Our project is to create a handheld device that is effective to many pathogens, including SARS-CoV-2
Updated: Dec 31, 2020
In the Covid-19 pandemic situation, a lot of people have been profited off by the fear of an unknown virus. And there are a lot of devices using germicidal radiation technology that falsely claim they actually work.
Nowadays, there are two kinds of germicidal products that are both using UVC range radiation:
1. UVC lamps
2. UVC LEDs.
Their output power plays a big role in the effectiveness of inactivating pathogens. And UVC lamps are usually stronger in terms of output power than UVC LEDs.
UVC lamps operate with toxic mercury vapor. It needs to be handled with extra care as if the lamp cracks, the toxic vapor can cause serious health problems. They also require warm-up time from a min up to 5min depending on the power output. So you need to wait every time up to 5min before using the UVC lamps. Other than that, UVC lamps are radiating all angles, meaning most of the energy is wasted before reaching the object you want to disinfect. The wasted energy is likely to reach your body if you are nearby the device. As a result, UVC lamps are not very suitable for personal daily usage.
UVC LEDs seem like a good option as they do not contain mercury and have the advantage of being small in size; safer due to the radiation being emitted directionally instead of 360 degrees. However, good UVC LEDs are expensive. The LEDs with higher output power (for example from 30mW to 80mW) are even more expensive. Most of the existing devices using UVC LEDs are very weak (less than 5mW) that one can say they don’t even work. Don’t believe me? Check amazon, you cannot find UVC LED devices showing the brand or model of the LEDs are being used or their power output. Why? Maybe because they think you will not do the research on how much dose is needed for killing different pathogens. Instead of giving you a 3-4 times more expensive UVC LEDs, they can just earn more money and people who are afraid of the pandemic situation will buy anyways.
We want to put some standards for the technology as UVC can really help us in a lot of different ways: other than disinfection that can help decrease the chances of getting sick, the environment can be also helped by reducing waste.
First of all, we need to identify how much dose is considered working for killing germs. There are a lot of factors that can affect the effectiveness of UVC radiation, for example, the humidity and wavelengths. A 222nm radiation is more absorbed by water than a 265nm radiation meanwhile 265nm is about 20% more effective than 254nm radiation to the RNA of viruses [A], etc. There are numerous studies that can give us some ideas of the dose needed to inactivate germs:
With the above studies show that Covid-19, the virus with ssRNA and one of the easiest to be inactivated, required 5.1mJ/cm2 of dose with 265nm radiation while other studies are supporting approximate from 2.5mJ/cm2 to 8mJ/cm2 dose depending on the wavelength. At the same time, many kinds of pathogens require similar doses to be inactivated while there are some like Calicivirus which require around 20mJ/cm2 to be inactivated.
Secondly, the LED brand and model should be shown with the product description so we can check if it is reliable and powerful enough. No one wants to buy a device holding in your hand for 10 minutes to just disinfect a phone or mask. We are co-operating with one of the biggest UVC LED manufacturers, Klaran. By making use of their 60mW 265nm LED (KL265-50U-SM-WD), we successfully created our device that reaches 5.1mJ/cm2 of dose in 6sec at 5cm distance (3sec at 3cm distance).
One of the limitations of radiation is that it is difficult to disinfect the shadow area. By having a small handheld UVC device you can freely adjust the angle without exposing to the radiation. Therefore, ensuring the object is nicely disinfected.
We further improved the design by using a reflective coating and lens. Inspired by the idea of laser pointers, the UVC radiation is concentrated by an angle of 130 to 90 degrees. Hence the effectiveness is boosted up further by at least 300% than before meanwhile decreasing the risk of UVC exposure to your body.
All in all, we successfully made a device that solves big problems and is superior to the existing UVC devices. It is powerful (Log3 reduction of Covid-19 in 6sec at 5cm distance), small enough to put inside your jeans pocket and safe to use.