Polyelectrolyte-based conductive hydrogels: from theory to applications

Abstract

With the continuous development of soft conductive materials, polyelectrolyte-based conductive hydrogels have gradually become a major research hotspot because of their strong application potential. This review first considers the basic conductive theory of hydrogels, which can be divided into the hydrogel structure and zwitterionic enhancing conductivity theories. We then classify polyelectrolyte-based conductive hydrogels into different types, including double, ionic-hydrogen bond, hydrogen bond，and physically crosslinked networks. Furthermore, the mechanical, electrical, and self-healing properties and fatigue and temperature interference resistance of polyelectrolyte-based conductive hydrogels are described in detail. We then discuss their versatile applications in strain sensors, solid-state supercapacitors, visual displays, wound dressings, and drug delivery. Finally, we offer perspectives on future research trends for polyelectrolyte-based conductive hydrogels.

A review: flexible devices for nerve stimulation

“…Furthermore, room-temperature liquid metals (LM) possess good fluidity and excellent electrical conductivity, making them suitable for long-term neurostimulation applications. For instance, Tang et al developed fluid cuff electrodes that utilize gallium-based LM conductors to achieve long-term stimulation of peripheral nerves [31] .…”

Recent developments of polysaccharide‐based double‐network hydrogels

“…Highly hydrated hydrogels containing intrinsically conductive electroactive materials show excellent properties as a combination of their constituents 181 . The conductive hydrogels can transform the external stimuli into electrical signals, which can be used in the fields of tissue engineering, artificial skin, and flexible sensors 182,183 .…”

“…(A) Illustration of the main strategies to prepare conductive hydrogels. Reproduced with permission 181 . Copyright Elsevier 2019 (B) electrically conductive Ag flakes‐Alg/PAAm composite hydrogel.…”

“…Highly hydrated hydrogels containing intrinsically conductive electroactive materials show excellent properties as a combination of their constituents. 181 The conductive hydrogels can transform the external stimuli into electrical signals, which can be used in the fields of tissue engineering, artificial skin, and flexible sensors. 182,183 As shown in Figure 18A, conductive PDN hydrogels are classified namely into three categories regarding the additives: Nanoparticles-based (e.g., MXene, metal, and carbon), conductive polymer-based (e.g., PANI, PEDOT, and PPy), and electrolyte/polyelectrolyte-based conductive hydrogels.…”

“…Reproduced with permission. 181 Copyright Elsevier 2019 (B) electrically conductive Ag flakes-Alg/PAAm composite hydrogel. Reproduced with permission.…”