University of Washington (UW) researchers have developed an electric smart paper that helps detect leakages assailing water pipelines.
Nearly a quarter-million water line breaks occur each year in the U.S., costing public water utilities about $2.8 billion annually, reports the American Water Works Association.
Hoping to remedy this, UW undergraduate students led by UW assistant professor Anthony Dichiara have laced the paper with conductive nanomaterials, which can be employed as a switch, turning on or off an LED light or an alarm system indicating the absence or presence of water.
Starting with pulp, the researchers manipulated the wood fibers by carefully mixing them in nanomaterials using a standard process for papermaking, but never before used to make sensing papers.
When water hits the paper, its fibrous cells swell to up to three times their original size. That expansion displaces conductive nanomaterials inside the paper, which in turn disrupts the electrical connections and causes the LED indicator light to turn off.
According to the researchers, this process is fully reversible, and as the paper dries, the conductive network re-forms so the paper can be used multiple times.
Moreover it is so sensitive that it can also detect trace amounts of water in mixtures of various liquids. This ability to distinguish water from other molecules is particularly valuable for the petroleum and biofuel industries, where water is regarded as an impurity.
The nanomaterials added to the paper were engineered in such a way that they can be incorporated during conventional papermaking without having to modify the process. These materials are made of extremely conductive carbon.
The UW team has also experimented with making nanomaterials from banana peels, tree bark and even animal feces. They have even tried making nanomaterials from wood scraps to show that the entire papermaking process can be completed with cheap, natural materials.
Image, video and content: Mark Stone/University of Washington