Fourier spotting: a novel setup for single-color reflectometry

Area of Science:

• Optical biosensing
• Label-free bioanalysis
• Surface plasmon resonance

Background:

• Single-color reflectometry is a sensitive optical biosensor technique.
• Existing methods can suffer from baseline offset and drift.
• Label-free detection is crucial for real-time bioanalysis.

Purpose of the Study:

• To present a novel single-color reflectometry setup using differential Fourier spotting.
• To demonstrate its capability for label-free detection and kinetic analysis.
• To reduce baseline offset and drift in optical biosensing.

Main Methods:

• Utilized patented micro-mirror technology for signal encoding.
• Employed a single photodiode for simultaneous analyte and reference channel detection.
• Implemented a 180° phase shift for baseline offset reduction.

Main Results:

• Achieved detection of refractive index changes as low as Δn < 0.01.
• Validated heterogeneous binding interaction detection (antibody/antigen).
• Determined binding kinetics with an affinity constant K_A = 1.59 × 10^-7 M^-1.

Conclusions:

• The differential Fourier spotting setup is effective for reliable bioanalysis.
• The system offers robust and sensitive label-free detection.
• This technology advances optical biosensor capabilities.