Programmable pulsed aerodynamic printing for multi-interface composite manufacturing

Droplet-based printing is increasingly popular for flexible sensors, soft robotics, bioprinting, and bioinspired structures. However, programmable multi-interface droplet printing with a wide Z number (reciprocal of the Ohnesorge number) remains challenging. We present a method, programmable pulsed aerodynamic printing (PPAP), for patterning soft materials with extensive material compatibility and multi-scale and multi-interface properties. PPAP utilizes programmable pulsed airflow to shear pendant droplets at the nozzle orifice, covering a broad range of parameter domains. Owing to its co-flow configuration, PPAP can accurately print droplets with shell-core, Janus, and combined morphologies. The multi-interface droplet size is independent of its physicochemical parameters and can be predicted by the scaling law. Demonstrations include multi-scale, multi-interface composites: cell-loaded annular particles, liquid metal circuits, laser stimuli-responsive microcapsules, calcium alginate elastomers, and 3D multi-interface clusters. PPAP may promote the development of micro-nano functional structures and devices.