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Mechanically flexible and conformable materials and integrated devices have found diverse applications in personalized healthcare as diagnostics and therapeutics, tissue engineering and regenerative medicine constructs, surgical tools, secure systems, and assistive technologies. In order to impart optimal mechanical properties to the (bio)materials used in these applications, various strategies have been explored—from composites to structural engineering. In recent years, geometric cuts inspired by the art of paper‐cutting, referred to as kirigami, have provided innovative opportunities for conferring precise mechanical properties via material removal. Kirigami‐based approaches have been used for device design in areas ranging from soft bioelectronics to energy storage. In this review, the principles of kirigami‐inspired engineering specifically for biomedical applications are discussed. Factors pertinent to their design, including cut geometry, materials, and fabrication, and the effect these parameters have on their properties and configurations are covered. Examples of kirigami designs in healthcare are presented, such as, various form factors of sensors (on skin, wearable), implantable devices, therapeutics, surgical procedures, and cellular scaffolds for regenerative medicine. Finally, the challenges and future scope for the successful translation of these biodesign concepts to broader deployment are discussed.

Substrates that are simultaneously thin, strong, optically transparent, and biocompatible have diverse applications in a range of fundamental and applied fields. While nature-derived materials offer advantages of sustainability and inherent biocompatibility compared to synthetic polymers, their brittleness and swelling, as well as surface charge and chemical functionalization non-conducive to cell growth, can hinder widespread application. In this work, we discuss the fabrication and systematic characterization of polydopamine-coated chitosan thin films. Chitosan is a widely used, partially deacetylated form of chitin, derived from crustaceans and arthropods. Polydopamine (PDA) is derived from chemistries mimicking mussel foot adhesive proteins. A facile dip-coating process of thin and flexible, uncrosslinked chitosan films in aqueous dopamine solutions leads to dramatic changes in physical and chemical properties. We show how the PDA forms time-dependent assemblies on the film surfaces, affecting surface roughness, hydrophilicity, and mechanical strength. Coating the surface for even a few seconds provides functional changes to the films. Our results shows that the optimal coating time is on the order of few hours, whereby the films are optically transparent with excellent extensibility and Young’s modulus, while further coating reduces the benefits of this surface coating. These materials are biocompatible, serving as substrates for cell adhesion and growth while maintaining good viability. Overall, these findings give insight to the effects of PDA assembly on surfaces, and illustrate how a simple, quick, and robust bioinspired coating process can prime substrates for biomedical applications such as tissue engineering, biosensing, and wound healing.

Biomimetic substrates that incorporate functionality such as electroactivity and mechanical flexibility, find utility in a variety of biomedical applications. Toward these uses, naturederived materials such as gelatin offer inherent biocompatibility and sustainable sourcing. However, issues such as high swelling, poor mechanical properties, and lack of stability at biological temperatures limit their use. The enzymatic crosslinking of gelatin via microbial transglutaminase (mTG) yields flexible and robust large area substrates that are stable under physiological conditions. Here, we demonstrate the fabrication and characterization of strong, stretchable, conductive mTG crosslinked gelatin thin films. Incorporation of the conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate in the gel matrix with a bioinspired polydopamine surface coating is used to enable conductivity with enhanced mechanical properties such as extensibility and flexibility, in comparison to plain gelatin or crosslinked gelatin films. The electroconductive substrates are conducive to cell growth, supporting myoblast cell adhesion, viability, and proliferation and could find use in creating active cell culture systems incorporating electrical stimulation. The substrates are responsive to motion such as stretching and bending while being extremely handleable and elastic, making them useful for applications such as electronic skin and flexible bioelectronics. Overall, this work presents facile, yet effective development of bioinspired conductive composites as substrates for bio-integrated devices and functional tissue engineering.

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