The Science behind KeySAN

Our KeySAN device has been specifically designed and manufactured for the use on musical keyboards. One of the driving forces behind the innovation of this device has been to support musicians getting back to playing instruments safely, during a pandemic where COVID-19 is still in the community.

Below we explain a bit more behind the use of the science and technology of the device to help you better understand how it works.

What is Ultraviolet (UV) Light?

There are seven types of electromagnetic radiation, which are broadly classified as follows:

  1. Gamma radiation
  2. X-ray radiation
  3. Ultraviolet radiation (UV)
  4. Visible light
  5. Infrared radiation
  6. Microwave radiation
  7. Radio waves

The spectral range of UV light is, by definition, between 100 and 400 nano metres (1 nm = 10-9m) and is invisible to the human eye. It sits between visible light and x-rays.

Using the CIE classification, the UV spectrum is subdivided into three bands:

  1. UVA (long-wave) from 315 to 400 nm
  2. UVB (medium-wave) from 280 to 315 nm
  3. UVC (short-wave) from 100 to 280 nm

UVC is totally absorbed by atmospheric ozone, has minimal penetration to the surface of the Earth and thus has little effect on human health. 90% or more of UVB is absorbed by atmospheric ozone, while UVA passes through the atmosphere with little change. Thus, the solar ultraviolet radiation of importance to human health consists of UVA and UVB. However, UVC can be created artificially by various means.

Why do we use ultra-violet light as the sterilising effect?

The reason we look to UV light as a steriliser is because the UV-C band has a strong germicidal effect however, there are some health precautions to consider.

Erythema and Conjunctivitis can be caused by UV-C light, which is why when germicidal UV-Light lamps are used, it is important to design systems to prevent UV-C leakage and avoid those damaging effects.

What do we do to protect device users from UV-C light?

People should ordinarily avoid exposure to UV-C as a matter of course. Fortunately, this is relatively simple in day to day life, as UV-C is easily absorbed by most products or surfaces – even standard flat glass absorbs all UV-C.

UV-C is mostly absorbed by dead skin, so developing erythema can be limited by the body’s own natural defences. In addition, UVC does not penetrate to the eye’s lens; nevertheless, conjunctivitis can occur and though temporary, it is extremely painful (and the same is true of erythemal effects).

In order to add extra protection for our users, on top of the soft fabric covering to limit UV-C light leakage and our warning system which alerts you if the device is not set up correctly, we also include a pair or protective glasses with each device sold.

How does UVC destroy bacteria and viruses?

This is where the science comes in! The high energy from short wavelength UV-C light is absorbed in the cellular RNA and DNA, damaging nucleic acids and preventing microorganisms from infecting and reproducing.

UVC is strongly absorbed by RNA and DNA bases leading to molecular structural damage via a photodimerization process. This results in virus inactivation, so that they are no longer able to replicate.

The amount of inactivation is directly proportional to the UV-C dose used and this, in turn, is the result of its intensity and duration of exposure. The farther away you keep an object from the light source, the less UV-C will reach the target, so only a quarter of the UV-C remains effective when the distance doubles.

The UV light emitted by a source is expressed in watts (W) and the irradiation density is expressed in watts per square meter (W/m2) or miliwatts per square centimetre (mW/Cm2). For germicidal action – dose is very important.

The dose is the irradiation density multiplied by the time (t) in seconds and expressed in joules per square meter (J/m2) or miliJoules per square centimetre (mJ/Cm2) . (1 joule is 1W.second).

The most common source for generating UV-C is the low-pressure mercury discharge lamp, where on average 35% of input watts is converted to UV-C watts. The radiation is generated almost exclusively at 254 nm viz. at 85% of the maximum germicidal effect and 80% on IES curve.

For our KeySan device, we use an LED light source generating UV-C at 275 nm.

Does UV-C light destroy coronaviruses?

In the table below, we have shared the data which has been gathered over the years to establish what dosage levels of UV-C have killed various coronaviruses.

The dosage levels indicated which are required to eliminate different viruses summarises the results of studies that have been performed on coronaviruses under ultraviolet light exposure. You can see the specific viruses test in each case. The D90 value in the middle column indicates the ultraviolet dose for 90% inactivation.

Boston University published specific data in June 2020 with regard to the Covid-19 virus, which establishes the D90 dose rate at 5 Joules/m2 and a rate of 22 Joules/m2 to achieve an elimination rate of 99.9999%.

The timing device in KeySan has been set to deliver a dose of 22 Joules /m2.

In studies (Linden et al 2007) it has been noted that the specific UV spectrum has relatively minor or insignificant effect on the dose rates. The rates in the table below were determined for the most part by low pressure or medium pressure mercury discharge lamps.

In this video we discuss the science behind the KeySAN UV-C device.

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