Graphene-based optofluidic tweezers for refractive-index and size-based nanoparticle sorting, manipulation, and...

Area of Science:

• Nanotechnology
• Biophysics
• Optics

Background:

• Accurate manipulation and sorting of nanoscale bio-particles are crucial for diagnostics and research.
• Existing methods often face limitations in precision and versatility for sub-2.5 nm particles.
• Optofluidic systems offer promising avenues for label-free manipulation.

Purpose of the Study:

• To propose and numerically investigate a novel graphene nanoribbon-based optofluidic tweezer system.
• To demonstrate the capability of manipulating and sorting bio-particles with radii below 2.5 nm.
• To explore the tunability of the system for size- and refractive index-based separation.

Main Methods:

• Numerical investigation using the finite difference time domain (FDTD) method and Maxwell's stress tensor analysis (MST).
• Finite element method (FEM) for electrostatic response analysis.
• Design incorporates graphene nanoribbons, microfluidic channels, and an hBN layer on a Si substrate.

Main Results:

• Achieved intense hotspots with electric field enhancements up to 900x.
• Demonstrated size-based separation by adjusting gap distance and guiding particles into sub-channels.
• Showcased tunable sorting based on graphene's chemical potential (Fermi level) via gate voltage.
• Confirmed sorting capability based on particle refractive indices.

Conclusions:

• The proposed optofluidic tweezer effectively manipulates and sorts nanoscale bio-particles.
• Tunable sorting based on size and refractive index is achievable by adjusting graphene's Fermi level.
• The system holds potential for detecting and analyzing tiny bio-particles like viruses and cancer cells.