Low-cost electrometer for self-sensing construction materials: design and measurement insights for smart concrete and bricks

The implementation of strain-sensing structural materials for structural health monitoring (SHM) in civil engineering has the potential to enable self-diagnosing buildings, including masonry and concrete structures. However, a major bottleneck of such technologies is the high cost of the measurement hardware. Dealing with smart sensing systems that require expensive laboratory equipment is impractical for the construction industry. Researchers typically use costly laboratory power sources, signal generators, and acquisition systems for measuring structural responses using smart self-sensing materials, due to performance and reliability reasons. In particular, promising sensing composites evaluated in this paper are piezoresistive nanocomposite or microcomposite concretes and bricks that allow measuring mechanical strain using their piezoresistive response. To address the issues above for such kind of materials, the newly proposed smart construction materials electrometer (SME) device offers a practical alternative to off-the-shelf hardware. The SME can generate sinusoidal, triangular, and biphasic signals with ±10 V and program signal frequencies ranging from 1 Hz to 10 Hz. What is more, it can also accurately measure the electrical outputs of smart materials under an applied mechanical load or change in environmental conditions. The SME provides significant advantages over traditional instrumentation: it integrates multiple functionalities for state-of-the-art measurements in self-sensing materials such as smart concretes and smart bricks, allows easy mobility for field testing, is about 50 times cheaper than commercial devices, and offers versatile and accurate measurements. These benefits are confirmed through experimental tests on commercial resistors, comparisons with off-the-shelf high-cost equipment, and field measurements on real structures. The proposed SME is a crucial step toward the practical implementation of strain-sensing structural materials and their widespread use in real-world SHM applications.