The Wing of Nephrotoma appendiculata as a Natural Microsystem: Observation, Simulation, and Its Inspiration for Micro-Air-Vehicle Wing Design

This study investigates the morphological and biomechanical characteristics of Nephrotoma appendiculata (NA) wings, identifying a sophisticated, multifunctional fractal-like venation system optimized for balancing flight stability and impact resilience. Unlike conventional studies that focus on common models such as dragonflies or bees, this work highlights NA as an exceptional biomimetic model due to its superior yaw control, low flapping frequency (30–50 Hz) for stealth, and high energy efficiency. Using optical microscopy, scanning electron microscopy (SEM), mass measurements, and mechanical testing, we characterized the gender-specific morphology, geometry, mass distribution, and other key features of NA wings, and analyzed the anisotropic properties of their tapered veins and corrugated membranes. Furthermore, both analytical and finite element analyses were performed to examine the passive torsional behavior of tapered versus untapered veins. The results indicate that tapered veins significantly reduce twist angles and bending displacements under micro-Newton scale loads. Unlike previous studies focusing on frontal impacts, this research highlights a defense mechanism against dorsal and ventral disturbances, where tapering minimizes displacement transmission to the critical wing root (radial stop region). Our strain-energy models indicate that tapered veins significantly reduce twist angles and restrict the concentration of strain energy near the proximal root under micro-Newton loads, suggesting a mechanism to mitigate impact-induced disturbance transmission. These findings imply that the tapered venation system may represent an evolutionary trade-off, using limited material to create a structure that is rigid enough for stable flight yet resilient enough to absorb damaging impacts—an optimization strategy that could contribute to survival.