Scattering detection using a photonic-microfluidic integrated device with on-chip collection capabilities

Area of Science:

• Photonics
• Microfluidics
• Optical Detection

Background:

• Photonic-microfluidic integrated devices are crucial for advanced sensing applications.
• On-chip beam shaping and collection are key to improving detection sensitivity and reliability.
• Scattering detection and counting applications require precise control over optical parameters.

Purpose of the Study:

• To demonstrate SU-8-based photonic-microfluidic devices with on-chip beam shaping and collection.
• To evaluate the performance of these devices in scattering detection and counting applications.
• To assess the impact of on-chip beam geometry and bead size on detection CV values.

Main Methods:

• Fabrication of SU-8-based photonic-microfluidic devices with integrated excitation optics.
• Utilizing tailored beam geometries for scattering detection of micro-beads.
• Employing both free-space and on-chip optical waveguide collection schemes.
• Analyzing device performance using coefficient of variation (CV) and coincident rates.

Main Results:

• Excellent CV values (11.0-16.4%) achieved for 1-5 μm blank beads with free-space detection.
• Demonstrated ability to resolve mixed populations of 2.0 and 5.0 μm beads with low CVs (15.9% and 18.5%).
• On-chip collection via optical waveguides yielded a high coincident rate of 94.2% compared to free-space collection.
• Achieved a CV of 19.2% for 5 μm beads using on-chip excitation and collection with a 6.0-μm beam waist.

Conclusions:

• SU-8-based photonic-microfluidic devices enable effective scattering detection and counting with on-chip beam shaping.
• Device performance is significantly influenced by the interplay between on-chip beam geometry and bead size.
• On-chip optical waveguide collection offers superior reliability over free-space methods for these integrated devices.