High-resolution, reconfigurable printing of liquid metals with three-dimensional structures

TLDR

The study introduces a high‑resolution, reconfigurable 3D printing technique that employs liquid metals to create stretchable, three‑dimensional integrations. Direct printing of liquid metals produces 1.9 μm lines that can be reconfigured into diverse 3‑D structures. The printed lines achieve a minimum width of 1.9 μm, can be repeatedly reconfigured, and the resulting thin oxide interface preserves electrical properties, enabling applications such as tunable antennas, mechanical switches, and densely integrated microLED arrays.

Abstract

We report an unconventional approach for high-resolution, reconfigurable 3D printing using liquid metals for stretchable, 3D integrations. A minimum line width of 1.9 μm can be reliably formed using direct printing, and printed patterns can be reconfigured into diverse 3D structures with maintaining pristine resolutions. This reconfiguration can be performed multiple times, and it also generates a thin oxide interface that can be effective in preventing the spontaneous penetration of gallium atoms into different metal layers while preserving electrical properties under ambient conditions. Moreover, these free-standing features can be encapsulated with stretchable, conformal passivations. We demonstrate applications in the form of a reconfigurable antenna, which is tunable by changing geometeries, and reversibly movable interconnections used as mechanical switches. The free-standing 3D structure of electrodes is also advantageous for minimizing the number and space between interconnections, which is important for achieving higher integrations, as demonstrated in an array of microLEDs.