Researchers from Lanzhou University, University of Science and Technology Beijing and the Chinese Academy of Sciences (CAS) have developed a new class of hollow graphene aerogel fibers (GAFs) inspired by the ultra-efficient thermal insulation of polar bear hair. By translating nature’s design into a scalable, coaxial-extrusion-spinning process, the team achieved a multifunctional fiber that sets records for both electrical conductivity and thermal insulation, paving the way for next-generation smart textiles.
Each fiber features a hierarchically porous, hollow structure, closely mimicking the air-trapping tubes of polar bear fur. During fabrication, graphene oxide (GO) nanoplates in the outer spinning channel self-assemble under shear stress into an arch-like microstructure, while a removable core material shapes the central cavity. After a hydrothermal reduction and high-temperature annealing - up to 2000 °C - the resulting structure combines low density with tunable electro-thermo-mechanical properties.
At an annealing temperature of 2000 °C and GO ink concentration of 20 mg/mL, the fibers reached an electrical conductivity of 1457.09 S/m, among the highest reported for any aerogel fiber, alongside an ultralow thermal conductivity of 1.28 mW/(m·K) under vacuum - a record for graphene-based aerogels, as was claimed. The low thermal conduction arises from intense phonon scattering within the multiscale porous network and the winding heat paths enforced by its hollow, layered structure. Meanwhile, the intrinsic defects and oxygen groups introduced during processing suppress thermal transport while maintaining electronic conductivity, balancing two normally conflicting objectives.
Mechanically, the fibers behave like elastic springs: they recover 90% strain after heavy compression and endure repeated 80% strain cycles with minimal degradation. Their resilience and conductivity make them ideal components for flexible, wearable electronics. Integrated into textile form, these GAFs operate as motion sensors (via the piezoresistive effect), thermoelectric generators (Seebeck coefficient 16.7–20.0 µV/K), and adaptive heaters, capable of reaching 175 °C at just 7 V while remaining within human-safe voltage limits.
Beyond sensing and heating, the textiles show exceptional insulation and infrared stealth. Tests comparing the graphene aerogel fabric with polystyrene, asbestos board, silica aerogel blanket, and wool demonstrated over 20% higher insulation efficiency. In thermal imaging, the fabric drastically reduced IR visibility when covering hot machinery, underlining potential for camouflage and protective clothing. Remarkably, the same fibers also shielded skin from liquid nitrogen at -196 °C and stabilized lithium battery performance in both extreme heat and cold.
The researchers attribute this multifunctionality to the synergy of atomic-scale disorder and macroscopic structuring - defects tune the electronic and thermoelectric behavior, while the porous geometry governs mechanical and thermal properties. With its combination of high elasticity, conductivity, and insulation, the polar-bear-hair-inspired graphene aerogel fiber represents a promising platform for intelligent perception, energy harvesting, and thermal management, potentially transforming wearable electronics and thermal protection systems in both civilian and defense fields.
