Mechanically Driven Bacteria‐Based Crack Detection

Early detection of fatigue cracking is crucial to extend the life‐cycle of materials and structures. To reduce the risk of fatigue, parts are often over‐engineered or retired early, leading to material waste. Current methods for crack detection, including strain sensors or ultrasonic testing, can be costly, require regular maintenance, and do not respond to cracks directly via a repair mechanism. People are leveraging biology to create materials that can sense and respond. Engineered living materials have been primarily limited to porous matrices and hydrogels, which facilitate viability of organisms. We present an engineered living coating that can be applied to conventional structural materials to detect cracks. The coating integrates bacterial spores into a tailored synthetic matrix. This biohybrid coating approach unlocks potential, beyond crack detection, for crack mitigation through leveraging the biological component. This study: 1) describes the design of a spore‐polymer coating for in situ crack detection for structural materials and 2) demonstrates detection for different loading mechanisms, geometries, and materials. This work demonstrates how living materials can be used to enhance conventional materials and creates a valuable approach for crack detection. Our coating will reduce waste, increase product lifespan, and improve safety by preventing failure due to cracks.