Chip-based digital surface plasmon resonance sensing platform for ultrasensitive biomolecular detection.

Area of Science:

• Nanotechnology
• Plasmonics
• Biosensing

Background:

• Conventional analog surface plasmon resonance (SPR) sensors face limitations in sensitivity and dynamic range for detecting ultralow analyte concentrations.
• There is a need for low-cost, rapid fabrication methods for high-performance sensing platforms.

Purpose of the Study:

• To present a chip-based ultrasensitive SPR sensor utilizing a checkerboard nanostructure for digital detection.
• To demonstrate enhanced sensitivity and a wider dynamic range compared to conventional SPR methods.
• To enable the detection of ultralow analyte concentrations with improved accuracy.

Main Methods:

• Fabrication of silver-capped nanoslit arrays on plastic substrates using thermal-embossing nanoimprint.
• Optimization of nanoslit arrays to generate sharp Fano resonances for high sensitivity.
• Implementation of a checkerboard pattern for optical isolation and reduced crosstalk between sensing elements.

Main Results:

• Achieved high-intensity sensitivity of 20,000% per refractive index unit with 12.5µm sensing elements.
• Demonstrated digital detection limit of 1pg/mL for protein-antibody experiments, 1000 times lower than analog detection.
• Exhibited a dynamic range 100 times higher than conventional SPR for a 140µm×140µm checkerboard pattern.
• Achieved crosstalk lower than 1% due to polarization-dependent transmission.

Conclusions:

• The developed checkerboard nanostructure SPR sensor offers ultrasensitive digital detection capabilities.
• This technology is highly effective for detecting ultralow concentrations of analytes, even with nonuniform distribution.
• The low-cost, rapid fabrication method makes this sensor platform suitable for various applications requiring high-performance biosensing.