Fabrication of Paper-based Microfluidic Devices Using a Laser Beam Scanning Technique

Area of Science:

• Materials Science
• Analytical Chemistry
• Microfluidics

Background:

• Paper-based microfluidic devices offer a low-cost platform for diagnostics.
• Fabrication of precise hydrophilic/hydrophobic patterns is crucial for device functionality.
• Existing methods for patterning paper can be complex or lack resolution.

Purpose of the Study:

• To develop a novel, high-resolution method for fabricating paper-based microfluidic devices.
• To demonstrate the creation of arbitrary hydrophilic patterns on hydrophobic paper using laser-induced chemistry.
• To validate the performance of the fabricated device for chemical quantification.

Main Methods:

• Cellulose chromatography paper was rendered hydrophobic using octadecyltrichlorosilane (OTS).
• A photoacid generator (CPI-410S) was incorporated into the paper.
• Laser beam scanning (405-nm) induced localized hydrolysis of silyl ether bonds, creating hydrophilic regions.
• A Galvo mirror system controlled laser scanning for arbitrary pattern generation with 50 μm resolution.

Main Results:

• Arbitrary hydrophilic patterns were successfully fabricated on OTS-treated paper with high resolution.
• The method demonstrated the first use of photo-induced acid generation coupled with laser scanning for this purpose.
• The fabricated paper microfluidic device was successfully used for the quantification of nitrite.

Conclusions:

• A novel and efficient laser-based technique for fabricating paper microfluidic devices has been established.
• This method allows for precise control over channel geometry and hydrophilicity on paper substrates.
• The developed device shows promise for sensitive and low-cost chemical analysis applications.