Programming Actuation in 3D‐Printed Micro‐Architectures via Interfacial Adhesion Control

ABSTRACT Bilayer structures drive anisotropic deformation in stimuli‐responsive actuators, but their precise manufacturing remains challenging. Here, we report a two‐phase meniscus‐guided 3D printing method to directly fabricate microscale bilayer structures with in situ programmable interfaces. By modulating the meniscus stretching speed, we control the interfacial bonding between poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(vinyl alcohol) (PVA). We systematically mapped the critical pulling speed governing the transition from physically separated to seamlessly bonded bilayers across 5%–30% relative humidity (RH) and varying ink concentrations (0.5–2.0 wt.% PVA, 0.18–0.70 wt.% PEDOT:PSS). The bonded architectures demonstrated excellent stability, remaining intact without delamination for 72 days at 40% RH. This in situ structural programming dictates the mechanical actuation under environmental stimuli. Fully bonded structures exhibited robust reversible bending under cyclic RH fluctuations (20%–50%). Furthermore, the structures displayed a deterministic thermal response, with the bending angle systematically increasing from 11.2° to 15.1° between 40°C and 65°C. Under non‐contact infrared (IR) irradiation, the micro‐actuators maintained high‐frequency oscillation with a 0.6° amplitude over 250 cycles. By controlling interfacial adhesion through physical printing parameters, this approach spatially programs actuation, providing a practical framework for multi‐responsive soft robotics.