This review critically analyzes degradable biomedical elastomers, focusing on their degradation, synthesis, microstructure, and role in tissue repair. It guides experts in balancing degradation with tissue repair for improved applications.

Membrane-type acoustic metamaterial (MAM) has exhibited superior sound isolation properties, as well as thin and light characteristics. However, the anti-resonance modes of traditional MAMs are generated intermittently in a wide frequency range causing discontinuities in the anti-resonance modes. Achieving broadband low-frequency sound attenuation with lightweight MAM design is still a pivotal research aspect. Here, we present a strategy to realize wide sound-attenuation bands in low frequency range by introducing the design concept of bionic configuration philosophy into the MAM structures. Built by a polymeric membrane and a set of resonators, two kinds of MAM models are proposed based on the insight of a spider web topology. The sound attenuation performance and physical mechanisms are numerically and experimentally investigated. Multi-state anti-resonance modes, induced by the coupling of the bio-inspired arrangement and the host polymer film, are systematically explored. Significant sound attenuation is numerically and experimentally observed in both the lightweight bio-inspired designs. Remarkably, compared with a traditional MAM configuration, a prominent enhancement in both attenuation bandwidth and weight-reduction performance is verified. In particular, the bio-inspired MAM Model I exhibits a similar isolation performance as the reference model, but the weight is reduced by nearly half. The bio-inspired Model II broadens the sound attenuation bandwidth greatly; meanwhile, it retains a lighter weight design. The proposed bio-inspired strategies provide potential ways for designing sound isolation devices with both high functional and lightweight performance.

Efficiently and precisely designed isotropic auxetic metamaterials present significant challenges due to the inherent uncertainties in their geometric configurations. This study introduces an innovative data-driven structural design strategy that enables accurate prediction of the mechanical properties and inverse design for isotropic auxetic metamaterials. Notably, Kolmogorov–Arnold networks (KANs) are utilized, replacing fixed activation functions with learnable functions, to successfully establish a precise mapping between design parameters and mechanical responses for classical missing rib auxetic metamaterials. The predicted mean square error (MSE) for the stress dataset is as low as 0.81%, only one-fourth of that achieved by multilayer perceptron (MLP) models of equivalent width, while computational efficiency surpasses finite element methods by more than 10³ times. Building on this mapping, Model III, optimized using a genetic algorithm, achieves an average MSE of just 0.05%, significantly outperforming the original structure (Model I) and a randomly perturbed structure (Model II) with an average MSE of 2.28% and 1.79%, respectively. Experimental validation and finite element analysis further confirm the accuracy of these results, demonstrating the successful realization of isotropic mechanical response designs. This study presented a data-driven inverse design method as a powerful and efficient tool for the precise design of auxetic metamaterials with isotropic mechanical responses. It holds particular promise for applications in flexible wearable devices and tissue engineering, providing a robust foundation for future innovations in these fields.

Developing patches that effectively merge intrinsic deformation characteristics of cardiac with superior tunable mechanical properties remains a crucial biomedical pursuit. Currently used traditional block-shaped or mesh patches, typically incorporating a positive Poisson's ratio, often fall short of matching the deformation characteristics of cardiac tissue satisfactorily, thus often diminishing their repairing capability. By introducing auxeticity into the cardiac patches, this study is trying to present a beneficial approach to address these shortcomings of the traditional patches. The patches, featuring the auxetic effect, offer unparalleled conformity to the cardiac complex mechanical challenges. Initially, scaffolds demonstrating the auxetic effect were designed by merging chiral rotation and concave angle units, followed by integrating scaffolds with a composite hydrogel through thermally triggering, ensuring excellent biocompatibility closely mirroring heart tissue. Tensile tests revealed that auxetic patches possessed superior elasticity and strain capacity exceeding cardiac tissue's physiological activity. Notably, Model III showed an equivalent modulus ratio and Poisson's ratio closely toward cardiac tissue, underscoring its outstanding mechanical potential as cardiac patches. Cyclic tensile loading tests demonstrated that Model III withstood continuous heartbeats, showcasing outstanding cyclic loading and recovery capabilities. Numerical simulations further elucidated the deformation and failure mechanisms of these patches, leading to an exploration of influence on mechanical properties with alternative design parameters, which enabled the customization of mechanical strength and Poisson's ratio. Therefore, this research presents substantial potential for designing cardiac auxetic patches that can emulate the deformation properties of cardiac tissue and possess adjustable mechanical parameters.