Screens are in, buttons are on the way out. Touching said screens inevitably leaves fingerprints at best, germs at worst, leaving the screen looking bad and potentially dangerous—especially in shared vehicles. Science to the rescue! We've covered various schemes to sanitize vehicle interiors by flooding them with ozone or ultraviolet light, but on Valentine's Day, GM was awarded Patent No. US 11,579,340 B2, for a self-cleaning touchscreen that's also self-disinfecting.
This system does not rely on the germicidal 254-264-nm UV-C wavelength used to disinfect water supplies, hospitals, airplane interiors, etc. (which Michigan-based supplier GHSP's Grēnlite vehicle-sterilizing system proposes using). Instead, ultraviolet illumination from LEDs (typically 365-405nm) activates a photocatalytic coating applied to the touchscreen. That material is normally water repellant, but when activated by UV light (sufficient sunlight can trigger it), it becomes hydrophilic, meaning it absorbs moisture from the air. With the moisture, the catalyst effectively kills and removes any organic material on the surface. A similar technique is currently used to self-clean solar panel surfaces. Touchscren
A study of the patent indicates that the coating starts with a metal oxide, like the metastable mineral form of titanium oxide (TiO2) called anatase. The key is that it must have a band gap in the UV or near-UV portion of the light spectrum. This coating is then doped with another material, which can be a transition metal from the D-block (the low center part) of the periodic table, or even by a non-metal like nitrogen or fluorine. This doping shifts the band gap so that the photocatalyst is activated not only by sunlight but also by the LED-sourced UV light.
The patent illustration indicates the UV LED emitters snuggled right in between red and green emitters directly above and below them, flanked by blue emitters to either side. The UV light is invisible to the human eye, so we shouldn't notice when they're illuminated. It's unclear, however, whether not having a visible-light emitter in those regions will affect screen resolution, brightness, etc. (Probably not).
Touchscre The patent protects for various automatic or timed cleaning cycles, and for zoned cleaning of areas featuring frequently used button areas that need more attention. It also covers all touchscreen types (mobile, public-use screens, etc. ).