采用可编程液滴包裹体对3D打印弹性体进行按需调制

One of the key thrusts in three-dimensional (3D) printing and direct writing is to seamlessly vary composition and functional properties in printed constructs. Most inks used for extrusion-based printing, however, are compositionally static and available approaches for dynamic tuning of ink composition remain few. Here, we present an approach to modulate extruded inks at the point of print, using droplet inclusions. Using a glass capillary microfluidic device as the printhead, we dispersed droplets in a polydimethylsiloxane (PDMS) continuous phase and subsequently 3D printed the resulting emulsion into a variety of structures. The mechanical characteristics of the 3D-printed constructs can be tuned in situ by varying the spatial distribution of droplets, including aqueous and liquid metal droplets. In particular, we report the use of poly(ethylene glycol) diacrylate (PEGDA) aqueous droplets for local PDMS chemistry alteration resulting in significant softening (85% reduced elastic modulus) of the 3D-printed constructs. Furthermore, we imparted magnetic functionality in PDMS by dispersing ferrofluid droplets and rationally designed and printed a rudimentary magnetically responsive soft robotic actuator as a functional demonstration of our droplet-based strategy. Our approach represents a continuing trend of adapting microfluidic technology and principles for developing the next generation of additive manufacturing technology. SignificanceTo manipulate extruded ink composition and properties in real time, we demonstrate the concurrent generation and deposition of textured inks with droplet inclusions. Dispersing different fluids into droplets within PDMS, we demonstrate the ability to locally impart function at the point of print, either by chemical modification resulting in mechanical compliance or by using functional nanoparticle suspensions that respond to external stimulus (e.g., B field). The present study thus introduces a strategy for facile fabrication of heterogeneous and functional structures.