Process and property assessment of liquid metal spray deposition towards scalable and reliable stretchable electronics

Abstract

Liquid metal stretchable electronics combine exceptional softness, stretchability, and self-healing capabilities, making them ideal for smart wearables and soft robotics. A key fabrication approach involves pneumatic spray deposition into patterned structures. However, the impact of process parameters on LM deposition remains poorly understood, largely due to reliance on manual airbrushing-limiting both scalability and reliability. This work addresses these challenges with a custom-built automated spray coater, offering precise control over key parameters such as flow rate, pressure, and spray distance. Through systematic process–property analysis, we reveal that rougher coatings improve device yield (approaching 100%) but compromise long-term reliability. Finer linewidths (0.25 mm) fail earlier in cyclic testing and exhibit reduced self-healing compared to wider lines ( 0.5 mm). Scalability is demonstrated through the fabrication of a large-area wearable strain sensor (70 150 mm) for human motion capture. These findings offer critical insights into process–structure–property relationships, paving the way for reliable, scalable LM-based stretchable electronics.