Conductive hydrogels are widely used in various applications, such as artificial skin, flexible and implantable bioelectronics, and tissue engineering. However, it is still a challenge to formulate...

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Functional Conductive Hydrogels for Bioelectronics

Conductive self-healing hydrogels (CSHs) that match the mechanical properties of biological tissues are highly desired for emerging wearable electronics. However, it is still a fundamental challenge to balance the trade-offs among the mechanical, electronic, and self-healing properties in CSHs. In this study, we presented supramolecular double-network (DN) CSHs by pre-infiltrating conductive polyaniline (PANI) precursor into the self-healable hydrophobic association poly(acrylic acid) (HAPAA) hydrogel matrix. The dynamic interfacial interactions between the HAPAA and PANI networks efficiently enhanced the mechanical performances of the HAPAA/PANI (PAAN) hydrogel and could compensate for the negative effect of the enhanced mechanical strength on self-healing. In addition, the interconnected PANI network endowed the PAAN hydrogel with high conductivity and excellent sensory performances. As such, the mechanical and electronic properties of the PAAN hydrogel were simultaneously enhanced significantly without compromising the self-healing performance of the HAPAA matrix, achieving balanced mechanical, electronic, and self-healing properties in the PAAN hydrogel. Lastly, proof-of-concept applications like human physiological monitoring electronics, flexible touch screens, and artificial electronic skin are successfully demonstrated using the PAAN hydrogel with the capability of restoring their electronic performances after the healing process. It is anticipated that such hydrogel network design can be extended into next-generation hydrogel electronics for human–machine-interfaces and soft robotics.

Balancing the mechanical, electronic, and self-healing properties in conductive self-healing hydrogel for wearable sensor applications

Hydrogels that combine the integrated attributes of being adhesive, self-healable, deformable, and conductive show great promise for next-generation soft robotic/energy/electronic applications. Herein, we reported a dual-network polyacrylamide (PAAM)/poly(acrylic acid) (PAA)/graphene (GR)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) (MAGP) conductive hydrogel composed of dual-cross-linked PAAM and PAA as well as PEDOT:PSS and GR as a conducting component that combines these features. A wearable strain sensor is fabricated by sandwiching the MAGP hydrogels between two dielectric carbon nanotubes (CNTs)/poly(dimethylsiloxane) (PDMS) layers, which can be utilized to monitor delicate and vigorous human motion. In addition, the hydrogel-based sensor can act as a deformable triboelectric nanogenerator (D-TENG) for harvesting mechanical energy. The D-TENG demonstrates a peak output voltage and current of 141 V and 0.8 μA, respectively. The D-TENG could easily light 52 yellow-light-emitting diodes (LEDs) simultaneously and demonstrated the capability to power small electronics, such as a hygrometer thermometer. This work provides a potential approach for the development of deformable energy sources and self-powered strain sensors.

Stretchable, Adhesive, Self-Healable, and Conductive Hydrogel-Based Deformable Triboelectric Nanogenerator for Energy Harvesting and Human Motion Sensing.

Processing, mechanical properties and bio-applications of silk fibroin-based high-strength hydrogels

The ongoing surge in demand for high-performance wearable sensors for precisely monitoring vital signs of the human body or the surrounding environment has inspired the relentless pursuit of biocompatible and biodegradable advanced materials. Cellulose, as a class of well-known natural biopolymer on the Earth, presents distinctive integrated merits of good biocompatibility and biodegradability, easy processability into diverse material formats, and sustainable production on a large scale, as well as intrinsic shape anisotropy, surface charge/chemistry, and superior physical and mechanical properties. Such unique advantages have driven constant innovations in wearable and smart cellulose-containing sensors in the past few years. With the rapid development of fabrication techniques in material processing and progress in research, cellulose has been engineered into multidimensional architectures including 1D (nanofibers, fibers, and yarns), 2D (paper, films, and fabrics), and 3D (hydrogels, aerogels, foams, and sponges), which are further transformed into electrically conductive carbonaceous materials with tailorable structures and properties. Cellulose-derived materials have been developed as flexible biosupports or biosubstrates, sensing layers, electrodes and active components for wearable sensors by virtue of their favorable and unique material merits. In this review, the recent advances in the development of multidimensional and multifunctional cellulose-derived materials are discussed for wearable sensors toward healthcare and environment monitoring. First of all, the unique hierarchical and chemical structures and properties of cellulose are briefly introduced. Then, we summarize the fabrication strategies for processing cellulose into materials with multidimensional architectures. Additionally, the design and functionality of flexible wearable sensors developed with multidimensional cellulose-derived materials as biosubstrates, electrodes, active layers, and sensing components are presented in detail. In particular, cellulose-based advanced materials for self-powered sensors are also highlighted. Finally, some prospects on the future challenges in this emerging research field of designing cellulose-derived materials for wearable sensors are illustrated. This review may provide insightful inspiration for the design and utilization of cellulosic composites in flexible electronic devices with high-performance.

Emerging cellulose-derived materials: a promising platform for the design of flexible wearable sensors toward health and environment monitoring

It is a great challenge to fabricate self-healing hydrogels that simultaneously possess high mechanical strength and good elasticity, and are capable of rapidly and efficiently healing physical dam...

Dynamic Hydrophobic Domains Enable the Fabricationof Mechanically Robust and Highly Elastic Poly(vinyl alcohol)-BasedHydrogels with Excellent Self-Healing Ability

Xianghui Yu

Papers

Dynamic Hydrophobic Domains Enable the Fabricationof Mechanically Robust and Highly Elastic Poly(vinyl alcohol)-BasedHydrogels with Excellent Self-Healing Ability