WILD Rethinking desinfection Light kills bacteria, germs and viruses. And it is extremely good at it. Photonic demonstrates why the coronavirus pandemic may change approaches to disinfection.

When the outbreak of the new SARS-CoV-2 in China became known in mid-January, the rest of the world did not foresee the far-reaching impact that the coronavirus crisis would have. One of the reasons for the rapid spread of Covid-19 is its ability to survive longer on surfaces and objects than other types of virus. Therefore, authorities worldwide are now trying to contain the spread of the virus by means of disinfection. Regular hand washing and hand disinfection also contribute to stopping contagion.


Disinfection using UV light

The most commonly used means of eliminating viruses on surfaces are disinfectants. Areas of public life such as, for instance, public transport, food stores or toilets cannot be permanently cleaned using disinfectants. A simple, efficient alternative is disinfection using UV light. This method has been used successfully for several years in food production, drinking water treatment and sterilisation of ventilation systems. The Chinese metropolis of Shanghai even went a step further, using this technology in a wash tunnel to disinfect commuter buses. An even more innovative solution are the autonomous mobile robots that are now killing viruses and bacteria in several Chinese hospitals using ultraviolet light. It is easy to explain why this technology has suddenly been met with such enormous interest: it is quick, cost-effective and reliably eliminates germs, bacteria and viruses.

“In order to disinfect surfaces efficiently using UV light, you must evenly radiate the object with a sufficient dose. Thanks to its know-how in the area of light technology, Photonic is ideally positioned to quickly and efficiently implement such application-specific solutions”, explains Photonic Development Manager Stefan Zotter. “Our experts recently designed a UV curing chamber in which 3D-printed objects of any shape can be homogeneously irradiated from all sides using UV LEDs. This requires careful consideration of parameters ranging from the choice and positioning of UV LEDs to the surface material of the chamber, the control of the individual LEDs and the thermal management of the entire system”. Photonic supports its customers in all product development stages: from the first concepts to serial production, the light experts will contribute their year-long experience in optics, mechanics, electronics and software to the project, thus boosting the success of the customer’s products.


Areas of application of photodynamic disinfection

In many areas, however, disinfection using UV light does reach its limits. UV radiation, and especially the short wave UV-C light predominantly used in surface disinfection, is extremely dangerous to humans without adequate protection. The hazardous radiation can cause severe eye injuries and may lead to cell mutation and cancer when absorbed by the skin. This is the reason why alcoholic solutions are still being used for hand disinfection, which may result in skin irritation when used frequently. Moreover, numerous studies show that most people do not disinfect their hands adequately.

In contrast, photodynamic disinfection uses a harmless liquid called photosensitizer in combination with non-hazardous, visible light. The light-activated substance is applied to the object and reacts with light and air to create reactive oxygen, which very effectively kills germs, viruses and bacteria. This method is very successfully used in the treatment of badly healing wounds and in dental medicine or dermatology. Stefan Zotter believes that “in the future, the combination of hand washing and rigorous rubbing with disinfectants still necessary today may be replaced by photodynamic disinfection”. “This would involve applying the photosensitizer by evenly rubbing it into the hands and then exposing them to light to eliminate undesirable germs, bacteria and viruses”. The greatest challenge, however, is convincing the people that a device is also required in addition to the disinfectant. The device is a system incorporating a lot of experience and know-how in the field of optomechatronics. This is not the only factor that favours Photonic. “Customers who want to implement innovative disinfection products will benefit from a cooperation with us already when defining the product requirements. When determining the requirements for a specific device, we can resort to a wide range of knowledge stemming from our daily involvement with normative and regulatory safety requirements relating to light generation and control. Therefore, our customers can be sure that the envisaged properties of their system will pass the reality check of product authorisation and feasibility”, Photonic Business Developer Joachim Enengl explains.

The world we live in will be a different one after the Covid-19 crisis. The possibility of contracting a disease through a simple handshake or by touching a door handle will be engraved in people’s minds. The need for a quick and efficient elimination of germs, viruses and bacteria is bound to grow. Whether through radiation using UV light or the use of photodynamic disinfection, Photonic offers its customers ideal expertise in the area of light technology, allowing them to develop bespoke systems and manufacture these with high precision and accuracy.