MME researchers publish paper outlining printing process for liquid metal droplets

The "On Demand Programming of Liquid Metal-Composite Microstructures Through Direct Ink Write 3D Printing" is outlined in a paper co-authored Eric Markvicka, assistant professor of mechanical and materials engineering, and Aaron Haake, senior in mechanical and materials engineering and published in the March 30 edition of the journal Advanced Materials.

Working in Markvicka's Smart Materials & Robotics Lab, the team developed a process of creating soft, elastically deformable composites with liquid metal (LM) droplets that can enable new generations of soft electronics, robotics, and reconfigurable structures. These printed materials are soft, higly deformable, and can be made locally insulating or electrically conductive using a single ink by controlling process conditions.

Markvicka's team demonstrated these capabilities by embedding elongated LM droplets in a soft heat sink, which rapidly dissipates heat from high-power LEDs.

These programmable microstructures can enable new composite paradigms for emerging technologies that demand mechanical compliance with multifunctional response.

Previously, techniques to control local composite microstructure, which ultimately governs material properties and performance, were lacking. Markvicka's team developed a direct ink writing technique to program LM microstructure (i.e., shape, orientation, and connectivity) on demand through elastomer composites. This is in constrast to inks with rigid particles that have fixed shapes and sizes.

The new technique enables filaments, films and 3D structures with unique LM microstructures that are generated on demand and locked in during printing. This includes smooth and discrete transitions from spherical to needle-like droplets, curvilinear microstructures, geometrically complex embedded inclusion patterns, and connected LM pathways.

The other co-authors on the paper were Michael Bartlett, Gwyneth Schloer and Ravi Tutika from the Soft Materials and Structures Lab at Virginia Tech.