A composite optical filter greenly fabricated for living algae detection

Area of Science:

• Materials Science
• Optical Engineering
• Biotechnology

Background:

• Microfluidic devices offer miniaturization advantages but often require bulky optical components.
• Integrating optical filtration directly into microfluidic chips can reduce device size and complexity.
• Chlorophyll fluorescence detection is crucial for environmental monitoring and biological studies.

Purpose of the Study:

• To develop a green fabrication method for a composite polydimethylsiloxane (PDMS) filter (C-filter) with integrated optical amplification.
• To reduce the size of microfluidic devices by incorporating optical filtration functionality.
• To enhance chlorophyll fluorescence detection for applications like living algae monitoring.

Main Methods:

• Fabricated a polydimethylsiloxane (PDMS) microfluidic chip as a sub-filter (S-filter) by soaking in Sudan II dye dissolved in ethanol.
• Created an optical amplification sub-filter (F-lens) using crystal violet dissolved in dimethyl-methylhydrogenosiloxane and dimethyl-methylvinylsiloxane.
• Utilized ethanol as a green solvent for dye dissolution, replacing traditional solvents like phenol and toluene.

Main Results:

• The S-filter effectively filters light in the 400-500 nm range.
• The F-lens filters light within the 500-650 nm range.
• The composite filter (C-filter) demonstrated high transmittance (99.33%) in the 650-710 nm range, outperforming commercial filters (96.72%).

Conclusions:

• Ethanol is a viable and eco-friendly solvent for dye dissolution in filter fabrication.
• The developed C-filter effectively integrates optical filtration and amplification, enabling efficient chlorophyll fluorescence detection.
• This approach significantly advances the miniaturization of optical microfluidic systems for biological and environmental sensing.