Switches disinfect themselves

In this article, Schurter introduces switches with antimicrobial coatings which inhibit or kill microorganisms, ideal for medical, sanitation and food applications


Antimicrobial substances inhibit the growth of microorganisms or even kill them. This approach is not new and consequently various solutions coexist on the market. All disinfectants, for example, are classified as antimicrobial. However, there are also surface structures that have an antimicrobial effect through the disinfecting action of silver and copper or by means of titanium dioxide nanostructures.


A large number of infectious diseases are transmitted via contaminated surfaces. This is called smear infection. Antimicrobial coatings, varnishes and paints can be applied to surfaces, ideal for facilities where high standards of hygiene are required. Examples include hospitals, food facilities, schools, kindergartens and retirement homes. Depending on the particular pathogen, microorganisms can remain active for up to 16-months on surfaces such as door handles, computer keyboards and pay stations.


In cooperation with a German manufacture of paints and varnishes for specialised applications, Schurter put a coating to the test. The effect of coating—which works via the photodynamic principle—was tested on switches.


Photodynamics is based on the excitation of a photocatalyst by light waves in the visible spectral range (400 to 700nm). Energy transfer to the ambient oxygen produces singlet oxygen (¹O₂). This reactive oxygen species kills microorganisms by oxidation.


The results were convincing. All sealed switches (piezoelectric, capacitive or ToF) suit the upgrade. Only switches with a circumferential groove (with a mechanical stroke) proved more difficult to coat since the coating could flow into the switch’s interior. For these, the coating can be applied before assembly and limited to the actuator.


Schurter is now offering this upgrade as a customer-specific variant. Switches are a common man/machine interface, making it important to find the ideal switch for a given application.