A Versatile Microporous Design toward Toughened yet Softened Self-Healing Materials.

Realizing the full potential of self-healing materials in stretchable electronics necessitates not only low modulus to enable high adaptivity, but also high toughness to resist crack propagation. However, existing toughening strategies for soft self-healing materials have only modestly improves mechanical dissipation near the crack tip (ГD), and invariably compromise the material's inherent softness and autonomous healing capabilities. Here, a synthetic microporous architecture is demonstrated that unprecedently toughens and softens self-healing materials without impacting their intrinsic self-healing kinetics. This microporous structure spreads energy dissipation across the entire material through a bran-new dissipative mode of adaptable crack movement (ГA), which substantially increases the fracture toughness by 31.6 times, from 3.19 to 100.86 kJ m-2, and the fractocohesive length by 20.7 times, from 0.59 mm to 12.24 mm. This combination of unprecedented fracture toughness (100.86 kJ m-2) and centimeter-scale fractocohesive length (1.23 cm) surpasses all previous records for synthetic soft self-healing materials and even exceeds those of light alloys. Coupled with significantly enhanced softness (0.43 MPa) and nearly perfect autonomous self-healing efficiency (≈100%), this robust material is ideal for constructing durable kirigami electronics for wearable devices.

Robust and Multifunctional Kirigami Electronics with a Tough and Permeable Aramid Nanofiber Framework.

Kirigami designs are advantageous for the construction of wearable electronics due to their high stretchability and conformability on the 3D dynamic surfaces of the skin. However, suitable materials technologies that enable robust kirigami devices with desired functionality for skin-interfaces remain limited. Here, a versatile materials platform based on a composite nanofiber framework (CNFF) is exploited for the engineering of wearable kirigami electronics. The self-assembled fibrillar network involving aramid nanofibers and poly(vinyl alcohol) combines high toughness, permeability, and manufacturability, which are desirable for the fabrication of hybrid devices. Multiscale simulations are conducted to explain the high fracture resistance of the CNFF-based kirigami structures and provide essential guidance for the design, which can be further generalized to other kirigami devices. Various microelectronic sensors and electroactive polymers are integrated onto a CNFF-based materials platform to achieve electrocardiogram (ECG), electromyogram (EMG), skin-temperature measurements, and measurement of other physiological parameters. These mechanically robust, multifunctional, lightweight, and biocompatible kirigami devices can shed new insights for the development of advanced wearable systems and human-machine interfaces.