Interface-governed electromechanical coupling in bioinspired hierarchical piezoelectric poly(L-lactide) architectures

Bioinspired materials frequently derive functionality from hierarchical organization and chemically active interfaces that mediate the conversion of mechanical stimuli into biological signals. Emulating such interface-governed mechanotransduction in synthetic soft matter remains a major challenge for electromechanical biomaterials. Here, we introduce a hierarchical piezoelectric polymer architecture in which plasma-engineered interfaces act as active functional elements that govern ultrasound-driven electromechanical coupling. Two piezoelectric poly(L-lactide) (PLLA) layers with distinct morphologies-a uniaxially drawn film and an electrospun fibrous mat-are directly bonded via plasma-assisted surface activation, enabling morphologically well-integrated and strong interfacial adhesion without additional adhesive phases. Under ultrasound excitation, mechanical energy is preferentially concentrated at the chemically activated interface, generating enhanced shear deformation and a synergistically amplified piezoelectric response that exceeds the performance of the individual layers. This interface-dominated electromechanical coupling translates efficiently to biological systems through an extracellular-matrix-mimetic fibrous surface, enabling effective transfer of electrically mediated cues to adherent cells. Ultrasound-activated piezostimulation of human keratinocytes demonstrates enhanced cell adhesion, proliferation, and cytoskeletal organization. By establishing chemically programmed interfaces as a new design axis for electromechanical energy transduction, this work defines a bioinspired materials chemistry paradigm for adaptive piezoelectric surfaces and interfaces with broad relevance to bioelectronics, regenerative medicine, and dynamic tissue engineering.