What does hand disinfection with light mean?
In a light-based approach, UV radiation is directed at a defined area. Our development goal is to treat both hands inside a station without dispensing liquid disinfectant onto the skin. This changes the engineering requirements: the areas reached, intended hand positions and conditions of the proposed cycle must be established. A visible status indicator alone does not describe these optical properties.
Why consider 222 nm far-UVC?
Far-UVC is ultraviolet radiation in the shorter-wavelength part of the UV-C range. As a component example, Ushio describes a krypton-chloride excimer module emitting around 222 nm with optical filtering. Filtering limits unwanted spectral components. Such a light source is a possible technical building block; it is not a complete hand sanitizer. Selection of this particular module for Trimed is not committed.
Distinguish wavelength, irradiance and dose
Wavelength is expressed in nanometres and describes the spectral position. Irradiance describes the radiant power arriving per unit area, for example in µW/cm². Radiant exposure, often called dose, is accumulated over time, for example in µJ/cm² or mJ/cm². For constant irradiance: dose = irradiance × time. This relationship alone does not establish an effective or permissible treatment duration.
Why is a lamp diagram insufficient?
A diagram may describe irradiance at the centre of a light cone. Hands are not a flat measurement plane: fingers, spaces between fingers, backs of hands and changing positions create different conditions. Distance, shadowing and reflections therefore belong in device engineering. Measurements from a room luminaire at a distance of one metre are not released hand-station specifications. Studies on airborne microorganisms or agar plates likewise do not establish particular performance on hands.
What evidence is planned for Tech 222?
- Investigate efficacy on the complete device under defined conditions.
- Assess dose distribution and intended hand positions.
- Assess skin and eye exposure and relevant failure cases.
- Define instructions, intended users and conditions of use.
The new Trimed station is in development. A binding treatment duration, validated disinfection performance and suitability to replace existing hygiene procedures are not committed. A project enquiry should therefore identify the intended application and the evidence required.