Rethinking Disinfection in the age of Covid-19

By Dr Vinayak Ghate, Research Fellow, National University of Singapore

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COVID-19 has made an unprecedented impact on businesses. This impact has been felt not only across borders but perhaps more disturbingly, across market segments. Businesses that did not typically perceive themselves to be hygiene-sensitive, such as public transport, have had to prioritise hygiene. And even those that did, like healthcare and F&B, have had to re-evaluate their hygiene strategies. A part of this re-evaluation stems from the fact that the pandemic has brought business to a halt despite them having deployed several measures to keep germ counts low.

It is well-known that infections can spread through contaminated surfaces. ‘High touch’ surfaces — surfaces that come into contact with human hands more frequently — typically pose the highest risk for indirect transmission. Different environments can have different ‘high touch’ surfaces. For example, within a shopping mall, ATM keypads, escalator handrails and shopping trolley handles are all ‘high touch surfaces’. Likewise, in a typical office, keyboards, elevator buttons and telephones can get contaminated easily.

Currently, the typical way that these surfaces are disinfected is via manual cleaning with chemicals, ultraviolet (UV) light and hydrogen peroxide vapours (in a hospital setting) or ozone vapours (in the food industry). However, these disinfection methods tend to be unsafe to be used around human presence or impractical to be continuously applied. Hence, they end up being ‘episodic’ in nature. Unfortunately, high touch surfaces become re-contaminated very easily — almost immediately after an episodic cleaning.

Forward-looking businesses have been looking into ways to ramp up their cleaning regimen. One such business is Singapore’s IncuBaker® Cafe & Studio, which is a co-working kitchen and F&B incubator. Operating as a shared space, as well as being within the F&B sector, hygiene and safety have always been their top priority. However, in the midst of the current pandemic, they have been taking an even closer look at the quality of the cleaning products used. They have adopted products with proven efficacy against a wider range of germs, including viruses. They have also stepped up their cleaning routine with more frequent disinfection of high-risk areas — not only worktops and cutting boards, but also the shared utensils, which are now heat-sterilised before they are placed in proper receptacles for the next user. The current pandemic has reinforced IncuBaker’s belief in the prioritisation of hygiene. Moving forward, they are considering implementing continuous disinfection to supplement episodic cleaning.

An emerging category of disinfection technologies is continuous disinfection, which is designed to supplement existing episodic methods to reduce infection risk. Continuous disinfection technologies work slowly and steadily round-the-clock to keep surfaces clean, effectively ensuring that once a surface is sanitised, it stays sanitised. An example of a continuous disinfection method is the use of antimicrobial coatings. Antimicrobial coatings work either by preventing the attachment of germs to the surface or by actively killing them once they attach. When applied on high-risk surfaces such as door handles and conveyor belts, these coatings provide a much-needed layer of security between the episodic cleanings. With advances in material science allowing the incorporation of a greater variety of antimicrobial substances into coating formulations, coatings can be expected to gain popularity. One challenge that they are likely to face though, is ensuring their efficacy over time, as their active compounds can get consumed during the antimicrobial action.

A more recent continuous disinfection method has been the use of visible light. This technology is based on the scientific principle of photodynamic inactivation (PDI), which targets light-sensitive compounds that are naturally present inside germ cells. Once excited by the right kind of light, these compounds trigger a series of toxic reactions inside the cells and eventually cause their death. This enables continuous disinfection because the antimicrobial action can be achieved using light that is perfectly safe for humans.

At the National University of Singapore, work on this technology started several years ago under the guidance of the then Assistant Professor Hyun-Gyun Yuk and Professor Zhou Weibiao of the Food Science & Technology Programme (now Department of Food Science & Technology). A company, SafeLight, was spun off this technology with the aim of reducing germs in hygiene sensitive environments using continuous visible light disinfection. This deep-tech endeavour has been supported by the University, through programmes such as the Lean LaunchPad and the NUS Graduate Research Innovation Programme (NUS GRIP). The company is currently developing PDI-based devices that will help businesses enhance hygiene in their operations. These devices will allow for the continuous disinfection of surfaces within facilities, helping businesses reduce chances of contamination in their own products. Depending on the business, this could lead to benefits such as lower re-hospitalisation rates (healthcare), longer product shelf-life (food processing) and enhanced brand reputation (hospitality).

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Food processing is one sector that stands to benefit from continuous disinfection. The above pictures show how a tomato illuminated with SafeLight (left) can avoid spoilage when contaminated with mould, whereas a tomato that is simply refrigerated (right) cannot.

That said, continuous disinfection processes are still in their infancy and more work needs to be done to verify their value before they can go mainstream. Pilot projects performed in diverse environments will go a long way in this endeavour. In some of these environments such as food processing, the effect of light on the food material is likely to be an important factor influencing technology adoption. Which continuous disinfection technologies find a place in tomorrow’s world remains to be seen. But one thing seems certain. Given how COVID-19 has highlighted the limitations of episodic methods, it is a matter of when, not if, continuous disinfection will be the new standard.

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Dr. Vinayak Ghate is a Research Fellow at the National University of Singapore, specialising in visible light disinfection. He has worked on this technology’s development for almost a decade and has published several original research articles in international peer-reviewed journals. He is also an author of three patents on visible light disinfection technology.

Lean LaunchPad Singapore is a 10-week national programme aimed at developing technopreneurial talent to drive innovation and enterprise. It is a platform to learn how to transform academic research into usable, commercial prototypes or products. Modelled after the US I-Corps programme framework, Lean LaunchPad Singapore has nodes at four major universities in Singapore — the National University of Singapore (NUS), Nanyang Technological University (NTU), Singapore University of Technology and Design (SUTD) and Singapore Management University (SMU).

For more information, visit https://leanlaunchpad.nus.edu.sg/.

Launched in 2018, the National University of Singapore Graduate Research Innovation Programme (NUS GRIP) is the Industry Liaison Office’s flagship innovation programme. It provides step-by-step guidance to NUS postgraduate students and researchers to cultivate deep tech entrepreneurs, to transform the university’s world-class research into their own deep tech start-ups.

Teams will undergo a one-year journey to be equipped with entrepreneurial skills and experience through workshops, mentorships, industry linkages and incubation support, to develop commercially viable and investible deep tech start-ups, generating a pipeline of up to 250 teams in five years. NUS will invest up to S$100,000 in start-ups demonstrating high commercial potential to accelerate their growth.

For more information, visit https://nus.edu.sg/grip.

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NUS Enterprise nurtures entrepreneurial talents with global mindsets, while advancing innovation and entrepreneurship at Asia’s leading university.

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