Automatic Irrigation System With Fiber-Optic Pressure Sensor for Real-Time Intrarenal Pressure Control During Instrument Insertion and Laser Irradiation

Machine learning assisted malaria detection using photonic crystal fibre optical sensors.

Abstract This paper proposes a high-sensitivity temperature and nanoscale displacement sensor based on a parallel configuration of dual Fabry-Perot Interferometers (FPIs) and the Harmonic Vernier Effect (HVE), and verifies its performance through experiments. In this experiment, two FPIs were designed and fabricated using single-mode fiber (SMF), ultraviolet (UV) adhesive, capillary tubes, and ceramic ferrules. These two FPIs were connected in parallel to form Sensor S. Among them, FPI 1 is composed of a SMF inserted into a ceramic ferrule. The UV adhesive film coated on the end face of the ceramic ferrule enables FPI 1 to exhibit high sensitivity to temperature, thanks to the significant temperature-responsive property of the UV adhesive material. FPI 2 is composed of two segments of SMF inserted into a quartz capillary tube. By adjusting the axial position of one of the fiber segments, the cavity length can be precisely modified, endowing FPI 2 with exclusive sensitivity to micro-displacement. By setting the cavity lengths of the two FPIs to an approximate 2:1 ratio, the HVE is established. Experimental results show that the sensor achieves a temperature sensitivity of 32.674 nm/℃ and a micro-displacement sensitivity of -0.182 nm/nm, both of which are approximately 15 times those of a single FPI. This sensor enables the independent measurement of the two physical quantities, effectively overcoming the problem of cross-interference between temperature and other physical quantities in traditional optical fiber sensors. In addition, it features a simple fabrication process, solves the parameter matching issue in the conventional Vernier effect, and thus possesses excellent practical value.

Structural health monitoring (SHM) has evolved into an indispensable component for ensuring the safety, durability, and life-cycle efficiency of civil infrastructure. Over the past five years, significant technological advancements have been made in innovative sensing systems, facilitating real-time assessment of structural performance and the early detection of deterioration. This comprehensive review presents recent developments in smart sensor-based SHM, with particular emphasis on the convergence of the Internet of Things (IoT), artificial intelligence (AI), and digital twin (DT) frameworks. Our review critically examines advances in fiber-optic, piezoelectric, MEMS-based, vision-based, acoustic, and environmental sensors, as well as emerging multi-sensor fusion architectures. In addition, bibliometric insights highlight the significant rise in global research activity and influential thematic clusters in SHM between 2020 and 2025. The discussion underscores how AI-integrated data analytics, IoT-enabled wireless networks, and DT-driven virtual replicas enable intelligent, autonomous, and predictive monitoring of bridges, buildings, tunnels, and other large-scale civil infrastructure. Field deployments and case studies are analyzed to bridge the gap between laboratory-scale demonstrations and real-world implementation. Finally, key scientific and practical challenges—including the durability of embedded sensors, the interoperability of heterogeneous data, cybersecurity in connected systems, and the explainability of AI models—are outlined to guide future research. Overall, this review positions contemporary SHM as a transition from traditional damage detection to comprehensive life-cycle management of infrastructure through self-diagnosing, data-centric, and sustainability-driven monitoring ecosystems.

A metamaterial-integrated radio frequency antenna (MTMA), implemented in planar and bend configurations, enables high-resolution MRI of the eye, orbit, and occipital brain at 7.0 T. Its dual-layer co-planar architecture integrates a two-channel transceive loop with a metamaterial layer composed of subwavelength epsilon-negative unit cells. These unit cells were custom-designed based on classical split-ring resonators for operation at 7.0 T. Electromagnetic simulations, including human voxel models, guided the design and characterization of the MTMA's electromagnetic behavior. Both MTMA configurations were benchmarked against conventional loop coil arrays in phantoms and in vivo for experimental validation, demonstrating enhanced transmit (B1 +) efficiency and receive sensitivity enabled by the metamaterial layer through resonant near-field coupling. MRI safety was verified through SAR simulations, bio-thermal modeling, Magnetic Resonance thermometry, and fiber-optic sensors, confirming compliance with safety guidelines. The Bend-MTMA enabled in vivo human MRI of the eye and orbit in healthy volunteers, including B1 + mapping, and provided diagnostic T1- and T2-weighted imaging in volunteers with retinal pathology and sinus cysts, demonstrating clinical applicability. The Planar-MTMA enabled occipital lobe MRI in human volunteers, achieving superior signal coverage and transmit performance. The modular unit cell design enables tuning across MRI magnetic field strengths, establishing a clinically translatable metamaterial-integrated antenna platform for ocular and neurological imaging.

In this work, the photoinduced electron transfer was used as a principle to prepare a series of fiber-optic pH sensors, and the reference sensor was prepared by modifying the functional group and adjusting the film-forming matrix to alter steric hindrance. The pH indicator's sensitivity has been regulated. The surface of the optical fiber was chemically modified with the pH indicator via chemical bonding to enhance the performance of sensor 5. Sensors 5 and 4 formed the ratiometric pH sensor. The experimental results indicated that pH sensitivity can be regulated, and the manufactured sensors are promising for pH detection.

Abstract This study presents a novel approach for uric acid detection using a balloon-like bent polymer optical fiber (POF) sensor. The sensor head was fabricated by integrating an unclad region with macrobending, creating a balloon-like structure that enhances evanescent wave interaction and improves sensing performance. The effect of bending radius on sensor response was systematically investigated, with radii varied from 1.5 to 2.5 cm, to identify optimal conditions. Experimental results revealed a strong linear relationship between transmitted intensity and uric acid concentration of 15-90 mg/dL. Optimal performance was achieved at a bending radius of 1.5 cm and an operating wavelength of 770 nm, delivering a sensitivity of 0.0028 (mg/dL)⁻¹, linearity of 0.8843, and a resolution of 3.61 mg/dL. Compared to other unclad and coated optical fiber designs, the proposed configuration offers a competitive combination of sensitivity, linearity, and detection range while maintaining simple fabrication and robust mechanical properties. These findings highlight the potential of bending geometry optimization as a practical approach to advancing low-cost, high-performance optical fiber biosensors for biomedical and environmental applications.

Abstract Conventional fluorescent fiber optic temperature sensors (FFOS) are widely used in the power industry but exhibit comparatively weak performance at low temperatures. In this study, typical FFOS, operating within a nominal temperature range of −40 to 200 °C, were tested and analyzed. To address the issue of low-temperature measurement inaccuracy, a novel tellurite-tungsten-lanthanum (Te-W-La) glass-based fluorescent material with excellent low-temperature sensing performance was successfully prepared. This was achieved by using tellurite glass as the base material and co-doping it with multiple rare-earth ions ( Er 3 + / Yb 3 + / Pr 3 + ). The results demonstrate that: (1) The traditional FFOS (nominal range −40 to 200 °C) exhibits significant nonlinearity and high measurement randomness below −40 °C, making it difficult to meet measurement requirements in regions below −40 °C. (2) The novel sensor demonstrates outstanding performance across a wide temperature range of −60 to 60 °C. Its sensitivity reaches a peak value of 99 × 10 − 4 / °C at −60 °C, indicating superior low-temperature sensing capabilities. (3) Temperature tests conducted on the new sensing device within the −60 to 60 °C range revealed good repeatability, with deviation values consistently within ±0.5 °C. This data provides a reference for the application and promotion of fluorescent optical fiber sensors in low-temperature regions.

ABSTRACT Advancements in graphene processing have intensified interest in developing efficient plasmonic sensors that exploit the localized surface plasmon resonance (LSPR) phenomena in metallic nanostructures. A streamlined one‐pot synthesis was employed to produce gold nanoparticle‐decorated reduced graphene oxide (RGO/AuNP), eliminating complex multi‐step procedures to achieve an optimized LSPR signal in a tapered multimode fiber optic (TMMF) sensor. Ascorbic acid (AA) of 50 mg, 150 mg, and 250 mg were chosen to avoid further material waste during fabrication. UV‐Vis analysis was shown to determine AuNP spherical size, particle distribution and optical bandgap energy, E g . Increasing mass of AA resulted in smaller average spherical AuNP and was later confirmed by TEM images of RGO/AuNP. The composite reduced with 50 mg AA, which consisted of ~52 nm AuNP size and the lowest E g of 3.36 eV was found to be the most suitable plasmonic coating to be applied on the TMMF sensor because of a stronger plasmonic field and efficient electron transfer. The feasibility of the RGO/AuNP coating was further evaluated based on the quality of LSPR response, optical constants and optical bandgap characteristics. Compared to the layer‐by‐layer composite coating, the one‐pot RGO/AuNP deposited fiber yielded stronger absorbance and narrower FWHM demonstrating its promising potential in fiber optic‐based sensors.

Preliminary results of a fiber optic scour sensor (FOSS) for bridges

Periodic polarization scrambling (PS) has been found to be an effective way of eliminating polarization noises in a pulse-coded Brillouin optical time-domain analysis fiber sensor. It is realized by periodically changing the phase difference between the two orthogonal components of a light. Here, we use phase modulation to generate periodic PS, which utilizes the different modulation efficiencies of the fast and slow axes of a phase modulator. This method not only reduces system complexity but also alleviates the non-local effect compared to our previous approach based on differ-frequency acousto-optic modulation (AOM). Experimental results show that it enhances the signal-to-noise ratio of Brillouin gain by ~4 dB compared to the commonly used random PS. Further, owing to the reduction of the non-local effect, ~4-MHz Brillouin frequency shift measurement error is avoided compared to the AOM-based approach.

Two sensors based on molecularly imprinted polymers and plastic optical fibers for fast and cost-effective MCPA herbicide detection in environmental monitoring.

Fiber-optic photoacoustic sensor for binary gas mixture analysis based on miniaturized integrated dual-frequency-enhanced spectrophone

Fiber-optic hydrophone sensor for passive acoustic monitoring applications

A hybrid demodulation algorithm with high-sensitivity and wide-range for quasi-distributed fiber-optic acoustic sensor

Hybrid plasmonic fiber optic sensor enabling rapid and amplification-free nucleic acid determination for disease screening.

Distributed fiber optic sensors for monitoring cracks in civil infrastructure

A novel embedded optical fibre sensors network and integration strategy for in-situ monitoring of hydrogen storage 70 MPa type IV composite pressure vessels

Dual-mode optical fiber sensor with polydopamine-functionalized surface and PDMS-enhanced temperature compensation for ultrasensitive HCG detection

New calibration method for graphene oxide-coated LPG optical fiber sensors for CO2 detection via symbolic regression