Label-free terahertz microfluidic biosensor for sensitive DNA detection using graphene-metasurface hybrid structures

Area of Science:

• Terahertz (THz) spectroscopy
• Nanomaterials
• Biosensing
• Microfluidics

Background:

• Terahertz (THz) biosensors offer label-free detection but struggle with sensitivity for absorptive liquid samples.
• Metasurfaces enhance THz wave interaction, but integration with microfluidics for liquid samples remains challenging.

Purpose of the Study:

• To develop a highly sensitive THz biosensor for liquid samples by integrating graphene with a THz metasurface in a microfluidic cell.
• To demonstrate the enhanced sensing performance of the hybrid platform compared to conventional microfluidic devices.
• To validate the platform's capability for specific biomolecule detection, including pathogen DNA.

Main Methods:

• Fabrication of a microfluidic cell incorporating a graphene-enhanced THz metasurface.
• Comparative analysis of sensing performance using pure microfluidic, metasurface-only, and graphene-only microfluidic cells.
• Modification of the graphene-metasurface with aptamers for specific DNA sequence recognition.
• Real-time, label-free detection of DNA sequences using THz transmission measurements.

Main Results:

• The graphene-metasurface microfluidic platform significantly enhances sensitivity for THz biosensing in liquids.
• Comparative experiments confirmed the superiority of the hybrid design over individual components.
• Successful detection of 100 nM DNA short sequences specific to Escherichia coli O157:H7 was achieved.
• The platform demonstrated high sensitivity, label-free operation, and reusability.

Conclusions:

• The proposed THz graphene-metasurface microfluidic biosensor offers a promising platform for sensitive, real-time, and label-free detection of biomolecules in liquid environments.
• This hybrid nanomaterial-metasurface approach opens new avenues for advanced THz biosensing applications.
• The platform's advantages include low cost, ease of use, and reusability, making it suitable for various diagnostic and monitoring tasks.