Curvature-adaptive low-temperature metallization for flexible and conformal electronics enabled by rheology-driven acoustic coupling

Achieving reliable metallization on curved and mechanically diverse substrates remains challenging because conventional post-printing sintering methods often produce non-uniform energy delivery, incomplete particle necking, and unstable electrical performance. Here, we report a low-temperature ultrasonic sintering strategy using a shear-thickening fluid-filled flexible bladder to improve conformal contact and rheology-regulated acoustic–mechanical coupling. Under combined external loading and ultrasonic excitation, the bladder transitions from a compliant state to a stiffened coupling state, promoting pressure transfer and ultrasonic energy delivery to printed silver nanoparticle films. Within 3 s of ultrasonic activation, the process produced dense conductive films with a conductivity of 2.51 × 10⁵ S cm⁻¹. The method was demonstrated on representative curved, rough, and flexible substrates, including UV-curable resins, eggshells, and polyimide films. When combined with five-axis conformal inkjet printing, the approach enabled continuous conductive patterns with low spatial variation across the tested non-planar geometries. These results provide a promising route for low-temperature metallization of flexible and conformal electronic structures.