3D Printed Liquid-Filled Metal Microarchitectures

Abstract

Encapsulation of liquids within solid frames significantly enhances device functionality and has traditionally been achieved at millimeter scales. The ability to encapsulate milli-and microliters of liquid promises to advance material storage, delivery, and chemical reactions. However, conventional methods for liquid encapsulation involve complex, multi-step processes such as patterning, etching, filling, and sealing, which become progressively more challenging as device sizes decrease. This study introduces a novel, single-step method for microscale liquid encapsulation using a localized electrodeposition in liquid (LEL) process. This technique successfully encapsulates picoliters of liquid within micron-sized hollow copper structures. The presence of the encapsulated liquid was confirmed through cryogenic temperature cross-sectional analyses (-180 °C) and by observing structural changes in the microvessels at high temperatures (200 °C). We assessed the mechanical impact of the encapsulated liquid on the copper microvessels' compressive properties, demonstrating the incompressibility of the liquid at room temperature (25 °C) and the load-bearing capacity of ice at cryogenic temperature of-160 °C. Furthermore, we explored the tensile properties of copper-ice composite at cryogenic temperature through compression tests on push-to-pull structures. The LEL process produced well-defined cavity shapes and dense microstructures, enabling precise evaluations of the effects of liquid and its transition to the ice phase at the microscale. Our findings pave the way for enhanced microscale encapsulation applications in microelectronics, pharmaceuticals, and energy storage, highlighting the potential of the LEL technique for advanced device functionality.

Keywords: Additive micromanufacturing, Metal microcylinders, Liquid encapsulation, Micromechanics, High strain rates