Two in One: Jet Personal Air Shower and Photodynamic Disinfection in One Device

Fig. 1: PDS Lock

Fig. 2: Details of PDS lock

Fig. 3: Jet Air Shower

Josef Ortner, CEO Ortner Group

The PDS Function

To activate the photodynamic function, two elements are required: light and color. The color is provided by the clothing. The PDS lock ensures the correct wavelength and light intensity.

The intensity of the light is a crucial factor for activating the substance. Only at a very specific wavelength and light intensity is the light energy transferred to the oxygen, which can then perform its actual function.

"The special know-how for activating the dye actually lies in the lighting technology. It is especially important that the light is evenly distributed across all positions," explains Josef Ortner.

The PDS lock is equipped with a daylight-compliant light wave and is thus accessible even without protective glasses. The duration of the disinfection phase depends on customer requirements, ranging between 2:30 and 3:00 minutes. "The posture and position of the person are critical factors in ensuring comprehensive decontamination. That is why the integrated sensor system is important. Correct foot placement and hand positioning are monitored via sensors." To make the disinfection process more engaging, the lock also features an integrated entertainment system. (see Fig. 1 + 2)

Jet Air Shower

Removing particles is already quite a delicate matter. Removing particles from clothing is a whole different challenge. With the new Jet Air Shower, efficient particle removal has been demonstrably achieved. Physical laws have been calculated in detail and are applied in the new Ortner Jet Air Shower.

- The jet nozzle technology is responsible for loosening or shearing particles on clothing. To prevent excessive mixing of air in the lock and thus possible recontamination of the persons, an effective timing control of nozzles and displacement airflow has been developed.
- The jet stream generates rapid vibrations on the textile surface, supporting the cleaning effect in the lock.
- To ensure the optimal impact angle of the air from the nozzle, the person's position is monitored. This is especially important for arm and leg areas. Using 3D reconstructions, the ideal position of the person was determined and the nozzles aligned accordingly.
- Utilizing wall shear stress: The jet is adjusted to be safely guided over the body to be cleaned, reaching every body part.
- The perfect displacement airflow is crucial to ensure cleaning success in an air shower. The displacement airflow is realized through a vertical "laminar flow"-like supply air stream.

With these measures, it is demonstrably possible to ensure a genuine cleaning effect in a personal air shower. Thanks to the integrated laminar flow unit, the lock can also be used at any time as a material lock.

This is the first step toward achieving purity in a room. Whenever microbiological cleanliness is required, the PDS lock can be expanded with a photodynamic unit. (see Fig. 3)

What is Photodynamics?

In photodynamics, positively charged photosensitizers (dyes) are used to generate an antimicrobial effect. These attach to the negatively charged cell wall of microorganisms.

When the photosensitizers are subsequently irradiated with visible light, they absorb the light energy and transfer it to the oxygen nearby. The activated oxygen (singlet oxygen) is produced directly at the microorganisms and destroys them via oxidative pathways.

Cleaning Efficiency of Air Showers

Assoc. Prof. Dipl.-Ing. Dr. techn Stefan Radl is at TU Graz at the Institute for Process and Particle Engineering. The particle-efficient design of cleanroom equipment is one of his specialties.

His insights on air showers

The analysis of particle adhesion shows that the removal force on particles is linearly proportional (parallel to the surface) or quadratically proportional (perpendicular to the surface) to the wall shear stress. Furthermore, the vibration of cleanroom clothing can play an important role, especially for larger particles. However, the adhesion forces of particles on surfaces are the real problem: these depend heavily on environmental conditions (e.g., humidity) and particle properties (size, shape, surface roughness). The analysis of the technical design of air showers revealed an important trend: the use of pulsed air jets.