Design for an ultrafast water distributed sensor employing polyvinylamine cross-linked with Cu(II)

In this work, we developed a new sensor based on a specially designed polymer–metal complex which has the following characteristics: (i) resistance to dissolution in water, (ii) mechanical toughness, (iii) rapid reaction to humidity changes and (iv) precise pinpointing of a water leakage through simple technology. A hydrogel of polyvinylamine cross-linking with Cu(II) salts is employed as sensing material which has an ultrafast electrical response when it is exposed to water. Employing this composite it is possible to extrude in length continuous cables, which permits the production of actual distributed sensors of several kilometers long, which may survey water leakages or filtrations in a number of civil constructions as; pipelines, buildings, electric power stations, libraries, etc. Three PVAm formulations with different contents of Cu(II) salts were prepared and evaluated. Their cross-linking density was evaluated by viscosimetry and swelling tests, and its effect over morphological, thermal, rheological and electrical properties was evaluated by: SEM, TGA, rotatory rheometry and four probe resistivity measurements. A distributed water sensor prototype was prepared with PVAm–Cu(II) and its capability to detect and pinpoint water leakages was assessed. Experimental results showed that this sensor has an excellent performance on monitoring long water pipelines.