Sub-micrometric reflectometry for localized label-free biosensing.

Area of Science:

• Optics and Photonics
• Biotechnology
• Materials Science

Background:

• Characterizing sub-micrometric areas is crucial for advanced applications like biosensing.
• Existing techniques may lack the resolution or specificity for analyzing micro-scale interactions.
• Developing novel optical methods is essential for improving sensitivity and spatial resolution in bio-assays.

Purpose of the Study:

• To present a new optical technique for characterizing sub-micrometric areas based on light reflectivity.
• To fabricate and evaluate Bio Photonic Sensing Cells (BICELLs) for biosensing applications.
• To compare the performance of the developed technique with existing methods like FT-VIS-NIR spectrometry.

Main Methods:

• Utilized an optical technique measuring light reflectivity as a function of angle of incidence for s and p polarizations.
• Characterized circular areas with diameters around 600 nm with high angular resolution (0.1°).
• Fabricated Bio Photonic Sensing Cells (BICELLs) using SU-8 polymer interferometers on silicon substrates and performed indirect immunoassays.

Main Results:

• Successfully characterized sub-micrometric areas with high resolution and obtained polarization-dependent spectra in a single measurement.
• Demonstrated the efficacy of BICELLs for biosensing through indirect immunoassay.
• Achieved a Limit of Detection (LoD) comparable to high-resolution spectrometry for immunoassays on sensing surfaces.

Conclusions:

• The presented optical technique offers a powerful tool for analyzing sub-micrometric domains with high resolution.
• BICELLs integrated with this technique provide a sensitive platform for biosensing and immunoassays.
• This approach enables localized analysis of bio-reactions on sensing surfaces, complementing traditional spectrometry.