High-Resolution Liquid Alloy Patterning for Small Stretchable Strain Sensor Arrays

Soft material applied technology has in recent years become more advanced, enabling for, e.g., soft robotics, skin electronics, and wearable systems. Yet, the processing technology of soft materials has not been sufficiently developed to create high performance in soft and stretchable systems, as compared to the processing technology of conventional electronics or electromechanical systems. Liquid alloys have shown excellent properties for soft and stretchable electrical interconnectors and conductors, which is a basic building block to produce electric or electromechanical systems. In order to overcome the limited resolution of previously developed liquid alloy patterning methods for large-area printed circuits, this work explores the possibility of employing shrinking substrates. By utilizing the characteristics of liquid alloys and elastomers the pattern resolution is improved through a stretch-shrink patterning (SSP) process. The process provides highly conductive liquid conductors of high resolution and can be combined with existing printing techniques for liquid alloys. The SSP process increases design flexibility of soft and stretchable systems that use liquid alloys and enables designs with finer and denser patterns, and cost-effective production for small scale systems.