Smartphones, tablets and similar mobile companions are picked up countless times a day. However, hygiene aspects usually play a subordinate role. In the clinical sector, however, things are different. Here, tablets and smartphones are now used in a variety of ways and are also passed from hand to hand. Disinfection is therefore essential to prevent the transmission of pathogens.

However, the use of chemical agents is out of the question here, as this would destroy the grease-repellent coating of the displays. Researchers at the Fraunhofer IOSB-AST in Ilmenau have developed a technical innovation for this purpose: from the outside, it looks like a standard microwave. On the inside, however, so-called UVC LEDs - light-emitting diodes that work with ultraviolet light - with a wavelength of 269 nanometers are used.

A total of two separate UVC LED modules, each with ten UVC LEDs, are installed for the top and bottom of the smartphone. Each UVC LED has an output of 100 milliwatts, meaning that the total radiation output is two watts. This achieves an irradiation dose of 800 J/m² in just a few seconds, which enables efficient inactivation of bacteria and viruses.

Smartphones are not only disinfected with the solution using light, but are also identified using an NFC reader and the applied dose is recorded and logged using a sensor. This means that every disinfection process can be validated and clearly assigned to the respective device. An LCD display informs the user about the most important functions. Furthermore, downstream IT systems can be integrated via WLAN and web interface.

"For many years, we have been working on very different applications for UVC technologies in the field of disinfection as part of the BMBF's 'Advanced UV for Life' program. LEDs offer great advantages, which we can demonstrate excellently using the example of smartphone disinfection," explains engineer Thomas Westerhoff from Fraunhofer IOSB-AST.

The areas of application for cell phone disinfection range from the clinical sector to private and commercial use and the event market. The prototype is expected to be presented in September 2020 at IFAT, the world's leading trade fair for water, sewage, waste and raw materials management in Munich.

Fraunhofer IOSB-AST is still looking for partners from industry for commercial exploitation. as