Frequently Asked Question

The inspiration for Sterly came at the beginning of the COVID-19 outbreak. Many businesses, including MIACO Plus, were highly affected by the pandemic. As a result, we began to research what could be done to improve the situation. Combining our knowledge of Physics and Electrical & Electronic Engineering, we came up with the idea for a portable but powerful UVC sterilizer for everyday needs, surpassing the power of the existing devices that utilized the UVC technology. From then on, we focused all our time and energy on digging into every single aspect of the theory, electronics, and practical usages of UVC. And now we proudly present you Sterly, the UVC flashlight that is the ideal solution for fighting the germs that surround us.

UVC refers to the invisible light with wavelength 100nm to 280nm. For disinfection purposes, UVC with wavelength from 100 – 200 nm will produce toxic Ozone in the air. 265nm UVC is considered the most effective as DNA and RNA absorbs its energy the most. UVC energy is absorbed by nucleic acids inside the RNA and DNA of the microbes, resulting in covalent bonds which at the right dose can render the pathogen unable to reproduce and infect. The principal way UVC inactivates a pathogen is the creation of Thymine dimers within the cell DNA – which has a demonstrated peak absorption of 260 nm.
Why are these absorption spectrums slightly different across pathogens? This change is the result of cellular protein, specifically the presence of aromatic amino acids. UV Dose is the amount of UV radiation a microbe is exposed to and depends on the intensity of UV radiation and exposure time. A number of biological studies have produced widely accepted typical UV dose requirements for most common target microbes in disinfection.

According to two recent studies, the answer is ‘Yes’. The percentage of pathogens inactivation depends on the radiation dose received.

The effects of UVC dose, viral nucleic acid type (single-stranded RNA, ssRNA; single-stranded DNA, ssDNA; double-stranded RNA, dsRNA; and double-stranded DNA, dsDNA), and relative humidity on the virus survival fraction were investigated. For 90% viral reduction, the UV dose was 1.32 to 3.20 mJ/cm2 for ssRNA, 2.50 to to 4.47 mJ/cm2 for ssDNA, 3.80 to 5.36 mJ/cm2 for dsRNA, and 7.70 to 8.13 mJ/cm2 for dsDNA. For all four tested viruses, the UV dose for 99% viral reduction was 2 times higher than those for 90% viral reduction.
Scientists now are still studying the properties of COVID-19. What we know is COVID-19 is a coronavirus which contains ss-RNA, hence we can estimate how much dose needed to inactivate it. For example coronavirus SARS-coV-2 contains ss-RNA and Sterly needs 3sec to inactivate ssRNA virus within 5cm distance.
REFERENCE 1 REFERENCE 2 REFERENCE 3 REFERENCE 4

The UVC LED Sterly use is Klaran KL265-50U-SM-WD LED

  • Phone: phone surface contains the following germs: Streptococcus, MRSA and E. coli. To inactivate streptococcus, on average you need 5sec.
    REFERENCE
  • Mask: While different viruses and bacteria need different doses for inactivation, on average it is about 5 seconds within 5 cm distance. The closer it is, the higher the UVC dose, hence, shorter time for disinfection needed. Once disinfected, the mask can be used again. (According to CDC and the University of Nebraska developed an N95 Filtering Face Mask Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse (source), UVC can be used for masks disinfection without damaging the material of the masks. REFERENCE). Also, Sterly can sanitize the bacteria inside the mask that cause bad smell.

Sterly can greatly increase the reusability of masks, whether they are surgical masks or reusable masks, without destroying the material’s filtration properties. This means the biomedical waste from used masks can be reduced significantly.

Sterly also provides a much better experience for people who need to wear masks for extended periods of time, as it can eliminate bad odors inside the masks. Fewer new masks are being used as a result.

Reference: NCBI journal article.

It is strongly advised that a user never uses Sterly pointing towards one’s skin or eyes.
UVC is highly absorbable by different materials. It is not reflected by normal mirrors. Also, the torch design and an obvious piloting light can ensure the UVC is emitted towards one direction and easy to spot.

There is a strong visible light indicating the UVC light and a user can easily spot the visible light outdoors.
If you want to check if the invisible UVC is working, the following are the simple methods.
Using Sterly towards an A4 paper
Using Sterly towards a banana skin. It turns purple after 1min of UVC exposure
Using Sterly to sterilize the inner part of a used mask. The bad smell of the mask will be gone instantly
Using Sterly to a cut orange. The orange can be kept days even a week longer.

With 5cm distance Sterly can inactivate germs on average in 5 – 10 seconds. The time needed to disinfect germs decreases significantly with a closer distance. With 3cm distance Sterly requires around 2-4 seconds

As Sterly is a powerful device. We strongly recommend you not to use Sterly for more than 5min of continuous disinfection.

No, UVC will be absorbed by mostly all kinds of surfaces and no reflection can occur. Video showing for the dose of UV pointing to a mirror.

For many years, UV mercury lamps were considered to be the best choice. However, lamps have several limitations, including low activity at refrigeration temperatures, fragile construction, long warm-up time, risk of mercury exposure, and limited UV emittance at 254 nm. On the contrary, UV light-emitting diodes (UV LEDs) do not contain toxic mercury, work instant and emit at optimal UV wavelength of 265nm for disinfection. UVC LEDs are compact, durable and well suited to battery powered operation for point-of-care tools and mobile healthcare equipment.

No, UVC will be normally absorbed by glass surfaces and no or very less reflection can occur. Video showing for the dose of UV pointing to a glass mirror.

Most materials won’t reflect UVC. The common material that can reflect UVC are e-PTFE, Aluminum and Stainless steel.

REFERENCE

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