A Nonswelling Hydrogel with Regenerable High Wet Tissue Adhesion for Bioelectronics

Abstract

Reducing the swelling of tissue‐adhesive hydrogels is crucial for maintaining stable tissue adhesion and inhibiting tissue inflammation. However, reported strategies for reducing swelling always result in a simultaneous decrease in the tissue adhesive strength of the hydrogel. Furthermore, once the covalent bonds break in the currently reported hydrogels, they cannot be rebuilt, and the hydrogel loses its tissue adhesive ability. In this work, a nonswelling hydrogel (named as “PAACP”) possessing regenerable high tissue adhesion is synthesized by copolymerizing and crosslinking poly(vinyl butyral) with acrylic acid, gelatin, and chitosan‐grafted N‐acetyl‐l‐cysteine. The tissue adhesive strength of the obtained PAACP reaches 211.4 kPa, which is approximately ten times higher than that of the reported nonswelling hydrogels, and the hydrogel can be reused for multiple cycles. The as‐prepared hydrogel shows great potential in soft bioelectronics, as muscle fatigue is successfully monitored via the electrode array and strain sensor integrated on PAACP substrates. The success of these bioelectronics offers potential applicability in the long‐term diagnosis of muscle‐related health conditions and prosthetic manipulations.

Highly Sensitive and Omnidirectionally Stretchable Bioelectrode Arrays for In Vivo Neural Interfacing

“…We used a 2 × 2 electrode array (four channels) to collect electrophysiological signal ( Figure a). Because of the weak adhesion between the PDMS substrate and tissue, a highly adhesive and nonswelling hydrogel [ 46 ] was used to adhere PEA to the tissue. The PEA can achieve conformal contact with soft biological tissues (Figure S23, Supporting Information, shows images of conformal contact between PEA and biological tissues, and Figure S24, Supporting Information, shows schematic of electrode adhesion to tissue using hydrogel as glue).…”

Functionalization of Natural-Derived Biogels for Soft Bioelectronics

“…Designing multiple noncovalent cross-linking interactions between biopolymer chains, such as electrostatic interaction, hydrogen bonds, hydrophobic interaction, metal coordination, and microcrystalline domains, to improve the cross-linking density of biogels is an effective strategy to improve their swelling resistance. , Designing the antiswelling property of biogels by multiple interaction strategies generally results in simultaneous change of their mechanical strength due to the formation of a high cross-linking density in the biogel matrix. Additionally, introducing hydrophobic groups to biopolymer chains or constructing other hydrophobic polymer networks into the biogel matrix is conducive to weakening the hydrophilicity of biogels, restricting their swelling, and then improving their structural and functional stability …”

Wide Range Strain Distributions on the Electrode for Highly Sensitive Flexible Tactile Sensor with Low Hysteresis

“…At present, most strategies for overcoming the sensitivity limit of soft tactile sensors are focused on building microstructures on an elastomer substrate (e.g., polydimethylsiloxane (PDMS), Ecoflex, polyurethane, etc. ). , For piezoresistive pressure sensors, elastomer microstructures must be conductive. Normally, carbon-based materials (reduced graphite oxide and carbon nanotubes − ), conductive polymers (poly­(3,4-ethylenedioxythiophene) and polypyrrole), or metal materials (silver nanoparticles and gold (Au)) are added to the surface or inside the elastomer microstructures to provide conductivity.…”