UV LED for sterilization... will it work? which one(s)?

My longtime barber (who's since retired) had these ancient contraptions that looked much like toaster ovens, but with UV lamps inside. He would put his haircutting tools in these when not using them, and apparently it kept them sterile... at least to the point of not spreading critters or germs from one person's head to the next.

Now I want one! We have three kids... one likes to toss all the toothbrushes in the sink with soapy water in some vain attempt to wash them like dishes (he also washes his hands in the same water)... his younger brother has been known to leave his toothbrush on the floor, in shoes, under dusty furniture... even give it an occasional dip in the toilet (yech!)... I WANT THE BARBER SHOP STERILIZATION CONTRAPTION! WAAAAH!

Would a simple box with a high output UV LED be enough to sterilize toothbrushes and the like, and if so, which ones? Or which wavelength? I'm completely clueless on this, looking for some help.

Thanks folks! :bow:

http://www.hydro-photon.com/

One option that's kind of like what you're talking about - no LEDs, though, it seems to be fluorescent.

Probably way easier to make a box with fluorescent UV light, that's what we use to sterilize level 2 pathogens (along with ethanol), so must be good enough to clean your toothbrush.

But really, dip it in 70% ethanol for 20 seconds or so would work just as well and quicker.

I use 3w 385nm LEDs in my coral growing process. It has no negative effects on bacteria.

You require light in very short wavelegnths. UV-C does the best job, and UV-B can do mild effects. To my knowledge, no one has LEDs going lower than 355nm, which is still UVA and useless for killing.

You can buy germacidal bulbs for cheap on ebay. Some are very compact and small. I've used them in various aquariums for UV sterilizers over the years.

So, yes you could easily make the device you desire, however, LED's are not yet the path that will take you there. Perhaps in the future they will be created.

Best Wishes,
-Luke

In our computer lab, I use these two devices to sterilize the keyboards and mice. There's nothing better than a public computer keyboard to spread germs.

http://www.brookstone.com/store/pro...arch_words=UV&prodtemp=t1&cm_re=Result*R1C2*T

http://www.thinkgeek.com/gadgets/security/8f84/

Quick, portable, mess-free and very effective.

If you just want something for yucky toothbrushes:
http://www.amazon.com/dp/B0006VGZFC/?tag=cpf0b6-20

A man of your talents could easily fashion a box with a ballast and just purchase the bulbs:

http://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation

http://www.bulbtronics.com/technology/index-germ-1.html

If you build something, MAKE SURE you and your kids are not exposed to the light. A sunburn is painful. A burned cornea is excruciating.

-Chris, M.D., Ph.D.

milkyspit said:

Would a simple box with a high output UV LED be enough to sterilize toothbrushes and the like, and if so, which ones? Or which wavelength? I'm completely clueless on this, looking for some help.

Thanks folks! :bow:

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Well... anything less than 380nm will have SOME effect on bacteria... but you need to pound joules of UV into a flat surface in order to truly sterilize it (we're talking virus and yeast as well). Toothbrushes and the like, are even harder to sterilize... I would say that you're much better off with mercury-based fluorescents (w/o a phosphor) for providing the kind of intense short-wave UV that you want for a sterilization box. However, if you insist on going with UV LEDs, I suspect it might work, but would require a large number of LEDs.

I would say a small (1ft^3) box with 20-30 <380nm UV LEDs driven close to the max would probably work... but make sure they're arranged all around the box, since you're going to try to sterilize non-planar surfaces.

I would be curious to see if this box can do it... so if you're going to try building it, I could help you test its effectiveness, since I have access to a microbiology lab.

Another thing to think about is UV of that caliber will kill most plastic really quick, so plan on your toothbrushes turn yellow in a week and need replacement after a month if you go with UV route.

If it puts in enough energy you are also going to get ozone - most ozone generators are high-energy UV sources that get air blown past them. Ozone is not nice stuff - it is about 100x as toxic as hydrogen cyanide. Use a charcoal air filter on the air coming out of the box.

Likewise for nitrogen oxides, again not good things to have in the house. Again, seriously bad for you.

Use household bleach - cheaper, safer...

And more likely to work on something like a toothbrush.

Just rinse well after bleaching

Probably cheaper still to replace the toothbrushes.

dulridge said:

If it puts in enough energy you are also going to get ozone - most ozone generators are high-energy UV sources that get air blown past them. Ozone is not nice stuff - it is about 100x as toxic as hydrogen cyanide. Use a charcoal air filter on the air coming out of the box.

Likewise for nitrogen oxides, again not good things to have in the house. Again, seriously bad for you.

Use household bleach - cheaper, safer...

And more likely to work on something like a toothbrush.

Just rinse well after bleaching

Probably cheaper still to replace the toothbrushes.

Click to expand...

Based on that, I would stick with isopropyl.

LukeA said:

Based on that, I would stick with isopropyl.

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But still rinse thoroughly - isopropyl alcohol is not as safe as ethanol for ingestion.

Hence bleach, it is dirt cheap, strongly biocidal (most Legionaires disease outbreaks are caused by someone buying an expensive quaternary ammonium biocide instead of bleach) and easily available. It also lets you know about its presence (so you know to rinse it out) and does not contain a solvent that will attack most plastics as the low molecular weight alcohols will.

I used to work in water treatment in the early 80's - bleach is wonderful stuff and is essentially what was used (I believe they mostly use ozone in new plant but in very, very carefully controlled equipment) to make drinking water safe to drink.

When I lived in a place (15 18"S 23 09"E) where the water was far from safe (Dog that had died of rabies in the water intake anyone) I dumped small amounts of bleach in the drinking water and larger amounts in the bath water - however, I was a chemistry teacher there and could measure and control the concentrations easily.

Are you sure that you really need to do that, I mean are you going to sterilize them daily? I personally don't think that they would be that harmful.. Considerung that most germs will not live very long on a dry plastic surface and that soap water is not that friendly to the topotbrush as well.. With time you should be able to teach them to take better care of their brushes.

Plus if you find something really strong enough to kill all the germs hidden in the fibers, well as mentioned before, the UV will certainly damage the plastic. The alcohol idea wasn't so bad actually. That should be fine with the plastics..

What about running them through the dishwasher every now and then? If its good enough to clean stuff I eat off of, it should work to clean something I brush my teeth with.

I rinse my toothbrush and cup in mouthwash (listerine). It's pretty good at removing anything on my cup and I assume it's just as good at cleaning the toothbrush.

chocho said:

In our computer lab, I use these two devices to sterilize the keyboards and mice. There's nothing better than a public computer keyboard to spread germs.

http://www.brookstone.com/store/pro...arch_words=UV&prodtemp=t1&cm_re=Result*R1C2*T

http://www.thinkgeek.com/gadgets/security/8f84/

Quick, portable, mess-free and very effective.

Click to expand...

Wouldn't the reflected UV light off the keyboards and so on pose a hazard to people? Especially the hand holding the device since that would be the closest part of the body to the source of the light.

I use hydrogen peroxide to clean the kitchen sponge and soak my toothbrushes in it occasionally. I read its a good household cleaner because it breaks down easily and works effectively on bacteria. Anyone else use it?

I use peroxide, and I didn't give much thought to trying anything else. Wonder why?

UV-C wavelength (the shortest of the three UV sub-bands) generating water purification devices have been used for a few years now by some light/ultralight backpackers.

i have both of the most popular units marketed to my crowd.

Steri-Pen and AquaStarPlus are the devices.

one key to UV-C purification is that all surfaces to be treated must be directly exposed to the UV-C light. hence, for backcountry water purification, the water should NOT be turbid and is often passed through a pre-filter to remove larger debris which harbor biofilm and large quantities of lil' buggers.

hence, both of these devices require that the water be swirled during the treatment process.

you would need to drop your toothbrushes into a vessal filled with water, or in the case of the AquaStarPlus, drop your toothbruses into the included 1L Nalgene bottle, and swirl either the Steri-Pen or the entire Nalgene with the AquaStarPlus cap on it.

for your application, the AquaStarPlus would work better, IMO.

treatment times are on the order of 90sec.

you would need to be sure that the toothbrushes are swirling also in order to expose all of their surfaces to the light.

w/o performing before and after microbial testing of the toothbrushes, i can't really say how well this process would work. but, i can no longer do this as i no longer work in the medical field and so don't have a micro-lab available to me.

keep in mind the modus operandi of UV-C light. it doesn't remove the lil' buggers. it denatures/scrambles their DNA so that reproduction is NOT possible. while NOT really an issue, unless your kids think about swallowing 'bout a gazillion (that's a really big number!!) of the lil' critters. ~6hr exposure to sunlight (even through a typical plastic bladder or bottle carried by some backpackers) will accomplish the same via a process termed SODIS (solar disinfection).

both of the popular backpacking UV-C devices perform best on Li batts (but then y'all here on CPF have already guessed this by now).

water should NOT be too cold or the devices won't operate (they warn the user of this).

in the field, these devices occasionally mis-operate for a number of reasons. they warn the user of this though via LED-signaling - water too turbid being an exception to this notification process.

i agree that ET-OH would work - cheaper, less problematic as regards treating all surfaces. personally, i use Listerine for this purpose.


if you have more specific questions related to microbiology, pathogens, cleaning toothbrushes, or related issues, feel free to PM me.


p.s. BTW, i'm the proud original owner of Gotham #17

does anyone know if a regular LED lght puts out enough UV to be harmful?....I have the 1W task Force 1AA light and am thinking of using it in patient s' eyes to check pupil reactions ( so exposure time would be only a few seconds, but obviously it wouldn't be a good idea if it might be harmful).....any thoughts??

umberto said:

does anyone know if a regular LED lght puts out enough UV to be harmful?....I have the 1W task Force 1AA light and am thinking of using it in patient s' eyes to check pupil reactions ( so exposure time would be only a few seconds, but obviously it wouldn't be a good idea if it might be harmful).....any thoughts??

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A quick look at some of the spectra over on LED Museum shows that white LEDs stop well short of UV.

another UVaquastar user here... works great!
used it for two weeks at Philmount dipping water from streams.
didn't get sick...

I'd be wary of any device that didn't shield all UVC within.
plastic bottle UVaquastar uses is opaque to UVC.

here's a pic of florescent tube from UVaquastar proto