Intrinsically Nonswellable Multifunctional Hydrogel with Dynamic Nanoconfinement Networks for Robust Tissue‐Adaptable Bioelectronics

Abstract

Developing bioelectronics that retains their long-term functionalities in the human body during daily activities is a current critical issue. To accomplish this, robust tissue adaptability and biointerfacing of bioelectronics should be achieved. Hydrogels have emerged as promising materials for bioelectronics that can softly adapt to and interface with tissues. However, hydrogels lack toughness, requisite electrical properties, and fabrication methodologies. Additionally, the water-swellable property of hydrogels weakens their mechanical properties. In this work, an intrinsically nonswellable multifunctional hydrogel exhibiting tissue-like moduli ranging from 10 to 100 kPa, toughness (400-873 J m −3 ), stretchability (≈1000% strain), and rapid self-healing ability (within 5 min), is developed. The incorporation of carboxyland hydroxyl-functionalized carbon nanotubes (fCNTs) ensures high conductivity of the hydrogel (≈40 S m −1 ), which can be maintained and recovered even after stretching or rupture. After a simple chemical modification, the hydrogel shows tissue-adhesive properties (≈50 kPa) against the target tissues. Moreover, the hydrogel can be 3D printed with a high resolution (≈100 μm) through heat treatment owing to its shear-thinning capacity, endowing it with fabrication versatility. The hydrogel is successfully applied to underwater electromyography (EMG) detection and ex vivo bladder expansion monitoring, demonstrating its potential for practical bioelectronics.

Universal Hydrogel Adhesives with Robust Chain Entanglement for Bridging Soft Electronic Materials

“…The foundational design comprises a stretchable Eco-ex substrate fashioned into a circular con guration. On this substrate, a carbon nanotube (CNT) hydrogel 43 responsible for sensing, and a conductive thread for transmitting data were a xed by utilizing d-HAPT. The fabricated strain sensors exhibited excellent softness due to the intrinsic stretchability of conductive hydrogel and Eco-ex.…”

3D Printing of Self‐Healing Materials

“…Interestingly, often functional properties are recovered faster than mechanical ones, making those materials even more appealing. [301] In this frame, SH 3D printed constructs were exploited to fabricate reusable [226,227,251,[255][256][257]278,280,287] and wearable [233,245,249] sensors, as well as other devices such as supercapacitors [241] or other energy storage systems [258] , electronic skins [248] or, in general, devices able to transport electrical charges. [260,265]…”

“…Similarly, a mixture of PVA, Poly(Acrylic Acid) (PAA), and tannic acid was studied to develop flexible bioelectronics. [249] In this case, SH was guaranteed by distributed H-bonding, while electrical conductivity was given by adding functionalized CNT.…”

Electrochemical and Electrical Biosensors for Wearable and Implantable Electronics Based on Conducting Polymers and Carbon-Based Materials

“…An intimate and stable contact between the electrodes and the tissues is one of the key requirements for wearable and implantable biosensors. − Several strategies have been developed to improve the adhesiveness between the tissues and electrodes, including: 1) applying an adhesive layer to the electrodes, , 2) mixing adhesive components into the conductive material, and 3) functionalization of the organic conducting materials through chemical modification …”