In-situ graft fibrous PPy@PEI enables sensitive and all-seasoned crack monitoring for ancient architectures based on flexible pressure sensors

The non-destructive, real-time, and automatic monitoring for the development of cracks in ancient architectures is crucial to the preservation of precious ancient heritages. Here, light-weight crack sensing constructed with ultra-thin and high-performance flexible pressure sensors is proposed to fulfill this demand. The signal drift and poor reversibility commonly observed in widely-reported sensors based on elastomer matrix, which originates from the creep and relaxation behaviors, are addressed using piezoresistive polypyrrole-grafted polyetherimide fibers. The corresponding flexible piezoresistive sensors exhibit great sensitivity (9.45 kPa−1 in 0 ∼ 1 kPa and 3.48 kPa−1 in 3 ∼ 10 kPa), outstanding static stability (5.13 % signal drift after 48 h under 1 kPa), dynamic durability (4.72 % degradation after ∼30,000 cycles) and excellent robustness across an ultra-wide temperature range of −70 ∼ 150 ℃. Based on this highly reliable pressure sensor, the proposed non-destructive crack sensors integrated into an Internet of Things (IoT) platform display outstanding stability during their service in the Forbidden City. By virtue of the low energy consumption, one lithium battery can power the monitoring system for more than one year.