On-Demand Programming of Liquid Metal-Composite Microstructures through Direct Ink Write 3D Printing.

Area of Science:

• Materials Science
• Soft Matter Physics
• Additive Manufacturing

Background:

• Soft, deformable composites with liquid metal (LM) droplets are crucial for soft electronics and robotics.
• Existing methods lack control over the local composite microstructure, limiting material properties and performance.

Purpose of the Study:

• To develop a technique for programming the LM microstructure within elastomer composites on demand.
• To demonstrate control over LM shape, orientation, and connectivity for tailored material properties.

Main Methods:

• A direct ink writing technique using emulsion inks with LM fillers was developed.
• In situ control of LM microstructure was achieved by manipulating printing process conditions.
• The technique allows for the creation of filaments, films, and 3D structures with programmable microstructures.

Main Results:

• Demonstrated on-demand programming of LM microstructure, including transitions from spherical to needle-like droplets and curvilinear patterns.
• Achieved control over the electrical conductivity of the composite materials, enabling locally insulating or conductive regions.
• Printed materials exhibit high softness (modulus < 200 kPa) and deformability (>600% strain).

Conclusions:

• The developed direct ink writing technique offers unprecedented control over LM microstructure in soft composites.
• Programmable microstructures enable new composite paradigms for technologies requiring mechanical compliance and multifunctionality.
• Applications include soft heat sinks for efficient thermal management in electronics.