Conductive gels are mainly composed of conductive components and matrix materials. Based on type, they can be classified as follows:
Conductive Hydrogels: Use hydrophilic polymers (such as polyvinyl alcohol, chitosan, sodium alginate) as a framework, contain a large amount of water, and introduce ionic or electronic conductive media.
Ionic Conductive Hydrogels: Achieve conductivity by dissolving salts (such as NaCl, LiCl) or ionic liquids, relying on ion migration to conduct current.
Electrically Conductive Hydrogels: Achieve electronic conduction by incorporating conductive nanomaterials (such as carbon nanotubes, graphene, metal nanoparticles) or conductive polymers (such as polyaniline, polypyrrole, PEDOT:PSS).
Example: The conductivity of GelMA-based conductive hydrogels can be improved by loading graphene or polyaniline.
Metal Gels: Using liquid metals (such as gallium and gallium-indium alloys) as the conductive fluid, immobilized within a polymer network, these gels exhibit an electronic conductivity as high as 3.18 × 10⁶ S·m⁻¹, approaching that of traditional metals, while also possessing a low Young's modulus (70 kPa) and high flexibility.
Ionic Gels: Composed of polymers (such as polyacrylic acid and polyvinyl alcohol) and ionic liquids or electrolytic salts, these gels possess ionic conductivity and a spatial network structure, making them suitable for flexible sensors and biomedical applications.
Conductive Organic Hydrogels: Constructed through solvent exchange (such as a glycerol/water system) and mechanical training to create multi-level oriented structures, these gels maintain flexibility and conductivity (0.64 S·m⁻¹) even at -80°C, making them suitable for sensing in extremely cold environments.
Conductive Silver Paste: Using thermosetting adhesives such as epoxy resin as a matrix, filled with silver ions as the main conductive component, these gels exhibit excellent conductivity and are commonly used for electronic connections.