A Versatile Platform with Expanding Applications
What the Past Decade Has Delivered
Persistent Technical and Practical Barriers
Scaling Up
Optical fiber biosensors (OFBs) have advanced rapidly over the past decade, reaching ultra-low detection limits for biomarkers, pathogens, and environmental toxins through stronger light–matter interactions and increasingly sophisticated fiber designs.
Even so, issues around reproducibility, multiplexing, and scalable manufacturing continue to limit their transition from research prototypes to widely deployed clinical and field-ready diagnostic systems. A recent article in Advanced Photonics reviews the most significant progress in light–matter interaction-based OFBs and outlines the work still ahead.
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OFBs are widely regarded as a flexible and highly sensitive sensing platform. They are implemented in several configurations, including fiber Bragg gratings (FBGs), interferometric designs, and D-shaped fibers that often rely on surface plasmon resonance (SPR). These structural variations allow sensors to be tailored to specific analytes, supporting applications across biomedical diagnostics, environmental monitoring, and chemical analysis.
Despite meaningful technical progress, practical hurdles remain. Repeatability, effective multiplexing, and complex data interpretation continue to slow clinical and commercial adoption. Recent efforts aim to address these constraints by integrating artificial intelligence algorithms for improved signal processing and by developing advanced materials that enhance both sensitivity and the reliability of surface functionalization.
A key strength of OFBs lies in their ability to enable label-free, real-time detection in many configurations, supported by precise surface chemistry. Their compact size, compatibility with low sample volumes, and multiplexing potential make them attractive alternatives to commercial diagnostic tools, particularly in scenarios where optical sensing offers clear advantages over electrochemical or traditional analytical methods.
As the demand for accurate, real-time, and multi-analyte detection grows, OFBs are gaining attention as enabling components in personalized and intelligent diagnostic systems aligned with Healthcare 5.0. However, improvements in reproducibility, manufacturing scalability, and standardization remain essential before widespread clinical deployment becomes feasible.
What the Past Decade Has Delivered
The review organizes major OFB approaches and their applications over the past ten years. Core sensor types include interferometer-based designs, FBGs, D-shaped and microstructured fibers, and lossy mode sensors. Each offers distinct advantages depending on the target analyte and operating environment.
At their core, these sensors translate local refractive index (RI) changes into measurable shifts in light propagation, often leveraging evanescent field interactions. Fabrication techniques such as tapering, using arc-fusion splicers or flame-brush methods, enable the creation of thin fibers with very small diameters and taper ratios exceeding 20.8. Refractive index calibration is typically performed stepwise within the 1.33–1.35 range, corresponding to biological fluids such as serum and urine.
Sensors are also categorized according to their target molecules, many of which serve as biomarkers for cardio-metabolic and neurological disorders, cancer, infectious diseases, or environmental contaminants. Key bioparticle classes include pathogens, genetic materials, cancer biomarkers, and environmental pollutants.
Application examples highlight the technology’s sensitivity. Heavy metal detection using Fabry–Pérot interferometers (FPI) and microstructured sensors has achieved detection limits as low as 0.49 ppb for lead ions and 0.9 fM in specific configurations. These results illustrate the technical capabilities of optical fiber systems, while also underscoring that performance varies significantly with fiber architecture, functionalization strategy, and sensing modality.
Persistent Technical and Practical Barriers
Despite steady progress, several challenges continue to limit real-world adoption. Certain optical fiber gratings exhibit inherently low sensitivity, and some configurations struggle with poor repeatability and temperature cross-sensitivity. Interferometers and SPR-based systems, while powerful, are often complex and costly to manufacture.
In practical environments, OFBs must contend with interference from ambient light, background absorbance, fluorescence, and intrinsic Raman scattering within the fiber itself. Environmental variable, particularly temperature and pH, can significantly affect measurement stability and reproducibility. Because refractive index is temperature-dependent, fiber gratings, interferometers, and SPR devices may experience resonant wavelength shifts or altered resonance conditions, reducing accuracy.
Addressing temperature cross-sensitivity requires thoughtful sensor design, reference channels, and advanced signal processing strategies. Material-related challenges add another layer of complexity. Biomolecules immobilized on fiber surfaces can degrade over time, preparation methods may lack uniformity, and micro- and nanofabrication processes often involve harsh conditions.
SPR-based OFBs are particularly sensitive to environmental fluctuations, as their functionalized biomolecules can denature during storage or transport, limiting shelf life. Moreover, surface modification procedures remain largely manual, making automation and cost-effective mass production difficult. This lack of manufacturing standardization directly affects repeatability.
Finally, most current OFBs are designed for single-analyte detection. However, market demand increasingly favors versatile, cost-effective systems capable of simultaneously detecting multiple targets with high specificity and sensitivity. Achieving this balance remains one of the most important and technically demanding goals for next-generation devices.
Scaling Up
Emerging manufacturing strategies offer reasons for optimism. The use of commercial 3D-printed filaments, for example, provides low-cost and rapidly fabricated alternatives to conventional platforms. These approaches can deliver comparable performance while enabling scalable and reproducible production of sensing probes and microfluidic components for point-of-care testing (POCT).
Multiplexed biosensors represent another critical direction. Simultaneous multi-analyte detection requires careful management of cross-reactivity and increasingly complex signal interpretation, areas where AI and machine learning tools are beginning to play a meaningful role.
Integration with wearable systems and the Internet of Things (IoT) further expands the application landscape. Coupled with wireless communication and cloud-based analytics, OFBs could support continuous, high-precision health monitoring. This convergence aligns with Healthcare 5.0 models that emphasize intelligent, connected, and patient-centered diagnostics.
For OFBs to reach their full potential, future systems must balance cost-effectiveness, simple calibration, low detection limits, and fast response times with durable reproducibility, long-term stability, and compatibility with scalable manufacturing processes. The scientific foundation is strong; translating that foundation into robust, real-world solutions is the next step.
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