An Easy Method for the Fabrication of Solvent-Resistant Microfluidic Chips

Coating a PDMS device with a fluoropolymer opens up new ways for on-chip organic synthesis

Dr. Tianjin Yang and coworkers in the deMello group have developed a new route for the easy fabrication of solvent-resistant microfluidic reactors using a polymer coating. The robustness of the device is demonstrated by the successful performance of organic reactions in harsh conditions.

Recently, microfluidic-based reactors have attracted a lot of interest for chemical synthesis, owing to the unique properties offered by microscale environments. While PDMS-based microfluidic chips are well-suited for biological applications, most chemical synthesis reactions require conditions that are incompatible with the fragility of PDMS, such as aggressive organic solvents and strongly acidic or basic conditions. For this reason, microfluidic reactors used in small-molecule synthesis have been mostly fabricated from chemically inert materials using conventional lithographic techniques. In this context, a fabrication route based on the simpler and cheaper soft-lithography technique is desired.

In the present work, researchers from our group tackle this problem by leveraging the solvent-resistant properties of CYTOP, a commercially available fluoropolymer, and developing a procedure for the formation of a stable polymer layer on the surface of PDMS. After the activation of the PDMS surface with oxygen plasma, the method simply requires two consecutive surface modification steps: a first treatment to attach amino groups on the surface, followed by the spin coating of CYTOP that covalently binds to the amino groups by the formation of amide bonds. Two such modified PDMS layers are then thermally bonded to form the final device. The carrying-out of a photooxidation reaction as well as reactions under strongly acidic or basic conditions provides proof-of-concept for the robustness of the resulting CYTOP-coated microfluidic reactor. The straightforward procedure along with the commercial availability of the fluoropolymer is expected to allow researchers to readily adopt this method for a wide range of application in organic synthesis.

Written by Julie Probst.

Read the full paper here.

After completion of the solvent-resistant coating procedure, the channel walls show no distortion even after extended exposure to an organic solvent

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