You might be right. Maybe its harder than I thought. I’m curious though, what did you build? And how did you attempt to test it?
I wouldn’t do that for several reasons:
- As you know UV-C is dangerous for the eyes and skin. This includes you and other people around.
- UV-C produces ozone, which is also harmful
- UV-C breaks chemical bonds, exposed surface might age and degrade faster.
- UV-C does not instantaneously sterilize surfaces. You need to keep shining the light on the surface for some time to kill everything. Also, microbes may still survive in asperities where the light didn’t reach.
- If there is any dirt, dust, or bio-film the microbes are much harder to kill.
It is much easier to:
- Wear gloves when you know you will touch infected surfaces like door handles
- Use your knee or elbow for crosswalk buttons
- Wash your hands. Soap kills microbes much more reliably than UV-C
- Use disinfectant whips.
Unfortunately UV-C is far from being a “magic bullet” that will keep the world safe against microbes. In fact it does more harm than good in most conditions.
To test for UV-C, Sunburn a banana. UV-C LEDs, Questionable.
All the Best,
Jeff
What do you think about those Steripens that use UV to sterilize water and toilet seat wands?
I think the manual says you need a really clean water for it to work/.
Is it just a scam?
I don’t know much about sterilizing surfaces with UV-C, but lexel has some drivers that would work for building a light.
Building a UV-C flashlight is not actually difficult - it just looks like a high V_fwd LED. There are lots of drivers (with the appropriate voltage and current) which can drive UV-C LEDs. The tricky part is to get the appropriate UV-C LEDs at reasonable costs. Sub 280nm LEDs are available, but 265nm and lower wavelengths begin to get very expensive, tens of dollars per LED, increasing significantly for higher power levels. Side note - this also means most of the 'cheap' UV LED 'disinfectant lamps' you can get on Aliexpress etc, are not actually germicidal, and produce UV in the higher wavelengths (>300nm) which would not be anywhere near as effective as true 265nm or lower UV-C light.
In addition to all the dangers described above, even if you're looking to disinfect surfaces with such a flashlight, you're looking at tens of minutes to achieve proper sterilization, which I assume would render such a device too expensive for limited practicality. I'm pretty sure you wouldn't want to be waiting around your door knob for 10 minutes shining a light on it before opening the door! Water sterilization with UV is different since the water is continuously exposed to UV for a long duration of time.
Best wishes and stay safe!
It looks like it takes between 50 and 150 mJ/cm^2 to disinfect different bacteria, spores and viruses by a factor of 10^4. (Search “uvc dose to disinfect”, informative PDF is second hit)
So for a light with 10 10mW LEDs, say 60mW can be concentrated into a 5cm spot, so 20cm^2. That makes 3 mW/cm^2 intensity. So to give that 5cm spot a 100mJ/cm^2 dose it would take 33 seconds. Not too bad.
With the UVC steripen it disinfects a liter of water in 90 seconds.
you can carry a cosmetic spray bottle with like 10ml with some disinfection fluid in it in your pocket and a cloth to wipe it off
UC-C does not only kill bacteria and viruses it also very effective kill any cells of your body exposed to it
Thank you guys for explanation.
I think the water has to be perfectly clean though, any dirt that is in the way of the UVC will influence the results.
I wonder how that works with materials other than water, the UVC could just bounce off the dirt before it disinfects what’s behind the dirt?
I always doublt it, about the so call portable uvc sterilizer, does it really work as the manufacturer said?
They have UV-C light wands available on Amazon for about $50. My company bought a bunch for it’s employees when we returned to work. Usb rechargeable. From everything I have researched, they work well.
That is toooo expensive. according to my knowledge, $10 is enough to buy those UV-C light. on Alibaba.com
Sometimes you get what you pay for.
That makes sense. You are right. May I see which UV-C light you bought ? Could you kindly give me the link on Amazon ?
I can’t link it without linking my Amazon account and that’s not going to happen lol. But I did find it, you can search Lovcoyo uvc wand. My employees have been using it for a few months now and we have had zero issues.
Handheld device is not safe, you need to protect skin and eyes and possibly lungs.
i second that. 10-15 bucks will get you 8w uvc fluorescent light. i have 2 of those in my bathroom, i put them on for 15 min, and they remove all smells. including cat litter box. it makes ozone. which is good, it kills germs inn far more places than just surfaces. it takes 5-10min to ventilate the bathroom from ozone. those led sanitizing lights are scams. a good led of 254nm and lower are 10 or so bucks, and it has fraction of a watt.
Could you post a link for your setup? Would this work for a bathroom?