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Zhou et al. Soft Sci. 2026, 6, 10 Page 7 of 47

Table 1. Comparison of streaming potential mechanism and ion diffusion mechanism
Mechanism Streaming potential Ion diffusion

Core principle Liquid flow drives ion movement Ion diffusion under chemical potential gradient
Material characteristics Nanochannels, porous structures Asymmetric hygroscopic structure
Output characteristics Responsive, affected by fluid flow High stability, long duration
Advantages Stable output power, high current Simple device structure, easy to integrate, high voltage
Disadvantages Dependent on water flow or evaporation Dependent on ambient humidity

enhances the ion concentration gradient, promoting more directed ion movement and ultimately increasing
voltage output. By synergistically regulating the materials and structures of the moisture-absorbing layer and
electrodes, the water-ion gradient can be fully leveraged to enhance both device performance and stability.

Humidity is the core factor affecting ion migration and energy conversion efficiency. It underlies the
formation of internal moisture gradients, which promote the dissociation of functional groups to produce
free ions, establish ion concentration gradients, drive directional ion migration, and enhance energy
conversion efficiency . Humidity fluctuations can destabilize ion migration pathways, impairing charge
[45]
separation efficiency. This dependence on external humidity in conventional devices can be mitigated by
maintaining an internal humidity gradient through asymmetric structures . Elevated temperatures
[88]
accelerate the thermal motion of ions, enhancing their diffusion, but excessively high temperatures may
damage material structures or cause rapid water evaporation, reducing the humidity gradient and thereby
decreasing energy output. The influence of the physicochemical properties of the power generation layer on
device performance has been discussed previously. Additionally, asymmetric electrode structures and robust
electrode–layer interfaces promote directed ion migration , while highly conductive electrode materials
[89]
reduce electrical resistance, further enhancing device energy output.

Streaming potential and ion diffusion are the two core mechanisms of MEG. Table 1 summarizes the key
differences between them. The streaming potential mechanism converts mechanical energy into electrical
energy by relying on pressure gradients to drive fluid movement within electrically charged nanochannels .
[45]
The viscous drag of counterions in the EDL generates flow currents, requiring an external or built-in
pressure field to achieve sustained and stable electrical energy output . In contrast, the ion diffusion
[65]
mechanism arises from the dissipation of chemical potential gradients, enabling the direct conversion of
chemical potential energy into electrical energy. Here, ions (H ) ionized by hydration undergo directed
+
diffusion along the concentration gradient, establishing a diffusion potential [18,35] . This mechanism does not
require external mechanical input and can harvest energy under static humidity conditions; however, its
output typically exhibits transient or relaxation behavior and is sensitive to dynamic environmental humidity
changes . High-performance MEG devices can be optimized by leveraging the combined effects of both
[12]
mechanisms.

FUNDAMENTAL MATERIALS OF MOISTURE ELECTRIC GENERATION TEXTILES
Electric-generating materials form the core of humidity-powered devices, producing electrical output
through water absorption, functional group dissociation, and ion migration. Consequently, ideal
power-generating materials should combine high hygroscopicity, excellent ionic conductivity, and robust
stability to ensure efficient and reliable device performance. The large specific surface area and 3D porous
structure of textiles provide an excellent platform for maximizing the active interface of moisture-absorbing
functional materials [90,91] . This allows nanoscale properties to be fully realized in macroscopic fabrics,
significantly enhancing energy capture efficiency and output capacity . Based on material type, these
[92]