On-chip cavity-enhanced absorption spectroscopy using a white light-emitting diode and polymer mirrors

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Microfluidics

Background:

• Cavity-enhanced spectroscopy offers high sensitivity but often requires complex setups.
• Microfluidic devices enable miniaturized and portable analytical systems.
• Integrating optical cavities into microfluidic chips presents a challenge for enhancing sensitivity in compact formats.

Purpose of the Study:

• To develop a disposable microfluidic chip with integrated cavity mirrors.
• To enhance the performance of cavity-enhanced absorption spectroscopy (CEAS) using a white light-emitting diode (LED).
• To achieve low detection limits in a miniaturized optical path length.

Main Methods:

• Fabrication of a disposable microfluidic chip incorporating cavity mirrors made from 3M Vikuiti™ enhanced specular reflector II (ESRII) film.
• Performance evaluation of the chip using cavity-enhanced absorption spectroscopy with a white LED source.
• Comparison of spectroscopic measurements with and without integrated cavity mirrors.

Main Results:

• The integrated cavity mirrors enhanced the absorption path length by a maximum factor of 28 at 544 nm.
• Spectroscopic sensitivity was improved approximately 5-fold compared to measurements without cavity mirrors.
• Micromolar detection limits were achieved within a short optical path length of 50 micrometers.

Conclusions:

• The developed microfluidic chip with integrated cavity mirrors is an effective platform for highly sensitive absorption spectroscopy.
• This approach enables miniaturized and cost-effective analytical systems for various applications.
• The integration of optical cavities into microfluidics represents a significant advancement in portable spectroscopic analysis.