Silicon Photonic Biosensing Techniques for Molecular Detection

Silicon photonic biosensors exploit the mature fabrication methods of complementary metal-oxide semiconductor (CMOS) technology to create compact, high-performance platforms capable of detecting biomolecular interactions in real time. At their core, these systems guide light through microfabricated waveguides and resonant structures, such as microring resonators, where the evanescent field extends beyond the waveguide surface. Binding of target molecules induces minute changes in the local refractive index, producing measurable shifts in resonance wavelength or intensity. High quality factors and narrow linewidths amplify sensitivity, enabling detection limits at the picomolar to femtomolar scale. Integration of arrays of resonators on a single chip permits multiplexed assays, while on-chip light sources, detectors and microfluidic channels further reduce size, cost and sample volume. Advanced approaches combine photonic read-out with electrochemical control to achieve site-selective biofunctionalisation and multiparameter profiling. Collectively, these features promise decentralised diagnostics, environmental monitoring and food safety screening with rapid turnaround, low power consumption and potential for mass production.

Research from Nature Portfolio

Recent studies have introduced an electrophotonic silicon sensor that merges high-Q microring resonators with integrated electrochemical electrodes. By optimally doping the silicon microrings, these devices maintain excellent optical resonance while supporting in situ redox reactions. Electrochemical control permits selective immobilisation of distinct bioreceptors on individual rings, enabling parallel detection of multiple biomarkers. Simultaneous photonic and electrochemical measurements provide complementary information on binding kinetics and chemical reactivity, enhancing quantitative accuracy. This dual-modality approach breaks new ground in multiplexed biomarker profiling on a monolithic silicon chip and paves the way for fully integrated, scalable diagnostic platforms.

Silicon Photonic Biosensing Techniques for Molecular Detection publication trend

The graph below shows the total number of articles in silicon photonic biosensing techniques for molecular detection across all publications each year (not limited to Nature Index journals).

Technical terms

Microring resonator: A closed-loop waveguide that traps light at specific wavelengths, where resonance shifts indicate changes in the surrounding refractive index.

Evanescent field: The decaying electromagnetic field extending outside the waveguide core, which interacts with nearby molecules to enable label-free sensing.

Quality factor (Q): A dimensionless parameter describing the sharpness of resonance; higher Q indicates narrower resonance peaks and greater sensitivity.

Limit of detection (LOD): The smallest concentration of analyte that produces a distinguishable signal above background noise.

Biofunctionalisation: The process of chemically modifying sensor surfaces with biorecognition elements (antibodies, aptamers, peptides) to confer specificity for target molecules.

References

1. Optical Biosensors Based on Silicon-On-Insulator Ring Resonators: A Review. Molecules (2019).
2. The electrophotonic silicon biosensor. Nature Communications (2016).
3. Biosensing with Silicon Nitride Microring Resonators Integrated with an On-Chip Filter Bank Spectrometer. ACS Sensors (2023).
4. A Label-Free Optical Biosensor Based on an Array of Microring Resonators for the Detection of Human Serum Albumin. Sensors (2024).
5. Biofunctionalization of Multiplexed Silicon Photonic Biosensors. Biosensors (2022).