Hydrogel bioelectronics that can interface biological tissues and flexible electronics is at the core of the growing field of healthcare monitoring, smart drug systems, and wearable and implantable devices. Here, a simple strategy is demonstrated to prototype all‐hydrogel bioelectronics with embedded arbitrary conductive networks using tough hydrogels and liquid metal. Due to their excellent stretchability, the resultant all‐hydrogel bioelectronics exhibits stable electrochemical properties at large tensile stretch and various modes of deformation. The potential of fabricated all‐hydrogel bioelectronics is demonstrated as wearable strain sensors, cardiac patches, and near‐field communication (NFC) devices for monitoring various physiological conditions wirelessly. The presented simple platform paves the way of implantable hydrogel electronics for Internet‐of‐Things and tissue–machine interfacing applications.

Creating complex three-dimensional structures from soft yet durable materials enables advances in fields such as flexible electronics, regenerating tissue engineering, and soft robotics. Tough hydrogels that mimic the human skin can bear enormous mechanical loads. By employing a spider-inspired biomimetic microfluidic nozzle, we successfully achieve continuous printing of tough hydrogels into fibers, two-dimensional networks, and even three-dimensional structures without compromising their extreme mechanical properties. The resultant thin fibers demonstrate a stretch up to 21 times of their original length at a water content of 52%, and are intrinsically transparent, biocompatible, and conductive at high stretches. Moreover, the printed robust tough-hydrogel networks can sense strain that are orders of magnitude lower than stretchable conductors by percolations of conductive particles. To demonstrate their potential application, we use printed tough-hydrogel fiber networks as wearable sensors for detecting human motions. The capability to shape tough hydrogels into complex structures by scalable continuous printing opens opportunities for new areas of applications such as tissue scaffolds, large-area soft electronics, and smart textiles.

Sponges, Neofibularia nolitangere, can regenerate spontaneously after being broken down into small pieces, and the regenerated structure maintains the original appearance and function. Synthetic materials with such capabilities are highly desired but hardly achieved. Presented here is a sponge‐inspired self‐regenerative powder from a double‐network (DN) tough hydrogel. Hydrogels are regenerated from their powder form, by addition of water, with preservation of the original appearance and mechanical properties. The powder‐hydrogel‐powder cycle can be repeated multiple times with little loss in mechanical properties, analogous to the regeneration of sponges. These DN hydrogels can be conveniently stored and easily shaped upon regeneration. This work may have implications in the development of regenerative materials for coatings and adhesives.

Sponges, Neofibularia nolitangere, can regenerate spontaneously after being broken down into small pieces, and the regenerated structure maintains the original appearance and function. Synthetic materials with such capabilities are highly desired but hardly achieved. Presented here is a spongeinspired self-regenerative powder from a double-network (DN) tough hydrogel. Hydrogels are regenerated from their powder form, by addition of water, with preservation of the original appearance and mechanical properties. The powderhydrogel-powder cycle can be repeated multiple times with little loss in mechanical properties, analogous to the regeneration of sponges. These DN hydrogels can be conveniently stored and easily shaped upon regeneration. This work may have implications in the development of regenerative materials for coatings and adhesives.In nature many animals can heal and regenerate after severe injury or even loss of significant bodily portions. [1][2][3] Sponges, Neofibularia nolitangere, the simplest form of multicellular organisms, has a fascinating regenerative capacity. [1,2] In sea water, small fragments of cell aggregates that are dissociated from Neofibularia nolitangere can fuse into functional mass and reassemble into its original form after being prompted. The regeneration of Neofibularia nolitangere is a consequence of a complex collaboration of multiple cell types through metabolism. [1,2] The capacity for reconstruction after injury is rare, but highly desired in synthetic materials, which typically deteriorate and even fail after repetitive exposure to mechanical strain.There are some reports addressing self-healing materials that can partially, or even completely restore their mechanical properties. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Existing self-healing strategies based on either dynamic covalent or physical bonds have certain limitations. [5, 10-12, 15, 22-26] For instance, self-healing strategies based on supramolecular interactions are inefficient for healing a large area with severe damage, [12,15,16,21,27,28] for self-healing of physical bonds when the damage is no longer fresh because the effect of healing becomes weak and even disappears, [25,26,[29][30][31] and for repair of dynamic covalent bonds because external conditions need be applied. [22,32,33] Moreover, most healing strategies cannot be applied in both wet and dry conditions. [20,34,35] Although the development progress of self-healing materials has been impressive, those capable of regaining their properties rapidly from aged and severe damage are scarce. [36] Healing to restore the original form and full function, like Neofibularia nolitangere, even when reduced into countless pieces, is still desired for most synthetic materials.Herein we report a sponge-inspired strategy to develop self-regenerative materials. Based on double-network (DN) tough hydrogels, we fabricate hydrogel powders that can regenerate to restore the original form and appearance of the hydrogel, and almost restore...

In this work, we investigate the pulsation of an electrically charged jet surrounded by an immiscible dielectric liquid in flow-focusing capillary microfluidics. We have characterized a low-frequency large-amplitude pulsation and a high-frequency small-amplitude pulsation, respectively. The former, due to the unbalanced charge and fluid transportation is responsible for generating droplets with a broad size distribution. The latter is intrinsic and produces droplets with a relatively narrow size distribution. Moreover, the average size of the final droplets can be tuned via the intrinsic pulsating frequency through changing the diameter of the emitted liquid jet. Our results provide degree of control over the emulsion droplets with submicron sizes generated in microfluidic-electrospray platform.