Spontaneous surface reserve formation in wicked membranes bestow extreme stretchability

Abstract: Soft stretchable materials are key for arising technologies such as stretchable electronics or batteries, smart textiles, biomedical devices, tissue engineering and soft robotics. Recent attempts to design such materials, via e.g. micro-patterning of wavy fibres on soft substrates, polymer engineering at the molecular level or even kirigami techniques, provide appealing prospects but suffer drawbacks impacting the material viability: complexity of manufacturing, fatigue or failure upon cycling, restricted range of materials or biological incompatibility. Here, we report a universal strategy to design highly stretchable, self-assembling and fatigue-resistant synthetic fabrics. Our approach finds its inspiration in the mechanics of living animal cells that routinely encounter and cope with extreme deformations, e.g. with the engulfment of large intruders by macrophages, squeezing and stretching of immune cells in tiny capillaries or shrinking/swelling of neurons upon osmotic stimuli. All these large instant deformations are actually mediated and buffered by membrane reserves available in the form of microvilli, membrane folds or endomembrane that can be recruited on demand. We synthetically mimicked this behavior by creating nanofibrous liquid-infused tissues spontaneously forming surface reserves whose unfolding fuels any imposed shape change. Our process, relying only on geometry, elasticity and capillarity, allows to endow virtually any material with high stretchability and reversibility, making it straightforward to implement additional mechanical, electrical or chemical functions. We illustrate this with proof-of-concept activable capillary muscles, adaptable slippery liquid infused porous surfaces and stretchable basic printed electronic circuits.