Microfluidic In Situ Patterning of Silver Nanoparticles for Surface-Enhanced Raman Spectroscopic Sensing of...

Area of Science:

• Nanotechnology
• Microfluidics
• Biosensing

Background:

• Microfluidic devices offer precise control for chemical synthesis, particularly for metallic nanoparticles used in surface-enhanced Raman spectroscopy (SERS).
• Understanding microscale reactions is crucial for exploiting microsystems in biosensing through controlled nanomaterial synthesis.

Purpose of the Study:

• To investigate the impact of microfluidic geometry on nanoparticle patterning for high-resolution SERS-based sensing.
• To develop a microfluidic system for uniform *in situ* nanoparticle patterning, enhanced mixing, and rapid room-temperature reactions.

Main Methods:

• Systematic study of microchannel geometry's role in nanoparticle patterning.
• Fabrication and testing of a spiral-shaped microchannel for *in situ* synthesis and patterning.
• Demonstration of label-free detection of rhodamine B and a DNA sequence using SERS.

Main Results:

• A spiral microchannel design enhances mixing and enables rapid, room-temperature nanoparticle synthesis and uniform patterning.
• Achieved high enhancement factors for SERS detection: ~4.3 × 10^11 for 1 pM rhodamine B and ~1.5 × 10^8 for 1 nM DNA.
• Demonstrated the system's capability for label-free, on-chip detection of biomolecules.

Conclusions:

• Microfluidic geometry is a key parameter for rational design of continuous microfluidic systems for SERS applications.
• The integrated system provides a facile strategy for fabricating SERS-active substrates.
• Promotes system integration, miniaturization, and on-site biological applications for advanced biosensing.