Microfabricated polymer chip with integrated U-bend waveguides for evanescent field absorption based detection.

Area of Science:

• Microfluidics
• Optical Sensing
• Analytical Chemistry

Background:

• Microfluidic devices offer miniaturized platforms for chemical analysis.
• Evanescent field absorption and refractive index sensing are label-free detection techniques.
• Integrating optical components within microfluidic systems presents fabrication challenges.

Purpose of the Study:

• To develop and demonstrate a novel micro-total analysis system (µTAS) for label-free detection.
• To explore the use of evanescent field absorption with integrated polymer waveguides.
• To investigate the potential of capillary electrophoresis coupled with this system.

Main Methods:

• Fabrication of a microchannel network with U-bend waveguides using SU-8 photoresist in a single patterning step.
• Optical characterization via absorbance measurements of Methylene Blue dye solutions (450-780 nm).
• Refractive index sensitivity testing using sucrose solutions of varying concentrations.

Main Results:

• Successful integration of microchannels and U-bend waveguides within a single SU-8 layer.
• Demonstrated optical application suitability through absorbance measurements.
• Confirmed sensitivity to fluid refractive index changes.

Conclusions:

• The developed µTAS with integrated waveguides is suitable for label-free molecular detection.
• The system can utilize both evanescent wave absorption and refractive index changes for sensing.
• This novel design facilitates label-free analysis in microfluidic systems.