Biomimetic Microfractals Based Flexible Triboelectric Nanogenerators

Flexible TENGs are promising for self-powered wearables, but combining high output, mechanical compliance, and low material use remains challenging. Here, we report a biomimetic microfractal TENG (BM-TENG) inspired by leaf-skeleton vascular architectures, where the hierarchical network serves as both porous current-collector scaffold and template for triboelectric surface replication. Copper nanowires immobilized along the microfractal pathways form guided and locally bundled conductive networks, enabling a low sheet resistance of ∼15 Ω sq−1 and >1000 fold reduction in sheet resistance compared with a planar control. Replication of the same architecture into electrospun Nylon-6 and PVDF layers creates a compliant multiscale topography that enhances charge generation. The BM-TENG delivers ∼52 V open-circuit voltage, ∼3.2 µA short-circuit current, and ∼67.24 nC transferred charge per cycle while using 50% lower CuNW loading, compared with ∼26 V, ∼1.23 µA, and ∼27.35 nC for the planar control. Using projected device area as the primary normalization basis, BM-TENG achieves a current density of ∼3 mA m−2 and power density of ∼136.91 mW m−2, compared with ∼1.13 mA m−2 and 135.80 mW m−2 for the planar control. As secondary metrics, effective-material-area normalization gives ∼10 mA m−2 and ∼456.35 mW m−2 for the BM-TENG. The device also maintains stable output over ∼10000 cycles.