Liquid Metal Direct Write and 3D Printing: A Review

Abstract This review discusses methods, challenges, and opportunities for direct‐write and 3D printing of low melting point, gallium‐based liquid metal alloys at room temperature. Alloys of gallium exhibit high conductivity and high stretchability making them well suited for use in soft circuitry for stretchable electronics and soft robotics. In addition, the liquid nature of the metal enables entirely new ways to pattern metals at room temperature; herein, the focus is placed on additive printing via nozzle‐based methods. Room temperature printing of liquid metals enables rapid fabrication of complex geometries (with dimensions as small as 10 µm) on a wide range of materials, such as polymers. These processes can be used to make metallic conductors for devices with self‐healing capabilities, soft/stretchable electrodes, and sensors.