New sensors to combat the proliferation of bacteria in very high-humidity environments

"Humidity is one of the most controlled and most monitored aspects nowadays owing to its great importance in a whole range of industrial processes or in areas such as food monitoring, air quality, biomedicine or chemistry," explained Aitor Urrutia, who is from Auritz/Burguete, but who currently resides in Irúñea-Pamplona. "Yet problems remain in terms of measuring and monitoring it in specific situations such as environments where the humidity level is very high".

The proliferation of bacteria in such environments where the humidity is very high is common and this leads to the formation of "biofilms" which are ecosystems made up of these microorganisms attached to a surface. This leads to the problem known as biofouling which causes "the deterioration of many materials and devices, affects their performance and cuts their service lifetimes. Right now, the costs arising out of biofouling are very high mainly because of the maintenance work or replacement of equipment," pointed out Urrutia.

When considering this widespread problem, in his PhD thesis Aitor Urrutia set about building new humidity sensors that would have antibacterial properties for applications that function in environments where the humidity is high and which are conducive to bacterial growth, and thus prevent the creation of biofilms and overcome biofouling.

To develop the various humidity sensors, Aitor Urrutia based himself on the combination of the latest advances in nanotechnology (new materials and new manufacturing techniques for coatings and nanoparticles) over new fibre optic configurations. "The sensors developed are made up of an optic structure to which coatings with a thickness of less than one micron are applied," pointed out the new PhD holder. "Thanks to the embedded silver nanoparticles included, these coatings provide the sensors with two additional functionalities: antibacterial properties and increased sensitivity. That way, the new sensors developed have longer service lifetimes and perform better".

What is more, these fibre optic sensors offer additional advantages such as "their biocompatibility, immunity with respect to electromagnetic interference, their low cost, size and weight, and the possibility of long-distance measuring," according to Urrutia, whose PhD thesis was supervised by the lecturers in the Department of Electrical and Electronic Engineering Francisco J. Arregui-San Martín and Javier Goicoechea-Fernández.

The new humidity sensors developed could be integrated into a wide variety of sectors, such as, for example, health centres and hospitals to monitor human respiration, among other applications; on premises and in chambers used in processes in the foodstuff and pharmaceutical industry; in biotechnology and home automation; and in the monitoring of structures or cavities that are difficult to access, such as cooling towers or off-shore facilities.

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