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Page 8 of 57 Zheng et al. Soft Sci. 2026, 6, 32

tensile strength of 791.7 MPa in hydrospun fibers without additives .
[50]
Traditional disordered crystalline-amorphous structures and naturally occurring crystalline-amorphous
superstructures, as seen in Figure 3B, indicate how adding ordered nanostructures can synergistically
improve mechanical properties in fiber structural design. Li et al. created graphene-based fibers with high
strength and high toughness by in-situ growing an amorphous coating over crystalline GO sheets, drawing
inspiration from the “brick-and-mortar” structure of nacre . During tensile loading, the micro-wrinkled
[61]
surface structure efficiently releases energy through a “wrinkle extension” process, allowing the fiber to attain
a high toughness of 10.6 MJ·m and a high strength of 935 MPa. Figure 3C illustrates how the fiber
-3
microstructure changes during stretching. By controlling the size of liquid crystal domains, another “domain
folding” technique reduces structural flaws brought on by layer curling and inadequate stacking at the source
by causing GO sheets to form highly folded yet densely interconnected nanostructures . Many interface
[19]
enhancement techniques have been used extensively to improve stress transfer between nanosheets. Fiber
ductility and load-bearing capacity can be greatly increased by ionic crosslinking, such as by adding Ca or
2+
ethylenediamine, which can improve interlamellar contacts during plasticization . Covalent crosslinking
[51]
uses chemical interactions, such as amidation reactions between aromatic amines and carboxyl groups at GO
edges, to connect layers [Figure 3D and E]. By creating extended conjugated systems, this method not only
increases the tensile strength of the fiber but also greatly improves electrical conductivity . Moreover,
[63]
topological limitations act as a mechanism for physical reinforcement. Polymer chains create physical
crosslinking networks that efficiently improve stress transfer by passing through the pores of porous
graphene sheets [Figure 3F-I] .
[62]

A crucial post-treatment step for improving the performance of GFs is high-temperature thermal reduction.
By efficiently eliminating oxygen-containing functional groups, reestablishing the sp -hybridized carbon
2
network, and decreasing interlayer spacing, this procedure enhances the fiber’s mechanical and electrical
conductivity. High-performance GFs with tensile strengths up to 2.2 GPa and Young’s moduli of 400 GPa
have been successfully manufactured by optimized thermal reduction techniques , as shown by their
[17]
macroscopic and microscopic morphologies in Figure 3J and K. However, compared to commercial
high-performance carbon fibers, the strength and modulus of modern GFs are still typically lower. Grain
boundaries that are challenging to totally eradicate, sheet creases, and intrinsic structural flaws in the GO
precursor are important limiting constraints. Notably, the majority of current research has concentrated on
attaining exceptionally high modulus and tensile strength. However, it is essential to give nanosheets
exceptional toughness, fatigue resistance, and long-term durability while retaining high strength for wearable
smart textile applications. Three-dimensional graphene networks’ toughening and reinforcing methods
could serve as an inspiration for future studies. It may be possible to improve the strength, flexibility, and
service stability of one-dimensional dense fibers by investigating how to apply these principles which allow
for superelasticity, high fatigue life, and exceptional toughness to the production process [64,65] .

Electrical properties
Conductivity testing conditions: Unless otherwise noted, the four-probe method was usually used to measure
conductivity values presented in this section at ambient temperatures (25 °C, 40%-60% relative humidity).
The associated circumstances are described in detail in the original sources and quickly summarized in the
pertinent discussion sections for fibers measured under particular conditions (such as vacuum, post-doping,
or cryogenic settings).

The capacity of graphene-based fibers to carry out circuit connectivity, signal transmission, sensing, and
energy storage tasks is largely dependent on their high electrical conductivity. The conductivity of
macroscopic graphene-based fibers is limited by interlayer contact resistance, structural flaws, and