UV technologies for sterilization and disinfection of surfaces

Challenges

Surfaces contaminated with microbial pathogens must be disinfected in many areas. For a longer shelf life of food, the packaging must be free of contaminating germs. In the pharmaceutical sector, various materials such as packaging, but also filling units, must be kept germ-free. In medical technology, surfaces that could otherwise lead to infections in hospitals must be sterilized. For these surfaces, additional safety is required.

Solution

Among other technologies, UV technology is developed and used at Fraunhofer IGB to inactivate viruses, bacteria and spores on a wide range of surfaces in the food, pharmaceutical and medical technology sectors.

UV technologies have the advantage of being dry and free of harmful gases and their degradation products. There is also no temperature stress.

The use of mercury vapor lamps is quite common. These lamps can be used for many purposes with their spectrum mainly in the range of 254 nm. But UV is not all the same: organisms often have different "sensitivity windows" in which they react differently to radiation. This is based on photochemical processes which can damage, for example, RNA or DNA, but also the membrane of bacteria or the viral envelope. The viral envelope not only protects the RNA but also enables it to penetrate host cells in the first place.


Selection of the wavelengths that specifically inactivate the organisms

Living organisms such as bacteria, algae and fungi can (to a limited extent) counteract UV radiation by active repair measures. Bacterial and fungal spores as well as viruses have practically no active repair mechanisms, but they can protect themselves to a certain extent by UV-blocking substances or radical scavengers.

But if the UV wavelength is specifically selected, weak points of the contamination can be specifically "addressed" – for example, by irradiating with high intensity at a wavelength at which no UV-blocking effect is present or by causing damage for which repair mechanisms are not effective. Sometimes, there are some orders of magnitude between the inativation results achieved with unsuitable and appropriate UV irradiation.

 

Removal of pyrogens

We also use UV lamps to remove residues of killed microorganisms from surfaces. These are the so-called pyrogens: they are dangerous because they can trigger life-threatening sepsis – even though they "only" consist of dead membrane residues.

UV radiation from specially developed excimer plasma lamps can inactivate bacteria and even spores.
© Fraunhofer IGB
UV radiation from specially developed excimer plasma lamps can inactivate bacteria and even spores.

Selection of suitable gas discharge lamps

The choice of the appropriate UV technology does not only depend on the wavelength.

We therefore use different gas discharge lamps, including specially developed excimer lamps, which are characterized by high efficiency. These are available with different emission wavelengths and are mercury-free, which is particularly important in the food sector (see OVOSHINE project below). Excimer technology even allows irradiation in the vacuum UV range, a wavelength range in which even water molecules can be broken up (EP3134350 (B1)).

UV-LEDs are another technology. These are characterized by a particularly long service life, are frequently switchable and can be configured very flexibly to irradiate even complex geometries.

 

Spectrum of services

With its UV irradiation systems, Fraunhofer IGB has developed a technically simple and inexpensive alternative to other disinfection or sterilization methods that is suitable for a wide range of applications.

In addition, the lamps can also be used for surface activation prior to gluing, painting or printing.

We can advise you on the selection of the radiation source for your specific application and support you in the implementation.

 

Development of processes for the inactivation of viruses, bacteria and spores on a variety of surfaces in the food, pharmaceutical and medical technology sectors using UV technologies

  • Selection of suited UV sources
    • Gas discharge lamps, excimer lamps, UV-LEDs
  • Adaptation of the wavelengths to the organisms to be inactivated
  • Adaptation of the process for removing pyrogens
  • Design, building and implementation of the UV sources

 

Evaluation of sterilization efficiency

Expertise and laboratories up to safety level S2 are available to evaluate the sterilization efficiency on customer material contaminated with different organisms.

Reference projects

 

Ovoshine – Safe foodstuffs through physical disinfection

In the EU project Ovoshine, we were able to show that UV radiation from specially developed excimer plasma lamps and UV LEDs can act effectively against bacteria and even spores, thus inactivating dangerous Salmonella pathogens on egg shells.