Optical Fiber Nanoprobes for Biological Sensing Applications

Optical fiber nanoprobes merge the flexibility and remote‐access capability of fibre optics with nanoscale functional structures to achieve highly sensitive, minimally invasive detection of biological analytes. By integrating plasmonic or photonic nanostructures on the distal tip of an optical fibre, these devices exploit enhanced light–matter interactions—such as localised surface plasmon resonance and surface-enhanced Raman scattering—to detect proteins, nucleic acids, small molecules and even whole cells in complex environments. Fabrication approaches range from top-down techniques such as focused ion beam milling and two-photon polymerisation to bottom-up self-assembly methods and nanosphere lithography. Key advantages include point-of-care compatibility, in vivo operation through needle-scale probes, rapid real-time readout and the capacity to tune sensitivity, dynamic range and specificity through nanoscale design. Collectively, these innovations are driving a new generation of plug-and-play lab-on-fiber platforms for diagnostics, therapeutic monitoring and environmental surveillance.

Research from Nature Portfolio

Recent studies have demonstrated self-assembled plasmonic nanohole arrays on multimode fibre facets, yielding distinct reflection dips and strong near-field enhancement for label-free protein binding assays. The large facet area and high numerical aperture optimise light coupling, while real-time monitoring of specific biomolecular interactions underscores the potential for portable biosensing systems. In parallel, microgel-assisted lab-on-fiber optrodes have been realised by integrating stimulus-responsive polymer networks directly onto a resonant plasmonic nanostructure at the fibre tip. The microgel concentrates target molecules within its network, amplifies the optical response and allows tunable limits of detection, response times and working ranges by adjusting microgel composition and operating temperature. Foundational work on direct focused ion beam milling has provided the template for these advances by enabling the fabrication of sub-wavelength photonic crystal slabs on fibre facets. Successive deposition of high-index or metallic layers on the milled template produces guided resonances or hybrid photonic–plasmonic modes, offering a versatile route to engineer spectral response and field distribution for future lab-on-fiber devices.

Optical Fiber Nanoprobes for Biological Sensing Applications publication trend

The graph below shows the total number of articles in optical fiber nanoprobes for biological sensing applications across all publications each year (not limited to Nature Index journals).

Technical terms

Surface-Enhanced Raman Scattering (SERS): A spectroscopic technique in which Raman scattering signals are greatly amplified by plasmonic nanostructures, enabling ultra-sensitive molecular detection.

Localised Surface Plason Resonance (LSPR): The resonant oscillation of conduction electrons confined to metallic nanostructures, highly sensitive to local refractive index changes.

Lab-on-Fiber: A miniaturised platform in which multiple analytical functions are integrated directly onto or within an optical fibre, enabling compact, multifunctional sensing probes.

Focused Ion Beam (FIB) Milling: A top-down nanofabrication method that uses a focussed beam of ions to remove or shape material with sub-100-nm precision on fibre facets.

Microgel: A cross-linked polymer network that swells in aqueous environments, capable of concentrating target biomolecules and modulating sensing performance.

References

1. SERS assisted sandwich immunoassay platforms for ultrasensitive and selective detection of human Thyroglobulin. Biosensors and Bioelectronics (2023).
2. Plasmonic Biosensor on the End-Facet of a Dual-Core Single-Mode Optical Fiber. Biosensors (2023).
3. Nanosphere Lithography on Fiber: Towards Engineered Lab-On-Fiber SERS Optrodes. Sensors (2018).
4. Fiber‐Optic SERS Probes Fabricated Using Two‐Photon Polymerization For Rapid Detection of Bacteria. Advanced Optical Materials (2020).
5. Optical fiber tip templating using direct focused ion beam milling. Scientific Reports (2015).
6. Lab-On-Fiber Technology: A Roadmap toward Multifunctional Plug and Play Platforms. Sensors (2020).
7. A self-assembled plasmonic optical fiber nanoprobe for label-free biosensing. Scientific Reports (2019).
8. Microgel assisted Lab-on-Fiber Optrode. Scientific Reports (2017).