Low Cost, Ease-of-Access Fabrication of Microfluidic Devices Using Wet Paper Molds

Area of Science:

• Materials Science
• Engineering
• Biotechnology

Background:

• Microfluidic technologies are increasingly adopted, but their widespread use is limited by complex and expensive fabrication methods.
• Rapid prototyping offers a solution by enabling accessible device creation for non-engineers.
• Existing methods like photolithography and 3D printing have limitations in cost and simplicity.

Purpose of the Study:

• To develop a simple, inexpensive, and rapid method for fabricating polydimethylsiloxane (PDMS) microfluidic devices.
• To demonstrate the feasibility of using wet paper molds for replica molding of microfluidic devices.
• To explore the advantages of this novel technique over conventional fabrication methods.

Main Methods:

• A liquid molding technique using replica molding with wet paper molds was developed.
• Paper molds were fabricated using adhesive-backed paper, an acetate backing sheet, and a digital cutter.
• Water was used to create the liquid mold pattern due to the immiscibility with PDMS.

Main Results:

• Successful fabrication of PDMS microfluidic devices using wet paper molds was demonstrated.
• Channel cross-sectional shape could be tuned from rectangular to semicircular by adjusting wetting parameters.
• Electrical impedance was validated as a non-invasive method for mold quality inspection and defect detection.
• A proof-of-concept microfluidic T-junction droplet generator was created, producing droplets from 1.2 µL to 75 µL.

Conclusions:

• The developed wet paper mold technique is a viable and advantageous addition to the microfluidic rapid prototyping toolbox.
• This method offers benefits such as adjustable channel geometry and non-invasive quality control.
• The technique has potential applications in biological research and democratizes microfluidic device fabrication.