One‐Step Direct Writing and In Situ Poling of Ultrathin Piezoelectric Microarchitectures for Organ‐Conformal Stretchable Biointerfaces

The development of ultrathin, stretchable piezoelectric biointerfaces is fundamentally constrained by the lack of manufacturing strategies capable of simultaneously delivering precise microarchitectural patterning and stable polarization in mechanically compliant formats. Here, we report a one‐step electrohydrodynamic (EHD) direct‐writing strategy with in situ poling, enabling the concurrent fabrication and polarization of free‐standing, ultrathin piezoelectric microarchitectures without post‐processing. By coupling this manufacturing approach with a mechanism‐guided design based on thermoplastic polyurethane (TPU) and piezoelectric P(VDF‐TrFE) through controlled modulation of EHD deposition and polymer crystallization, we manipulate grain size and flatten the polarization barrier by introducing structural heterogeneity to achieve a high and stable piezoelectric coefficient of 34.5 pm V −1 in a highly stretchable architecture. The resulting sub‐20 µm serpentine microarchitectures exhibit excellent mechanical compliance, long‐term piezoelectric stability and deterministic architectural programmability. Integration with a breathable, controlled‐adhesion elastomeric biointerface ensures robust conformal coupling to soft, wet tissue. Ex vivo demonstrations validate reliable detection and classification of gastric mechanical states, highlighting a manufacturing‐enabled platform for organ‐conformal piezoelectric biointerfaces. This work offers a generalizable strategy to overcome long‐standing trade‐offs between piezoelectric performance, stretchability, and ultrathin form factors, paving the way for diverse applications in biointegrated electronics and soft sensing, and healthcare systems.