Pedestal High-Contrast Gratings for Biosensing.

Area of Science:

• Photonics
• Nanotechnology
• Biomedical Engineering

Background:

• High-contrast gratings (HCG) are effective for label-free biomarker detection due to sharp optical resonances.
• Conventional HCG designs have limitations in sensitivity and detection capabilities.

Purpose of the Study:

• To experimentally evaluate the performance of pedestal HCG (PHCG) for biosensing.
• To compare the sensitivity and detection limits of PHCG with conventional HCG.

Main Methods:

• Fabrication and characterization of pedestal HCG (PHCG) and conventional HCG.
• Measurement of bulk refractive index sensitivity and surface sensitivity using model analyte layers (Al2O3, HfO2, TiO2).
• Avidin-biotin binding assay in solution to determine limit of detection (LoD) and limit of quantification (LoQ).

Main Results:

• PHCG exhibited an 11.2% improvement in bulk refractive index sensitivity (536 nm/RIU vs. 482 nm/RIU).
• PHCG showed a 10.5% improvement in surface sensitivity.
• PHCG achieved a lower limit of detection (LoD) of 2.1 ng/mL and limit of quantification (LoQ) of 85 ng/mL for avidin detection, compared to conventional HCG (LoD: 3.2 ng/mL, LoQ: 213 ng/mL).

Conclusions:

• Pedestal HCG demonstrates significantly enhanced performance for label-free biosensing.
• The improved sensitivity and lower detection limits of PHCG make it highly suitable for detecting low analyte concentrations.
• PHCG holds great potential for advanced biosensing applications.