Label-free biosensing using a photonic crystal structure in a total-internal-reflection geometry

Area of Science:

• Optoelectronics
• Nanotechnology
• Biomedical Engineering

Background:

• Label-free biosensing is crucial for real-time monitoring of biomolecular interactions.
• Existing technologies like surface plasmon resonance (SPR) have limitations in sensitivity and accuracy.
• Developing novel optical biosensors is essential for advancing diagnostics and research.

Purpose of the Study:

• To present and investigate a novel optical biosensor utilizing a one-dimensional photonic crystal structure in a total-internal-reflection (PC-TIR) geometry.
• To demonstrate the sensor's capability for label-free, highly sensitive detection of analytes and refractive index changes.
• To compare the performance of the PC-TIR sensor with state-of-the-art surface-plasmon-resonance (SPR) systems.

Main Methods:

• Fabrication of a one-dimensional photonic crystal structure integrated with a total-internal-reflection setup.
• Formation of a micro Fabry-Perot resonator for narrow optical resonance.
• Utilizing an open sensing surface for real-time biomolecular binding detection.
• Measuring spectral shifts and intensity ratio changes in differential reflectance for quantification.

Main Results:

• The PC-TIR sensor demonstrated high sensitivity for bulk solvent refractive index changes (7x10⁻⁸ RIU).
• Detection limits for molecular layer thickness (6x10⁻⁵ nm) and mass density (24 fg/mm²) were achieved.
• Experimental results showed significant improvements compared to SPR-based systems.
• Real-time biomolecular binding events were accurately detected.

Conclusions:

• The developed PC-TIR biosensor is a promising technology platform for high-sensitivity and accurate biomolecular detection.
• The sensor's simple configuration and superior performance make it suitable for various biosensing applications.
• This technology offers a significant advancement over existing label-free biosensing methods.