In situ roughening of polymeric microstructures

Area of Science:

• Materials Science
• Surface Engineering
• Biomaterials

Background:

• Microstructures often exhibit weak adhesion to substrates, limiting their applications.
• Improving surface properties is crucial for enhanced biomolecule and cell interactions.
• Current methods for surface modification can be complex or damaging.

Purpose of the Study:

• To develop and evaluate a method for in situ roughening of microstructures.
• To assess the impact of roughening on surface properties and microstructure integrity.
• To investigate the effect of roughening on biomolecule and cell adhesion, and microcontact printing.

Main Methods:

• Arrays of SU8, 1002F, and polydimethylsiloxane (PDMS) microstructures were roughened using a particle slurry.
• Surface roughness was measured using RMS roughness after varying polishing times.
• Microstructure integrity was assessed by quantifying dislodged or damaged structures.
• Fibronectin adhesion and cell attachment/growth were evaluated on native and roughened surfaces.
• Microcontact printing efficiency was measured using BSA-Alexa Fluor 647 transfer.

Main Results:

• Particle slurry polishing achieved maximal RMS roughness of 7-18 nm within 15-30 s, a 4-9 fold increase.
• Less than 0.8% of microstructures were damaged after 5 minutes of polishing.
• Fibronectin adhesion increased two-fold, and cell adhesion was enhanced on roughened surfaces.
• Microcontact printing showed up to a 20-fold improvement in molecule transfer when roughening PDMS stamps and substrates.

Conclusions:

• In situ surface roughening with a particle slurry effectively increases surface roughness of microstructures.
• The method enhances biomolecule and cell adhesion to microstructures with minimal damage to the array.
• This technique offers a simple and efficient way to improve surface functionality for microdevices and printing applications.