Inkjet patterned superhydrophobic paper for open-air surface microfluidic devices

Area of Science:

• Materials Science
• Biomedical Engineering
• Microfluidics

Background:

• Superhydrophobic surfaces offer unique liquid manipulation properties.
• Paper-based microfluidic devices are cost-effective for diagnostics.
• Precise control over surface wettability is crucial for microfluidic applications.

Purpose of the Study:

• To develop a facile and low-cost method for fabricating surface microfluidic devices on superhydrophobic paper.
• To demonstrate tunable droplet sliding and adhesion properties.
• To enable applications in point-of-care diagnostics.

Main Methods:

• Drop-casting a fluoroacrylic copolymer onto microtextured paper to create superhydrophobic surfaces.
• Utilizing a common household printer for wettability patterning by controlling ink deposition intensity and width.
• Formulating a predictive model for droplet sliding onset on printed lines.

Main Results:

• Demonstrated tunable sliding angles for 10 μL water droplets (13°–40°) by varying printed line width and ink intensity.
• Achieved pumpless transport, mixing, and rapid droplet sampling (~0.6 μL at 50 Hz) in open-air surface microfluidic devices.
• Showcased utility in point-of-care diagnostics through post-treatment with pH indicator solutions.

Conclusions:

• This approach provides a cost-effective and accessible platform for advanced microfluidic applications.
• The developed method facilitates the creation of functional diagnostic tools for resource-limited settings.
• The tunable wettability offers versatile control over liquid behavior on paper-based devices.