Magnetoelectric BaTiO3/CoFe2O4 Thin-Film Meshes for Neuronal Differentiation.

Magnetoelectric composites offer a powerful route for remotely converting magnetic stimuli into local electrical cues, with promising biomedical applications in electrical stimulation. In strain-mediated magnetoelectric heterostructures, however, efficient coupling depends strongly on crystallinity, interface quality, and mechanical boundary conditions. Epitaxial thin films provide excellent crystallinity and well-defined interfaces, but substrate clamping suppresses strain transfer and limits magnetoelectric performance. Here, we report a freestanding magnetoelectric mesh based on an epitaxial BaTiO3/CoFe2O4 bilayer and demonstrate its use for magnetic-field-driven neural progenitor cell differentiation. By systematically relaxing the mechanical boundary condition from substrate-clamped films to polydimethylsiloxane (PDMS)-transferred structures and ultimately to freestanding meshes, we show a progressive enhancement in the magnetoelectric coupling coefficient. This enhancement is directly reflected in improved neural progenitor differentiation, establishing magnetoelectric transduction as a key driver of the observed cellular response. Our results show that engineering mechanical compliance in epitaxial magnetoelectric platforms can substantially improve biofunctional stimulation, providing a design strategy for next-generation cell culture, differentiation, and wireless stimulation systems.