Materials of Controlled Shape and Stiffness with Photocurable Microfluidic Endoskeleton

Suk Tai Chang1, Ahmet Burak Ucar1, Robert O. Bradley1, Garrett Swindlehurst2, and Orlin D. Velev3. (1) Department of Chemical and Biomolecular Engineering, North Carolina State University, 911 Partners Way, Centennial Campus, NCSU, Raleigh, NC 27511, (2) Chemical Engineering, North Carolina State University, 911 Partners Way, Box 7905, Raleigh, NC 27695, (3) Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, NC 27695-7905

Microfluidic systems have been widely investigated for bioanalysis, organic and nanoparticle synthesis. The potential of microfluidics in other areas of technology, such as microfluidic adhesion, microsolidics and self-healing materials has only begun to be realized and investigated very recently. Here, we report a new class of microfluidic materials in the form of flexible sheets that can be solidified on demand to yield specific shapes. The novelty feature of these materials is that microfluidic channel networks are used for improving the mechanical properties of the large area polymer materials.

The microchannel networks in polydimethylsiloxane (PDMS) are filled with photo-curable polymers. When the microchannel networks are shaped and exposed by UV light, the photoresist inside the channels is solidified and acts as endoskeleton within the PDMS layer, acquiring the pre-arranged shape. Bending and stretching moduli of the materials with solidified endoskeleton increases drastically and once the external stress is removed, the memorized shapes are recovered. The materials and the process of preparation of these microfluidic materials are simple, inexpensive and scalable. The permanent preservation of the shape of solidified microfluidic sheets could be used in making instant packages and supports on demand for protecting delicate contents and multiple other applications.