Intensity-Based Camera Setup for Refractometric and Biomolecular Sensing with a Photonic Crystal Microfluidic Chip

Area of Science:

• Optoelectronics
• Biomedical Engineering
• Nanotechnology

Background:

• Label-free sensing is crucial for point-of-care testing.
• Photonic crystal slabs (PCSs) offer a versatile platform for label-free biosensing.
• Intensity-based camera setups (IBCSs) provide advantages but have performance limitations.

Purpose of the Study:

• To enhance the sensitivity and limit of detection (LOD) of PCS-based IBCSs.
• To optimize the system response using a sharp-edged cut-off filter.
• To demonstrate the practical application of the improved system for biosensing.

Main Methods:

• Implemented a sharp-edged cut-off filter with a PCS-based IBCS.
• Fabricated a biochip integrating microfluidics and PCS.
• Analyzed performance using refractive index steps and biosensing assays.

Main Results:

• Achieved a significant improvement in LOD from (7.1 ± 1.3) × 10^-4 RIU to (3.2 ± 0.7) × 10^-5 RIU.
• Demonstrated autonomous transport on the microfluidic biochip.
• Successfully detected various biomolecules including antibodies, streptavidin, and IgG from whole blood.

Conclusions:

• The optimized IBCS with a cut-off filter offers enhanced performance for label-free biosensing.
• The developed biochip platform shows potential for sensitive and specific point-of-care diagnostics.
• Spatial information and speed of detection are key advantages for real-world applications.