A photonic-microfluidic integrated device for reliable fluorescence detection and counting

Area of Science:

• Optoelectronics
• Microfluidics
• Biophotonics

Background:

• Conventional flow cytometry is limited in point-of-care and remote settings.
• Existing microfluidic devices often require complex optical setups and precise hydrodynamic focusing.

Purpose of the Study:

• To demonstrate a photonic-microfluidic integrated device for reliable fluorescence detection.
• To achieve high-performance detection without relying on 3D hydrodynamic focusing or high-quality laser sources.
• To develop an inexpensive and replaceable device for point-of-care applications.

Main Methods:

• Fabrication of a monolithic planar device integrating microlenses, waveguides, and microfluidic channels.
• Optimization of excitation beam shapes using on-chip optics for specific bead sizes.
• Development of low-cost channel sealing and high-performance interconnecting technology.

Main Results:

• Achieved excellent and reliable fluorescence detection performance with low coefficient of variation (CV) values (8% for 2.5-μm beads, 14% for 6-μm beads).
• Demonstrated reliable detection with relaxed hydrodynamic focusing, ensuring applicability across multiple specimen sizes.
• Identified optimal beam geometry configurations for different bead sizes to maximize detection efficiency.

Conclusions:

• The developed photonic-microfluidic device offers a robust and cost-effective solution for fluorescence detection.
• The device can supplement conventional flow cytometry, particularly in point-of-care and remote diagnostic applications.
• The integrated on-chip optics and optimized beam shaping are key to achieving high performance with simplified fluidics.