The applications of the paper will benefit businesses and municipal authorities. A water leak, especially in a large building or in a town, inevitably causes havoc. Such leaks are also very difficult to trace. Often engineers are required to disassemble great lengths of pipework. Moreover, these types of water leaks come at great economic cost.
To aid with the detection of water leaks, University of Washington researchers have developed a so-termed “smart” paper, where the paper can detect water. This is possible through lacing the paper with conductive nanomaterials (formed from extremely conductive carbon). These can be deployed as a switch whereby an LED light or an alarm system can be activated when water is present.
Discussing the technology, lead researcher Professor Anthony Dichiara told Controlled Environments magazine: “Water sensing is very challenging to do due to the polar nature of water, and what is used now is very expensive and not practical to implement. That led to the reason to pursue this work.”
In terms of how this might work in practice, this is set out in the following video:
The major complexity with the development was embedding nanomaterials into the paper so that electricity could be conducted. This process began with pulp. The development required the manipulation of wood fibers and carefully mixing of the nanomaterials. This took several iterations.
The research then shows that when water droplets fall onto the paper, an LED light functioned indicating that the conductivity had been turned off. By further developing the process the paper created is fully reversible in that once the paper has dried, the conductive network re-forms. This means that the paper can be re-used multiple times.
For the commercial model, the paper will be fitted with a battery and the sheet wrapped around a pipe or under a series of intersecting pipes. Then, if a pipe was to leak water, the paper would detect the water and this would trigger an electrical signal wirelessly to a central control center. This would enable an engineer to identify the source of the leak.
The lightweight, flexible, and electrically conductive paper can be produced at a low cost and relatively rapidly. In terms of production, existing paper manufacturing methods can be easily modified.
It is also hoped that the paper can developed further, utilizing the water detection properties so that water can be sensed in the presence of other liquids. This could be useful, for example, in the chemical industry to screen for impurities. Contamination testing, detection, identification and analysis are crucial steps towards resolving suspected contamination of products and processes, and this type of method will be useful to many industies.
The research has been reported to the Journal of Materials Chemistry A. The research paper is titled “Smart papers comprising carbon nanotubes and cellulose microfibers for multifunctional sensing applications.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week, we profiled scientists who have designed an electronic artificial skin which has the capability to ‘glow’ when the surface is damaged. The application will have several medical uses.
The week before we looked at a “molecular pencil sharpener.” This is a device that uses chemicals to generate a “warhead” of proteins that increase in toxicity once “sharpened”. The research has focused on killing the Escherichia coli bacterium.
