Abstract
Replica molding is a widely used technique for the fabrication of polymer microstructures. As structural dimensions decrease, anti-stick surface treatment of the mold becomes increasingly critical to ensure clean demolding and preserve structural integrity. We fabricated arrays of micropillars with 20 µm diameter and 60 µm height using medical-grade polydimethylsiloxane (PDMS), MDX4-4210, and observed a high fraction of collapsed pillars for the first molding after fluorosilanization of the mold to reduce sticking. To address this issue, we systematically investigated the surface treatment protocol for the molds, made from the PDMS Sylgard 184. We provide results from complementary measurement methods, to show that an additional vacuum step partially removes unbound fluorosilane, but does not improve pillar stability. In contrast, a method based on multiple replications, where the first replication effectively removes residual fluorosilane from the mold, significantly enhances structural stability. Mechanical testing further revealed that the presence of fluorosilane lowers the Young's modulus of both PDMS materials, MDX4-4210 and Sylgard 184, suggesting interference with the curing process. Confocal Brillouin microscopy indicated an elongation of replicated pillars and revealed a softening close to the surfaces, as well as mechanical inhomogeneities in collapsed pillars. We discuss modifications to the molding protocol to improve the reproducibility and mechanical stability of the replicated microstructures, offering insights towards more reliable routes for the fabrication of residue-free, high-aspect ratio features with controlled surface chemistry.
Recommended Citation
G. Moreira Lana et al., "Fluorosilane-induced Softening And Collapse Of Micropillar Arrays," Journal of Micromechanics and Microengineering, vol. 35, no. 11, article no. 115009, IOP Publishing Ltd., Nov 2025.
The definitive version is available at https://doi.org/10.1088/1361-6439/ae1e87
Department(s)
Chemical and Biochemical Engineering
Publication Status
Open Access
Keywords and Phrases
anti-stick coating; fluorosilane; microstructure; PDMS; replica molding; surface treatment
International Standard Serial Number (ISSN)
1361-6439; 0960-1317
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2026 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
28 Nov 2025
Comments
European Research Council, Grant 842 613