Application of Micro/Nanoporous Fluoropolymers with Reduced Bioadhesion in Digital Microfluidics

Abstract

Digital microfluidics (DMF) is a versatile platform for conducting a variety of biological and chemical assays. The most commonly used set-up for the actuation of microliter droplets is electrowetting on dielectric (EWOD), where the liquid is moved by an electrostatic force on a dielectric layer. Superhydrophobic materials are promising materials for dielectric layers, especially since the minimum contact between droplet and surface is key for low adhesion of biomolecules, as it causes droplet pinning and cross contamination. However, superhydrophobic surfaces show limitations, such as full wetting transition between Cassie and Wenzel under applied voltage, expensive and complex fabrication and difficult integration into already existing devices. Here we present Fluoropor, a superhydrophobic fluorinated polymer foam with pores on the micro/nanoscale as a dielectric layer in DMF. Fluoropor shows stable wetting properties with no significant changes in the wetting behavior, or full wetting transition, until potentials of 400 V. Furthermore, Fluoropor shows low attachment of biomolecules to the surface upon droplet movement. Due to its simple fabrication process, its resistance to adhesion of biomolecules and the fact it is capable of being integrated and exchanged as thin films into commercial DMF devices, Fluoropor is a promising material for wide application in DMF.

Superrepellent Porous Polymer Surfaces by Replication from Wrinkled Polydimethylsiloxane/Parylene F

“…The preparation of repellent surfaces was achieved based on a modified preparation of previously reported Fluoropor foams [18][19][20][21][22]. Fluoropor is based on fluorinated methacrylates mixed with porogens.…”

“…When the micro-/nanostructure is introduced throughout the bulk, the superhydrophobicity is preserved after abrasion, as the material removal exposes a similar surface structure [16,17]. Fluoropor, which was pioneered by our group, is a micro-/nanoporous fluoropolymer with a bulk porosity that makes it insensitive to abrasion [18][19][20][21][22]. The bulk porosity is achieved by using a porogen mixture that contains an emulsifier and a nonsolvent.…”