Public touchscreens, such as those used in ATMs or ticket payment systems, which are accessed by different people in a short period of time, could transmit pathogens and thus spread infections. Therefore, the aim of this study was to develop and test a prototype of a touchscreen system for the public sector that disinfects itself quickly and automatically between two users without harming any humans.
A quartz pane was installed in front of a commercial 19” monitor, into which 120 UVC LEDs emitted laterally. The quartz plate acted as a light guide and irradiated microorganisms on its surface, but—due to total reflection—not the user in front of the screen. A near-infrared touch frame was installed to recognize touch. The antibacterial effect was tested through intentional staphylococci contamination.
The prototype, composed of a Raspberry Pi microcomputer with a display, a touchscreen, and a touch frame was developed, as well as a simple game programmed that briefly switched on the UVC LEDs between two users. The antimicrobial effect was so strong that 1% of the maximum UVC LED current was sufficient for a 99.9% staphylococci reduction within 25 s. At 17.5% of the maximum current, no bacteria were observed after 5 s. The residual UVC irradiance at a distance of 100 mm in front of the screen was only 0.18 and 2.8 µW/cm2 for both currents, respectively. This would allow users to stay in front of the system for 287 or 18 minutes, even if the LEDs would emit UVC continuously, and not be turned off after a few seconds as in the presented device.
Therefore, fast, automatic touchscreen disinfection with UVC LEDs is already possible today and with higher currents, disinfection durations below 1 s seems to be feasible, while the light guide approach virtually prevents the direct irradiation of the human user.
