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Page 34 of 47 Zhou et al. Soft Sci. 2026, 6, 10

bending, and sweat exposure is critical. Combining various biomaterials with integrated wireless
transmission modules allows tailoring treatment plans for different diseases, facilitating telemedicine and
data-driven therapy. This technology is poised to play a greater role in personalized medicine, smart
dressings, implantable devices, and related fields .
[197]

MEGT wearable energy technology is transitioning from a phase of basic material exploration toward higher
goals of efficiency, stability, and multi-application capabilities. However, low power density, strong
dependence on environmental humidity, and insufficient long-term stability of materials and interfaces limit
the practical application of MEGT devices in commercialization and wearable fields. The primary reason for
these performance limitations lies in the reliance of energy harvesting on the chemical potential energy of
water molecule diffusion. At the same time, inherent material-level constraints also affect energy density.
Functional layer mechanisms exhibit varying sensitivity to ambient humidity: low humidity results in
insufficient ion concentration, whereas high humidity diminishes the chemical potential gradient. Long-term
operation further contributes to irreversible performance degradation through polymer substrate hydrolysis,
oxidation and agglomeration of functional materials, and delamination at electrode interfaces.

CHALLENGES
Ideal MEGTs integrate multiple functions, such as energy self-sufficiency, signal sensing, flexibility, and
biodegradability. However, current technology remains constrained by low power density and bottlenecks in
process stability, long-term reliability, and arrayed manufacturing. To advance development toward
high-performance, low-cost, large-scale production, and broad applications - and to propel practical
implementation in smart electronic textiles - it is essential to systematically address the following four
challenges.

High performance and low cost
How to significantly reduce manufacturing costs while maintaining high output power, high energy density,
and long-term stability remains a core challenge restricting the practical implementation of MEGTs. Table 2
summarizes the performance parameters of several MEG devices. It can be seen that various materials are
used in the electric generation layer, with research most concentrated on 2D configurations. The power
density of existing devices is insufficient to drive high-power electronics directly, although performance can
be enhanced through device integration. The effective reaction area of a single fiber is small, and the ion
migration gradient is limited, leading to low V and current density. Additionally, transient fluctuations in
oc
ambient humidity and temperature significantly affect output stability. If the moisture absorption-desorption
cycle is unbalanced, water content tends to saturate, the ion gradient dissipates, and power generation ceases.
Intrinsic limitations on power output arise from finite ion concentration within the power generation layer,
slow ion migration through nanoscale channels, and high internal resistance. These factors collectively
constrain device current and power. Long-term stability is challenged by repeated swelling and shrinkage
during moisture absorption and drying cycles, which can induce structural fatigue and failure. Irreversible
consumption of active ions and chemical degradation of materials also contribute to performance decline.
Breaking the power bottleneck is fundamental to driving electronic devices, while resolving stability issues is
critical to ensuring practical application. Device cost is mainly determined by material selection,
manufacturing processes, and assembly. High-cost or brittle materials are prone to uneven thickness, cracks,
wrinkles, and other defects during large-area spinning, coating, or printing, deteriorating performance
output. Therefore, under the premise of high performance, process complexity should be reduced and costs
controlled, enabling economical, large-scale fabrication of high-performance devices.

In the development of MEGT devices, low power density constitutes the core bottleneck for practical
applications, constrained by both the energy characteristics of environmental moisture and the intrinsic