Arbitrary-shape-adaptable strain sensor array with optimized circuit layout via direct-ink-writing: Scalable design and hierarchical printing

The online strain acquisition is highly desired for structural monitoring of key equipment such as aircrafts or high-speed trains. However, there are still enormous challenges to monitor full-field strain in large area with arbitrary shape, especially when the non-contact approaches are not applicable. In this study, we firstly develop an optimization design principle for arbitrary-shape-adaptable sensor array with scalable circuit layout, and then a hierarchical printing strategy by direct-ink-writing is proposed to enable simultaneous monitoring in large-scale area or multiple domains. According to the design principle and printing strategy, the proof-of-concept sensor arrays (e.g. with 8 × 8 and 4 × 16 grids) are designed and printed by bottom-up hierarchies from the layered components (e.g. wires, filaments and isolation intervals) to the main arrays through distributed printing sub-arrays (4 × 4 grids). In particular, the strain field surrounding a hole is monitored in high-precision based on the present strain sensor. This work also provides insights of sensor array from adaptive design to high-efficient DIW-fabrication for other applications including wearable electronics, small-batch equipment and individual medical devices.