Composite Sensor Particles for Tuned SERS Sensing: Microfluidic Synthesis, Properties and Applications

Area of Science:

• Microfluidics and Nanotechnology
• Materials Science
• Analytical Chemistry

Background:

• Surface-enhanced Raman scattering (SERS) offers potent particle-based sensing capabilities.
• Droplet-based microfluidics enable precise control over micro- and nanoparticle size and composition.
• Achieving homogeneous sensor particles is critical for reliable SERS sensing, but current methods often yield larger particles.

Purpose of the Study:

• To develop a microfluidic approach for generating small, homogeneous polymer microparticles with embedded silver nanoparticles.
• To investigate the synthesis of composite microparticles for SERS sensing applications.
• To explore the impact of particle size and analyte concentration on SERS sensing performance.

Main Methods:

• Utilized a unique micro cross-flow arrangement for generating polymer microparticles (30–600 μm) with in situ embedded silver nanoparticles.
• Employed silver-catalyzed silver deposition for enhanced silver coverage on microparticles.
• Investigated SERS sensing of biochemical molecules (amino acids, vitamins) using the synthesized composite microparticles.

Main Results:

• Successfully generated polymer microparticles with a broad size range and homogeneous distribution of silver nanoparticles.
• Demonstrated effective silver nanoparticle enforcement for enhanced SERS activity.
• Analyzed the influence of analyte concentration and microparticle size on SERS sensing sensitivity and homogeneity.

Conclusions:

• The developed microfluidic platform enables size-tuned droplet generation and synthesis of composite microparticles for SERS sensing.
• Synchronized photopolymerization and photoreduction mechanisms contribute to the creation of effective SERS sensor particles.
• The study provides a systematic investigation into the optimization of SERS sensing using tailored composite microparticles.