Tough Mechanically Interlocked Transparent Interface of Hydrogels and Elastomers for Biomedical Applications

Abstract

Hydrogel‐based soft, wet devices receive a great deal of attention in advanced medical engineering, which will require integration of hydrogels and elastomers through a transparent and tightly bound interface. Here, the strength of the mechanical interlock of the hydrogel–elastomer interface is studied using microstructured poly(dimethylsiloxane) (PDMS) sheets embedded in a polyvinyl alcohol (PVA) hydrogel. The PDMS sheet, which exhibits micro‐protrusions (cuboid and frustum‐shape), has a tensile strength of 10 kPa, which can be sufficient for gentle handling of the PVA/PDMS assembly. The PDMS protrusions (even the frustum‐shape) are found to drag out from the deformed PVA hydrogel without any destruction. The tensile strength of the embedded PDMS is further increased by attaching a thin roof film to bridge the protrusions. These microbridge structures are more than ten times stronger than those with only protrusions, and extraction of the PDMS microbridges caused the destruction of PVA hydrogel. It is also confirmed by a 90°‐peeling test that the microbridge structure is effective for tough lamination of the PVA on PDMS. The PVA/PDMS assembly with the microbridged interface exhibits transparency and deformability that will be sufficient for biomedical applications.