Bioinspired asymmetric structural synergy for soft robotics: closed-loop piezoelectric harvesting and ionic actuation

Conventional robotics face fundamental trade-offs among energy-autonomy, actuation efficiency, and manufacturing simplicity. Here, we break this dilemma through a universal material design strategy of “bioinspired asymmetric engineering”. This concept is materialized through a one-step, scalable coordination of metal-organic framework UIO-66(Hf) with a piezoelectric polymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)), yielding a hierarchical hemispherical-pore composite that achieves record piezoelectricity (d33 = 46.7 ± 0.4 pC/N), and generating considerable piezoelectric outputs (open-circuit voltage (Voc) = 32.0 V, short-circuit current (Isc) = 2.2 μA, Power density (PD) = 10.9 μW cm−2). The same asymmetry principle enables a Janus actuator, where programmed elastic modulus gradation and porous ion channels co-produce ultrafast response (0.8 ms) and large bending (18.0 mm). Crucially, we first demonstrate the strategy’s versatility by integrating these components into a closed-loop, and self-powered robotic system capable of direct piezopotential-driven actuation. This work establishes asymmetric structural design as a versatile materials paradigm, opening the pathways toward intelligent soft robotics and autonomous embodied systems.