Compact fluorescence detection using in-fiber microchannels-its potential for lab-on-a-chip applications

Area of Science:

• Optoelectronics
• Chemical Sensing
• Microfluidics

Background:

• Fiber optic sensors offer miniaturization and remote sensing capabilities.
• Microfluidic integration enhances sensitivity and reduces sample volume.
• Developing compact and efficient fluorescence sensors is crucial for various analytical applications.

Purpose of the Study:

• To develop and characterize a compact fluorescence sensor utilizing an in-fiber microchannel.
• To evaluate the sensor's sensitivity, reproducibility, and performance using different fiber materials.
• To explore the potential for integrating this sensor into lab-on-a-chip systems.

Main Methods:

• Fabrication of in-fiber microchannels (100 µm width, 210 µm depth) using a CO(2) laser.
• Utilizing a blue LED as the excitation source, a multimode fiber (PMMA or silica) as the light guide, and a mini-PMT as the detector.
• Testing the sensor's performance with fluorescein in phosphate-buffered saline (PBS) solution.

Main Results:

• Achieved high sensitivity, detecting fluorescein down to 0.005 µg/L.
• Demonstrated reproducible measurements.
• Silica fiber sensor exhibited superior sensitivity compared to the PMMA fiber sensor, potentially due to fouling in PMMA.

Conclusions:

• The developed in-fiber microchannel fluorescence sensor is compact, practical, and highly sensitive.
• Silica fiber offers better performance than PMMA fiber for this application.
• The sensor shows significant potential for integration into microfluidic chips for lab-on-a-chip applications.