FAQ
What is UV light?
Ultraviolet (UV) denotes a band of the electromagnetic spectrum with wavelengths from 100 nm to 400 nm; shorter than that of visible light but longer than X-rays. UV radiation (UVR) is present in sunlight and makes up about 10% of the sun’s total light output. The electromagnetic spectrum of UVR can be divided into certain three ranges (see table).
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What is UV-C disinfection?
UV-C light is germicidal, also known as Ultraviolet Germicidal Irradiation (UVGI); electromagnetic radiation that can destroy the reproductive capacity of microorganisms by causing photochemical changes in nucleic acids, deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and proteins. Wavelengths in the UV-C range are particularly harmful to cells because they are absorbed by nucleic acids and proteins. The germicidal effectiveness ranges from 200 nm to 300 nm and peaks at about 260 - 265 nm, which corresponds to the peak of UV absorption by bacterial DNA.
Protein absorption leads to breakage of cell walls and death of the organism. DNA absorption of RNA is known to inactivate the DNA of RNA double helix strands due to the formation of pyrimidine dimers in DNA leading to mutations of cell death. Pyrimidines are molecular components in the biosynthesis process, including thymine and cytosine. Thymine and cytosine, together with adenine and guanine, are the four base pair components of DNA (see Figure 1). Thymine dimers are the primary dimers that are formed in the DNA by UV display. The lethal effect of UV rays is mainly due to the structural defects caused when thyme dimers form. If enough of these dimers are made in DNA, the DNA replication process is disrupted and the cell cannot replicate. It does not physically remove cells, but it kills the organisms and prevents them from propagating.
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Figure 1
UV-C works through line of sight, so light must reach a surface to kill bacteria or other microorganisms. Ultraviolet technology is a non-chemical approach (direct lightening) of disinfection. Nothing is added making this process simple, inexpensive and very low maintenance.
What is the effectiveness of UV-C?
UV-C has been used in water disinfection since 1900, and after that also has been widely used in air disinfection. UV is very effective against organisms because it “attacks” the DNA & RNA directly, which prevents organisms from becoming resistant.
What is log reduction?
When we talk about log reduction in the disinfection industry, this is about the reduction in the number of microbes. This reduction is always described by a factor of 10.
1 log reduction = 90% kill (1 in 10 survive)
2 log reduction = 99% kill (1 in 100 survive)
3 log reduction = 99.9% kill (1 in 1000 survive)
4 log reduction = 99.99% kill (1 in 10,000 survive)
5 log reduction = 99.999% kill (1 in 100,000 survive) = High-Level disinfection 6 log reduction = 99.9999% kill (1 in 1,000,000 survive)
7 log reduction = 99.99999% kill (1 in 10,000,000 survives)
A log (1) reduction means that of a certain number of microbes at least 90% are killed, out of ten a maximum of one survives.
A 6 log reduction therefore means that a millionth part survives or in other words the population is reduced by 99.9999%.
Advantages and disadvantages of UV-C?
What effect does UV-C have on materials?
The harmful effect of UV consists of the rays that pass through our ozone layer; so UV-A & UV-B. That’s why if you leave something in the sun a little too long it will become brittle. This is due to the hardening effect of UV-A and UV-B. UV-C has no harmful radiation on materials because it is blocked by our ozone layer.
What are the dangers for the environment?
UV-C is very dangerous for living things, including people and animals. This is because UV-C breaks the DNA & RNA of all organisms; this can cause people to go blind and develop skin cancer.
Are healthcare employees at risk from UV-C light?
No, because no radiation is released.
Which studies have been done?
Research has been done in the Streeklab Haarlem, Radboudumc and UMCG.
See also our clinical evidence page
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The tests with the D25 in a hospital setting have been conducted to demonstrate that UV-C light can be used for the disinfection of non-invasive medical devices in the intended environment. All tests were carried out with lamps that have undergone extensive stress tests. This is done to determine the performance of the D25 under the worst conditions, when the lamps are at the end of their lifetime. This always guarantees a validated and consistent disinfection cycle.
The performance of the D25 in hospital environments has been measured using “before and after” measurements on real-life non-invasive medical devices. Because it is not ethical to deliberately infect medical devices with microorganisms in patient environments and impose additional risks, the devices tested therefore entered the study after normal clinical use. The study protocol was then determined with a measurement before the disinfection protocol with the D25 and afterwards a measurement. The primary result of this study was the reduction in colonial forming units (CFU) measured after disinfection with the D25 compared to CFU before disinfection. The outcome of the study was a log-5 reduction in the clinical environment.
After hospital tests with the D25, the existing standard hospital disinfection protocols have been maintained. This never compromised patient safety, as the medical devices used in the test were still disinfected with the valid protocol in the hospitals. This exempted the study from ethical approval from the METC; medical ethics review committee.
Clinical trial design Radboudumc
The first hospital test was performed in Radboudumc in Nijmegen by infection prevention specialist Suzan Cremers- Pijpers and Microbiologist Joost Hopman in Q1 2019. In the study, more than 400 samples were measured for CFU activity on medical devices before and after disinfection with the D25. It was concluded that the D25 achieved a log-5 reduction on the test medical devices in the real clinical setting by a statistical comparison based on the total number of CFUs.
Structure of the UMCG academic test
The second hospital test was carried out in the University Medical Center Groningen (UMCG) in the Netherlands by infection prevention specialist and epidemiologist Mariëtte Lokate in Q3 2019.
The study tested 5 different highly resistant organisms on different materials;
Klebsiella pneumoniae (resistance to NDM-5),
Pseudomonas aeruginosa ATCC 27853,
Staphylococcus aureus ATCC 2921,
Enterococcus faecium (VRE resistance),
Citrobacter freundii ATCC 8090.
The conclusion is that the D25 is effective in killing organisms with log-5 reduction on smartphones, plastic, metal, glass, paper, Velcro, leatherette, VR glasses and agar.
However, the D25 is not effective on textiles, rubber and raw wood, as specified in the test report. Therefore, the IFU specifies that textiles, rubber and raw wood are not suitable for disinfection with the D25.
Set-up laboratory test Streeklab Haarlem
To demonstrate that UV-C light can be used for disinfection of non-invasive medical devices, the same standard, EN 14885: 2018, has been used as a reference point. The required log reduction and selected microorganisms were based on EN 14885: 2018 with the associated test standard.
All tests were performed with lamps involved in stress tests. This is done to determine the performance of the D25 under the worst conditions, when the lamps are at the end of their life. This always guarantees a validated and consistent disinfection cycle. In addition, the samples of organisms were placed on the bottom glass plate, top side up to have the longest distance from the lamps, thus the weakest UV radiation, imitating the worst conditions. Finally, the tested organisms were randomly placed on the disinfection chamber area to be approved for complete disinfection in the D25. The tests are conducted in a microbiology medical laboratory accredited under EN-ISO 15189: 2012. To prove the claims as specified in the use of D25 and to support and evaluate clinical performance and safety, the D25 was tested in accordance with table 3 on page 24 of EN 14885: 2018 in the following area of application: “surface disinfection without mechanical action” and “instrument disinfection”.
D25 performance has been tested on:
Bacteria
Yeasts
Fungi
Myco-bacteria
Tuberculosis
Spores and Viruses
Activities according to the relevant standard test methods as determined in table 1 on page 16 of EN 14885: 2018. This means that both steps of phase 2 (2.1 & 2.2) have been tested. In conclusion, the results of the tests prove that the D25 meets the claimed performance as specified in the claimed performance. In addition, these test results prove that the D25 performs even better than required by current standards. The UV Smart D25 has achieved a higher log reduction than the standard EN 14885: 2018 of chemical disinfectants and antiseptic wipes. Therefore, the same disinfection levels can be claimed as the prior art.
At the moment, more extensive testing for viruses is underway.
In which department was tested?
UMCG: ICU and cardiology.
Radboud: Internal medicine & infectious diseases
Which instruments were tested with?
In Radboud with DECT and Visi mobiles. In UMCG with many materials mobile phones, plastic, metal, glass, paper, Velcro, artificial leather, VR glasses and agar.
What is the intended use of the D25?
“The UV Smart D25 is intended to reduce micro-organism count by at least log-4 on outer surfaces of non-invasive medical devices and non-medical equipment within 30 seconds by using UV-C light. The device does not support or sustain life. ”
What are the dimensions of the D25?
Exterior dimensions (L x W x H): 470 x 445 x 275 mm
Disinfection chamber dimensions (D x W x H): 420 x 265 x 160 mm
What does the disinfection process of the D25 look like?
Has a risk assessment been carried out for each instrument that we claim can
be disinfected?
No; not with every specific device but on the materials. Instruments and equipment made from those materials can be disinfected with the D25.
Can you disinfect scissors, tweezers?
Yes, that’s possible. Non-critical and semi-critical instruments are suitable for the D25.
You can think for example of:
• Blood pressure belts
• Thrust belts
• Infusion pumps
• Thermometers
• DECT telephones
• Tablets
• Glucose meters
• Saturation meters
• Ventilation equipment • Nose speculum
• Suture scissors
• Reflex hammers
• Stethoscope
• Smartphones
Can VR glasses also be used?
Yes. See the UMCG test. D25 is effective in killing organisms with log-5 reduction on VR glasses.
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Which instruments are NOT allowed?
Critical instruments. Critical devices, such as surgical forceps, come in contact with blood or normally sterile tissue.
Is the D25 suitable for bulk disinfection?
No. Cleaning medical devices with the D25 takes 25 seconds. Because it can only hold a limited number of items per process, the D25 is not suitable for bulk disinfection.
How do I know what actually happened in 25 seconds? Is there a demonstrable
effectiveness of the process?
The D25 contains optical sensors that check every disinfection cycle whether sufficient doses of light have been released for successful disinfection. When the dose of light approaches the threshold, the device will indicate that maintenance is required. If no maintenance is performed and the dose falls below the threshold, the cabinet will switch itself off. In this way we prevent false safety.
As a second check, the cabinet counts the number of switches on and off of the lamps. Here there is a threshold value (which has been tested by UV Smart) of the maximum number of on / off switches. The device will first indicate that maintenance is required and then turn itself off if it does not.
As a third check, special UV disinfection stickers can be purchased from a 3rd party. When the stickers change colour, there has been sufficient UV-C light and the procedure has been validated (http: // intellego-technologies.com / hospital /)
Can we demonstrate process conditions?
There can be maintenance, emergency or control; data on all disinfection cycles are read.
What is the effect of fingerprints on the disinfection of the surface underneath?
There is no negative effect. The UVC light shines through that.
Is the D25 also mobile usable?
Yes, it can be delivered on a trolley, but this is an extra option.
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How do we prevent that all kind of objects are being put in the machine?
We offer training, IFU, instructional videos.
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What materials is the D25 made of?
The D25 contains a special mirror chamber (brushed aluminium) and special glass plates that lets UV-C through.
Can data be read? If so, which ones? And in what way?
Via USB port at the back; every disinfection cycle (successful and unsuccessful) can be viewed with all data: time, duration, dose of light, etc.
What if a lamp is broken?
Then the entire set of lamps does not turn on. And there is a second set of lamps that can take over the process; if a lamp breaks as well, the system switches itself off.
What if the power of the lamp decreases?
The tests were done under a “worst-case” scenario. Besides, there are sensors in the cabinet to check the correct dose. If the dose falls below the threshold, it switches itself off.
What about shadow areas?
The inside of the D25 is made of highly reflective material. This means that there is no shadow formation with closed objects. It is important not to place instruments against each other.
What is the lifespan of the D25?
5 years. It is delivered in the first year, after which annual maintenance follows a € 1,300 (= incl. Replacement of the lamps).
Is the maintenance and the annual replacement of the lamps dependent on the use in a year?
Yes, the bandwidth is 18 months, but with current usage, the lamps should be replaced within a year. The lamps last 60,000 times or 12 months (whatever comes first).
