Figure 6. Patches displaying both anisotropic and auxetic properties.

Patches featuring a combination of anisotropy and auxetic architectures developed by Kapnisi and colleagues [38] (Panel A) and Boley and colleagues [77] (Panel B). A. (i) Scheme of administration of the auxetic cardiac patches (AuxCP) on the heart and the deformation characteristics of re-entrant architectures. The stiffer orientation of the re-entrant architecture is aligned with the stiffer transverse direction. (ii) Example of the optimization of design feature – dimension “A” relating to the height of the re-entrant architecture – to achieve cardiac-mimicking longitudinal and transverse stiffness. (iii) AuxCP attached via laser photoadhesion to the left ventricle of a MI-induced rat (scale bar: 4 mm). Hematoxylin and eosin (H&E) stain demonstrating sustained patch adherence (scale bar: 2 mm). B. (i) Schematic of a multi-material printed structure containing PDMS with short glass fibers aligned along the print direction due to shear forces, and schematic of a 2D heterogeneous lattice capable of morphing into a spherical cap when cooled. (ii) Artificial intelligence-based spatial programming of the printing ink constitution, which allows the creation of a 3D face as the resting shape of the flat printed architecture. Image reproduced with permission from [38] and [77].