Effective disinfection using Liteon UV-C LEDs

The distance between the UV LED and the item to be disinfected is determined by the compromise between the viewing angle and the chamber's external dimensions. Let us assume that the smartphone placed in the chamber is not larger than 160×80×12 mm. See Figure 1. for the sketch drawing. Chamber construction design can be made using graphic objects – simply sketch the UV LED, the irradiated object and arrange these components as needed. The chamber and the object are not large, so we recommend using the 1:1 scale. Once it is ready, simply dimension the drawing with the use of software or a ruler.
 

What can we learn from the sketch? UV diodes should be installed as close to one another as possible. At the same time, we need to remember that LEDs have a relatively high power and as a result they can heat up during service, so the distance between LEDs and the object needs to be a compromise. Due to that, four UV LEDs have been used in our chamber, two at the top and two at the bottom. If the distance between the LEDs is about 80 mm, the shortest distance between them and the object (to ensure that the UV beam can cover the entire smartphone) will be 25 mm. Calculating the shortest distance is important here, as it can have an effect on the dimensions of the chamber, which we want to keep as ergonomic and compact as possible. Moreover, we must note that the power of the LEDs is relatively high, so it is important to provide the cooling airflow. If required, a fan can be used to force it.

Now, we will include the dimensions from Figure 1 in our design plans. In order for the object to fit into the chamber and for its edges to be irradiated, there needs to be a certain space between the chamber casing and the object. Let us assume it is 4 mm. With the smartphone dimensions of 160×80×12 mm, and the distance from the object to the UV diode being 25 mm, the internal dimensions of the chamber will be 168×88×62 mm.

See Figure 2 for an example of the chamber design. We need to make sure there is  space for the safety switch (which will switch off the UV light whenever the lid gets opened), mounting holes for UV LED plates, holes for wires and connectors, mounting space for the electronic board with buttons, the window for the display or other indicator of the set switching time, lid hinges, etc. The design of the smartphone disinfection chamber presented here might be implemented e.g. using a 3D printer. There are four brackets which support the smartphone in the lower part of the chamber. Depending on the item to be disinfected, these can be designed to look and be placed differently.