liquid-filled kagomé style HC-PCF (Fig. 1(b)), designed to guide in the wavelength range of the MV?+ absorption peak. To ensure a homogeneous excitation of the CNDs, a 5 cm long section of the fiber was side-illuminated by a UV lamp (λ = 365 nm). A supercontinuum source, launched into a guided mode, was used to monitor the absorption spectrum. Despite sample volumes of less than 50 nL, we obtain highly-reproducible time traces of the MV?+ absorption (Fig 1(d-e)). Unexpectedly, a significant initial time-delay of 135 s was observed in the reduction of MV2+, revealing the presence of a previously unknown activation process of the CNDs. The initial delay was found to depend on the functionalization of the CNDs, with delays for a -COOH group (81 s) being ca. three times shorter than those for NH2 (176 s) and NMe2 (204 s) groups. The subsequent reaction rate was found to be independent of the surface-group. Our unexpected results highlight the scope for urgently needed in-situ analysis of photocatalytic systems. Future experiments will include the use of surface-sensitive higher-order modes [5] to selectively probe the diffusion of reaction products within the optofluidic reactor.
关键词： Carbon-Nanodots,Photoreduction,Hollow-Core Photonic Crystal Fiber,Optofluidic,Photocatalytic
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Detection and Tracking of Multiple Individual Nanoparticles in Antiresonant Hollow-Core Fibers
摘要： Directly studying the dynamics of nanoparticles with subwavelength dimensions, for example protein interactions or viral self-assembly, is difficult using conventional light microscopes due to Abbe’s resolution limit. Methods to overcome this limit such as fluorescence microscopy usually require to label particles and suffer from photobleaching in the case of long illumination times. A recent tracking method based on elastic light scattering from nano-objects inside a microstructured fiber which includes a nanometer sized channel managed to circumvent these limitations [1]. However, due to the small channel size, this approach imposes high spatial constraints on the particle motion, impedes the investigation of multi-particle dynamics and allows very little control over the liquid flow inside the fiber. In this work, we demonstrate that antiresonant hollow-core fibers (ARHCFs) open new perspectives for the detection and tracking of unlabeled, individual nanoparticles in statistically large numbers simultaneously. Gold nanospheres of diameters as small as 40nm were introduced into the hollow inner channels of an ARHCF with hexagonally shaped core section of around 30μm in diameter (see Fig. 1a,b). The fiber was integrated into an optofluidic chip system which allows controlling the liquid flow [2], and illuminated by a laser source (wavelength at 532nm). The light scattered off the particles was collected from the transverse direction by a low NA microscope objective (see Fig. 1a) and imaged onto a high speed camera. Applying an appropriate algorithm [3], the obtained data was analyzed and individual particle trajectories deduced (see Fig. 1c). Therefore a single video contains statistical data, e.g. for particle size estimations via the mean squared displacement method for a large number of freely diffusing particles (see Fig. 1d). Since particle tracking for tens of seconds at kHz image rates is possible, this novel method holds strong potential for the investigation of yet unexplored multi-particle dynamics at the nanoscale.
关键词： nanoparticles,antiresonant hollow-core fibers,tracking,detection,optofluidic chip
更新于2025-09-11 14:15:04