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Zhou et al. Soft Sci. 2026, 6, 10 Page 23 of 47

Electrospinning uses a high-voltage electric field to produce nanofiber films with high specific surface area
and porous structures, enhancing ion transport. As a power generation layer material, nanofiber films
prepared by electrospinning exhibit high moisture absorption capacity and excellent electrical properties.
Sun et al. applied electrospun polymer nanofiber fabrics to wearable MEGTs, in which PEO nanofiber fabrics
provided a high output voltage of 0.83 V and excellent air permeability . In Figure 11C, Sun et al. prepared
[168]
a nanofiber film containing electrolyte from PAN/SDBS solution [169] . This device could continuously and
stably output a voltage of 0.7 V and a current of 3 mA for 120 h, demonstrating outstanding stability and
durability. By optimizing its structure, Zhang et al. introduced a CA nanofiber film with a tree-like structure
obtained by electrospinning [170] . A single device generated approximately 700 mV, with a maximum output
power density of 2.45 μW·cm . Sun et al. employed coaxial conjugate electrospinning to form a core-shell
-2
structure by winding PAN nanofibers around a zinc wire [171] . The PAN nanofibers provide a high specific
surface area and porous structure, while the zinc wire core electrode ensures good conductivity.
Subsequently, as shown in Figure 11D, Hu et al. successively deposited PAN and poly(vinylidene
fluoride-trifluoroethylene) [P(VDF-TrFE)] nanofibers onto a cellulose nonwoven (CNW)/LiCl layer via
electrospinning, constructing a multi-layer fabric structure with unidirectional moisture conductivity .
[49]
Owing to the structure and material properties of the nanofiber layer, the device operates stably across
15%-80% RH and -10 to 55 °C.

Coating technology
Spraying, drop-casting, and impregnation methods can be used for large-area preparation of power
generation layers. The spraying method is fast and uniform; drop casting allows the solution to diffuse
naturally by capillary action, and impregnation immerses the substrate in solution. These methods are
convenient for integrated design, and the uniformity and performance of the power generation layer can be
optimized by controlling process parameters. Wang et al. used casting and spraying strategies to combine a
PDDA layer with a PSSA layer to prepare a BPF [Figure 12A] [105] . The material exhibits good mechanical
flexibility along with high voltage output and maintains excellent performance and stability even under
bending or pressing. Poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) can form a network-like
support structure in a nano-alumina composite film. Yao et al. therefore used patterned coating technology
to prepare devices with a nano-alumina self-supporting film as the power generation layer [Figure 12B] [172] .
This method allows the simultaneous fabrication of hundreds of series and parallel devices, enabling scalable
and customizable output voltage and current. As shown in Figure 12C, Zhu et al. evenly coated protein
dispersion with an adjusted pH onto a substrate by a scraping method and dried it to form a protein film
power generation layer . The protein film exhibits self-healing ability, and its electrical output can be
[40]
restored after scratches through water treatment. The thickness of the power generation layer is controlled by
repeated dip-coating, allowing the electric output to be tuned by humidity changes. Gao et al. immersed
pretreated cotton yarn in a PSSA/PVA solution [129] . Using a spinning machine, they produced
high-performance MEGTs with radial PSSA/PVA gradients under centrifugal force [Figure 12D]. This
structural design maintains a continuous moisture gradient between the yarn’s interior and exterior, while
the use of PSS and aluminum electrodes enhances proton diffusion efficiency. Shao et al. explored a coaxial
fiber based on GO material, in which a silver wire was immersed in GO suspension, allowing GO to adhere
to its surface . Later, He et al. developed a double asymmetric structure MEGT to optimize electrical output
[52]
by varying the soaking time [141] . The device exhibits high flexibility, large-scale integrability, strong
environmental adaptability, and a simple, low-cost preparation process, making it suitable for large-scale
production and applications.

Manufacturing of electrodes
Electrodes need to provide electrical conductivity and strong adhesion to the power generation layer.
Screen-printing and digital manufacturing technologies are important methods for achieving large-area