Bioinspired polydimethylsiloxane-based composites with high shear resistance against wet tissue

Patterned microstructures represent a potential approach for improving current wound closure strategies. Microstructures can be fabricated by multiple techniques including replica molding of soft polymer-based materials. However, polymeric microstructures often lack the required shear resistance with tissue needed for wound closure. In this work, scalable microstructures made from composites based on polydimethylsiloxane (PDMS) were explored to enhance the shear resistance with wet tissue. To achieve suitable mechanical properties, PDMS was reinforced by incorporation of polyethylene (PE) particles into the pre-polymer and by coating PE particle reinforced substrates with parylene. The reinforced microstructures showed a 6-fold enhancement, the coated structures even a 13-fold enhancement in Young's modulus over pure PDMS. Shear tests of mushroom-shaped microstructures (diameter 450 μm, length 1 mm) against chicken muscle tissue demonstrate first correlations that will be useful for future design of wound closure or stabilization implants.