Mechanically driven bacteria-based crack detection

Abstract

Early detection of fatigue cracking is critical for extending the lifetime of structural materials and reducing waste from premature part replacement or over-engineering. Current detection methods, such as strain sensors and ultrasonic testing, are costly, maintenance-intensive, and lack any built-in response to damage. Here, we present a durable engineered living coating that enables in situ crack detection of conventional structural materials. The coating integrates bacterial spores within a tailored synthetic polymer matrix, combining the mechanochemical control of the matrix with the biological responsiveness of the spores. Upon crack formation, the coating produces a fluorescence signal that directly reports damage under diverse loading conditions, geometries, and material systems. This biohybrid platform establishes a scalable and generalizable strategy for sustainable material design. Beyond detection, the modular spore-polymer architecture offers potential for next-generation multifunctional coatings capable of not only sensing but also mitigating crack propagation. This work demonstrates a new approach for integrating living components onto structural materials to enhance their durability, safety, and sustainability.