Fabrication of Solid-Liquid Composite Micro-Architecture and Their Deformation Behavior

Architected materials, composed of solid materials with pore channels, exhibit unique deformation behavior and mechanical properties. By altering the composition of the solid material or introducing different materials, the properties of architected materials can be further tuned. However, the introduction of liquid materials to architected materials has not been investigated due to intrinsic fabrication constraints in the widely used additive manufacturing processes. In this study, we demonstrate the feasibility of solid-liquid composite micro-architectures using a recent additive micromanufacturing technique based on localized electrodeposition.<br/>As a case study, we designed and fabricated simple pure copper (Cu) micro-vessels containing pico-liters of liquid. The existence of the liquid was confirmed through cross-sectional analysis using cryogenic-focused ion beam microscopy. Atom probe tomography was employed to measure the chemical composition of the pure copper and the encapsulated liquid. Nano computed tomography (NanoCT) results confirm the dense pure copper vessel walls with the liquid confined inside the vessel. Importantly, we investigated the effect of the liquid on the deformation behavior and mechanical properties of the micro-vessels using a <i>in situ</i> micromechanical testing system capable of metrology at high speeds and sub-ambient temperature conditions. The micro-vessels exhibited significantly different stress levels and strain rate dependencies depending on the phase (water to ice transformation under cryogenic conditions).<br/>In addition to the microstructural and mechanical characterizations, we will discuss the feasibility and potential of solid-liquid composite architectures at the microscale as novel structural and functional materials.