# UV LED's for sterilization???



## phreeflow

Hi All, 

Thought I'd revisit the great folks here at CPF in hopes that you some of you geniuses (seriously) could help me answer this question. 

I've seen people use Ultraviolet lights to sterilize various things such as water. So....I'm wondering if I could use UV Led's to accomplish the same thing. 

What I'm confused about is what part of the Ultraviolet lights makes it able to sterilize things? Is it the wavelength, spectrum, frequency, color, etc, etc. 

Please enlighten me!!
Thanks all!!!


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## Alaric Darconville

phreeflow said:


> Hi All,
> What I'm confused about is what part of the Ultraviolet lights makes it able to sterilize things? Is it the wavelength, spectrum, frequency, color, etc, etc.



The color of light is directly related to its wavelength. Or to its frequency. (These two are directly related to each other and are based on the speed of light through a vacuum). Raising the frequency shortens the wavelength, and lowering the frequency increases the wavelength. Typically, though, we discuss the wavelength of a particular light, rather than the frequency.

254nm UV has (in the UVC range) is particularly effective in sterilization, because it breaks up the DNA in microorganisms. It has a quantum energy of 4.9 electron volts per photon. 

254nm LED's are somewhat rare, though, and usually mercury vapor lamps are used to make germicidal lamps.


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## drmaxx

DNA has the property that it absorbs light around 260 nm very well. This means that if you provide enough light at 260 nm then the DNA will suck up too much energy and eventually break. The genetic information in bacteria and viruses is then destroyed and the bug dies. 

UV-Disinfection therefore depends on the frequency (the closer to 260 nm the better), the intensity (lots of light) and the fact that the bugs need to be exposed to the light (clear water is perfect). 

All I know is that right now there is quite some research done to actually develop LED based UV disinfection.


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## dbvanhorn

Does anyone know what is being used in the "Steripen"?


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## MattK

The Steripens use a flourescent tube. 

UV LED sterilization isn't economically feasible yet because the LED's that operate in the correct nm range are very expensive.


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## JohnR66

If you want to tinker, you can buy a little 4 watt germicidal tube that fits in a those battery operated fluorescent lamps.

The light produces some ozone and can break down/yellow some plastics (hold a piece of polyethylene over it and notice the odor) and make certain minerals glow. Hold your hand over it for a second and smell. You notice the burnt smell from the radiation breaking down the oils on your skin. The radiation from the light is ionizing so can be considered dangerous. Protect your eyes using a filter. Clear plexi will work. Clear glass lets wavelengths above 310nm through so is not completely safe.


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## dbvanhorn

MattK said:


> The Steripens use a flourescent tube.
> 
> UV LED sterilization isn't economically feasible yet because the LED's that operate in the correct nm range are very expensive.


 
Interesting.. I seem to remember digikey carrying tiny UV tubes at one point. I was tempted to do an EPROM eraser with one, but never bothered with it.


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## drmaxx

JohnR66 said:


> If you want to tinker [...]: Protect your eyes.


Don't ignore this piece of advice from John!


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## Kestrel

phreeflow said:


> What I'm confused about is what part of the Ultraviolet lights makes it able to sterilize things? Is it the *wavelength*, *spectrum*, *frequency*, *color*, ...


 
My deepest and sincerest apologies, but I just couldn't resist:

Yes.


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## MattK

LOL

X=X=X=X


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## phreeflow

Kestrel said:


> My deepest and sincerest apologies, but I just couldn't resist:
> 
> Yes.


 
:sigh: Yeah, yeah...whateva...I never said I knew anything about this stuff. I'm a NOOB :naughty:. Go ahead and take your best shots and get it off your chest.

However, I do have a specific application I'd like to experiment with and I need your help. 

When you say expensive, just how much are these 260nm UV LED's and where can I get them? If I'm understanding you all correctly, as long as the light source puts out enough light at around 260nm, then it should be able to disinfect organics...am I right?

If that's the case, could I just paint/coat these LED's with something to get it to output only 260nm? Thanks again fellas...:twothumbs


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## cdosrun

Phreeflow,

LEDs produce light of a specific range of wavelengths based on the substrates used and the transition energy therein. Essentially then, a red LED produces red light, it isn't like a light bulb being filtered. White LEDs and some less commonly coloured ones do use a phosphor coating to absorb the coloured light produced by the LED and radiate at a different wavelength (colour); the problem with this being efficiency, the output after the phosphor is less than before. In addition, producing a higher energy light (shorter wavelength, high frequency, more UV) from a lower energy one (i.e. frequency multiplying, albeit in fractions) would mean that the output would be very low.

It isn't really possible to do what you are after with any ease, the best option would be to look at the cost of the correct diodes. I think the Nichia ones in the region of 260nm are quite good, I have one at 265nm (from memory) but they output is reasonably low and the cost was high (around £10).

In air, the main germicidal element from UVc is formation of ozone; it is a free radical and serves to denature proteins quite viciously, hence killing organics.

It wouldn't, however, surprise me if they have made 260:280nm LED based specs for analysis of DNA/RNA ratios though.

Andrew


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## phreeflow

cdosrun said:


> LEDs produce light of a specific range of wavelengths based on the substrates used and the transition energy therein. Essentially then, a red LED produces red light, it isn't like a light bulb being filtered. White LEDs and some less commonly coloured ones do use a phosphor coating to absorb the coloured light produced by the LED and radiate at a different wavelength (colour); the problem with this being efficiency, the output after the phosphor is less than before.


 
Thanks for the great info Andrew. The light that I'm after doesn't necessarily need to be high output. It will only be about a cup or so of liquid that I'd like to disinfect so I'm hoping that maybe 1 or 2 leds would work in such a small volume. 

You brought up an interesting point that I was considering. Would it be possible to coat the LED's with some sort of paint or put the LED behind some sort of lense to get the right wavelength??? Even if the output dropped, couldn't I then just use multiple LED's to get the sterilization?

Thanks


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## phreeflow

drmaxx said:


> DNA has the property that it absorbs light around 260 nm very well. This means that if you provide enough light at 260 nm then the DNA will suck up too much energy and eventually break. The genetic information in bacteria and viruses is then destroyed and the bug dies.
> 
> UV-Disinfection therefore depends on the frequency (the closer to 260 nm the better), the intensity (lots of light) and the fact that the bugs need to be exposed to the light (clear water is perfect).
> 
> All I know is that right now there is quite some research done to actually develop LED based UV disinfection.


 

I looked around and found a company producing UV LEDS in the 390-405nm range. Are these too far off from 260nm to be effective in sterilization. 

thanks again!


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## MattK

Yes. You need to find them in the 260nm range - I think Nichia is your best bet but they're scary expensive if you can even find a source to sell you small quantities.


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## jerry i h

+1. Even those 365-385 UV nm money/crime scene detectors miss the mark by a country mile; not even close. 
Steripen only work for virus and bateria. So, it WILL take care of Giardia (back packer's diarrhea, since it is a bacteria). They will NOT neutralize things like: household chemicals, pesticides, petroleum spills, heavy metals. What I am afraid of is that during a natural disaster, someone will take one of those money detector things, zap a cup of contaminated water for a minute, and figure it is now safe to drink. NOT. Not only is the wavelength totally wrong, it won't take care of all those nasty chemicals :sick2: even if it were of the correct wavelength.


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## phreeflow

Hi all, 

I just got off the phone with SSC, Nichia, and Cree. 

Apparently, Cree has decided not to make anymore UV dies from what I am hearing. They've pushed it back for one year but it doesn't seem likely that they'll be carrying that product anymore (but don't quote me on it). In any case, they were 390-405nm.

Nichia still has 365-385nm but no longer carries anything in the 260nm range. BTW: I couldn't believe the prices. This led, #NCSU034AT-E costs over $200! While NSSU100a is more reasonable at around $1-$2. 

SSC doesn't even deal with these at all. One of their branches Seoul Opto Devices may carry them but it's not worth a call to Korea. 

Bottomline: Like Jerry said above, don't drink water "sterilised" by one of these LED's...totally wrong frequency. UV LED's at shorter wavelengths are as MATTK put it, way too expensive to be economically feasible for sterilisation. 

Thanks to all for the education and input!! This has got be one of the best forums!:rock:


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## Marduke

Why not just use the Steripen to begin with?


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## MattK

Yes. As their official battery supplier I am 100% in agreement.


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## Marduke

MattK said:


> Yes. As their official battery supplier I am 100% in agreement.



+1 for a totally non-biased opinion....


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## drmaxx

phreeflow said:


> However, I do have a specific application I'd like to experiment with and I need your help.


If you find a good and reasonalbe cheap and reliable solution then you're in for quite a large business.

The WHO acknowledges treatement at the point of use as one of the most important measures for improving health worldwide. Even in developing countries there are substantial concerns about hygenic problems that occur within the water system of a house. E.g. Legionella that cause legionellosis or Legionnaires' disease is quite a concern over here in Europe.

A UV-LED that would disinfect the drinking water at the point of use and would run for a long time and would be big business.


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## dbvanhorn

phreeflow said:


> :sigh:
> 
> If that's the case, could I just paint/coat these LED's with something to get it to output only 260nm? Thanks again fellas...:twothumbs


 
In case this wasn't already made clear: No.


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## phreeflow

drmaxx said:


> If you find a good and reasonalbe cheap and reliable solution then you're in for quite a large business.
> 
> The WHO acknowledges treatement at the point of use as one of the most important measures for improving health worldwide. Even in developing countries there are substantial concerns about hygenic problems that occur within the water system of a house. E.g. Legionella that cause legionellosis or Legionnaires' disease is quite a concern over here in Europe.
> 
> A UV-LED that would disinfect the drinking water at the point of use and would run for a long time and would be big business.



Hey DrMaxx...you hit the nail on the head. That's kind of along the lines I was thinking but the technology is just not ready as far as LED's go. For those of you recommending Steripen...I'll be getting one for personal use but I had an industrial application in mind when first initiating the question. I wanted to add uv led's to supplement something I am working on but have decided to just go with the uv tubes.



dbvanhorn said:


> In case this wasn't already made clear: No.



Actually it wasn't thoroughly touched upon on this thread and I thank you for the clarification. And you're 100% right, the folks at SSC said they had tried all sorts of different lenses and/or filters but they will not change the frequency.


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## gillestugan

There is a lot of research going on as a cheap UV-C LED would be perfect for water purification in development countries. 

LEDs would make it possible to make a small portable solar cell driven water purifier which needs no maintenance.


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## drmaxx

gillestugan said:


> There is a lot of research going on as a cheap UV-C LED would be perfect for water purification in development countries.


Not just in in developement countries. Legionella for example requires that we here have to keep our hot water tanks at home at 60 °C. This is one one hand a potential burn threat e.g. with kids and one the other hand costs a lot of energy. Give us a reliable way to disinfect the tap water and you are in business - I am talking here about most of Europe.


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## phreeflow

gillestugan said:


> There is a lot of research going on as a cheap UV-C LED would be perfect for water purification in development countries.
> 
> LEDs would make it possible to make a small portable solar cell driven water purifier which needs no maintenance.



Exactly...and a chance to do something good. It's unfortunate that one of the leading causes of death in many developing nations is poor water. It's literally like drinking poison.


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## Wangstang

Any chance there has been some advancement in the UV LED's that put light out in the proper range?

Wes


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## 1 what

FYI .... LedSupply list a 361nm UV LED for $3.99.
http://ledsupply.com/l5-0-u5th15-1.php
I think it sounds too good to be true but ordered a few of them last week. I expect delivery this Friday.
I'll let you know how they perform.


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## KiwiMark

1 what said:


> FYI .... LedSupply list a 361nm UV LED for $3.99.




It' a pity they don't have a 260nm UV LED for the same price (or even or twice the price).


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## AW

Seoul makes the 255nm UV LED for germicidal and medical applications :

http://www.socled.com/en/product/prd/DeepUVLED255.asp


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## 1 what

Hi AW!
Do you know anyone who sells them at a "retail" level?


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## SilverFox

Hello Phreeflow,

I am going to move this discussion over to the LED section of the forum.

Tom


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## Wangstang

> Seoul makes the 255nm UV LED for germicidal and medical applications :
> 
> http://www.socled.com/en/product/prd/DeepUVLED255.asp


 
Anyone know whot to talk to about building some 6P drop in bulbs?

Wes


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## travelinman

Not to be a nit picker here, but UV light doesn't actually kill bacteria, it only inhibits it's ability to multiply, thereby stopping it's ability to reproduce. Sort of a miniature vasectomy. oo: That's good enough however, because a few bacteria won't hurt you, it's only when all the offspring start having offspring etc. etc. that you get harmed.
At least that's what I learned in biology many many years ago.


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## drmaxx

travelinman said:


> Not to be a nit picker here, but UV light doesn't actually kill bacteria, it only inhibits it's ability to multiply



This is only partly correct. UV light damages the DNA - very unspecific. Some of this damage inhibits important life functions, some of them inhibits growth and multiplying. The key is, that the UV-dose is high enough to damage enough DNA to overload the internal repair mechanism. And this is equal to being dead. Otherwise the microbes are only harmed and require some time to repair themselves. After that they are ready to do their thing again. This is one of the reasons why UV-disinfection has a bad rep in water supply. If you don't do it correctly then you don't really disinfect. Doing it correctly is not an easy thing to do (Computational Fluid Dynamics - anybody?).


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## Rexlion

travelinman said:


> Not to be a nit picker here, but UV light doesn't actually kill bacteria, it only inhibits it's ability to multiply, thereby stopping it's ability to reproduce. Sort of a miniature vasectomy. oo: That's good enough however, because a few bacteria won't hurt you, it's only when all the offspring start having offspring etc. etc. that you get harmed.
> At least that's what I learned in biology many many years ago.


 I'm sorry, it just doesn't work that way. Stop shining that UV LED into your pants, and get a real vasectomy like the rest of us...


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## RocketTomato

Wangstang said:


> Anyone know whot to talk to about building some 6P drop in bulbs?
> 
> Wes



Checkout Nailbender in the Custom B/S/T forum


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## PhotonWrangler

It's not an LED, but I just stumbled across a UVC germicidal bulb at Target today. It's in the hardware section by the air purifiers. I bought one to experiment with.

Near as I can find out it's a 3 watt 10v bulb that's intended to work with a ballast in it's host device, a small UV air purifier that plugs into a light socket. The linked page shows a photo of the bulb also.

This lamp is very reminiscent of the old OZ-4 ozone bulb, aka the G-E G4S11, with an incandescent filament and a tiny drop of mercury visible inside the clear quartz envelope. They're commonly used in water purifiers and tootbrush sanitizers as well as air purifiers. Many years ago they used to use the OZ-4 bulbs in commercial restroom hand dryers.

At any rate I'm not sure what I'll use it for yet, but i'll think of something. :huh:


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## Rexlion

PhotonWrangler said:


> ...At any rate I'm nto sure what I'll use it for yet, but i'll think of something. :huh:


That sounds like a lot of us with our lights.


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## batmanacw

Marduke said:


> Why not just use the Steripen to begin with?



Steripens are a great way to get sick. They only work in water. If you dip your drinking vessel into the contaminated water source, then use the steripen, what is going to purify the germs you got on the outside and top of the container? You will just recontaminate trying to pour across the top of the container to put it into another container to drink it. 

The military tabs tell you to loosen the lid and shake the canteen to get antiseptic water onto the threads. The steripen purified water is not antiseptic so it would not kill anything by itself. The chemicals in the military tabs do actively kill bugs. 

Also, sterilized crap is still crap. The solids in the water actually will protect germs inside the solids. Light can't get to it so it lives through the treatment and goes into your belly. 

Use a real water filter.


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## travelinman

Rexlion said:


> I'm sorry, it just doesn't work that way. Stop shining that UV LED into your pants, and get a real vasectomy like the rest of us...


That's why I keep getting a real bad sunburn down there! :thinking:


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## travelinman

batmanacw said:


> Steripens are a great way to get sick. They only work in water. If you dip your drinking vessel into the contaminated water source, then use the steripen, what is going to purify the germs you got on the outside and top of the container? You will just recontaminate trying to pour across the top of the container to put it into another container to drink it.
> 
> The military tabs tell you to loosen the lid and shake the canteen to get antiseptic water onto the threads. The steripen purified water is not antiseptic so it would not kill anything by itself. The chemicals in the military tabs do actively kill bugs.
> 
> Also, sterilized crap is still crap. The solids in the water actually will protect germs inside the solids. Light can't get to it so it lives through the treatment and goes into your belly.
> 
> Use a real water filter.



I love my Steri pen, got two of them in fact. I used it all over S. America last year and didn't get the runs at all. I also didn't eat salads, or any fruits that I couldn't peel myself. You can also get bacteria from any food that you buy at a stand or restaurant so it's really hard to tell where you pick it up if you travel in any poorer part of the world. 

Steri pens work great though, if you are careful, but if you use the poison pills I wouldn't trust what the "poisons" do to you after they kill the bacteria.


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## batmanacw

travelinman said:


> I love my Steri pen, got two of them in fact. I used it all over S. America last year and didn't get the runs at all. I also didn't eat salads, or any fruits that I couldn't peel myself. You can also get bacteria from any food that you buy at a stand or restaurant so it's really hard to tell where you pick it up if you travel in any poorer part of the world.
> 
> Steri pens work great though, if you are careful, but if you use the poison pills I wouldn't trust what the "poisons" do to you after they kill the bacteria.


Did you use them in the field or just in a hotel? Too totally different situations. I would not hesitate to use one in my hotel room, but try dunking a glass in a river and not getting any bad stuff on the outside of the glass where you put your lips. 

I also tend to avoid eating anything not really well cooked when traveling in Mexico. That is when I can't avoid it totally. 

Those poisons taste terrible. that is why I use a katadyn hiker pro. The water from our local streams taste better than bottled after I am done. I am going to pick up a pocket filter by the same company in the near future. 

I travel for a living. A sweetwater filter, straw type filter, and micropur tablets come with me every time I travel anywhere.


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## turbodog

batmanacw said:


> Steripens are a great way to get sick. They only work in water. If you dip your drinking vessel into the contaminated water source, then use the steripen, what is going to purify the germs you got on the outside and top of the container? You will just recontaminate trying to pour across the top of the container to put it into another container to drink it.
> 
> The military tabs tell you to loosen the lid and shake the canteen to get antiseptic water onto the threads. The steripen purified water is not antiseptic so it would not kill anything by itself. The chemicals in the military tabs do actively kill bugs.
> 
> Also, sterilized crap is still crap. The solids in the water actually will protect germs inside the solids. Light can't get to it so it lives through the treatment and goes into your belly.
> 
> Use a real water filter.



Except filters do not get viruses....

I've got something nobody has mentioned, a uv aquastar
http://www.uvaquastar.com/skins/2008Style/standard2.aspx?elid=201&plk=69&SkipFlip=201

Fits to a normal 1l nalgene bottle. Had it for about 4 years now. Comes with a little set of prefilters (like a coffee filter) to screen out big chunks.


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## turbodog

For those reading this in a 'here's some good water filtering/etc advice':

Chemicals such as chlorine and iodine can leave a nasty taste. They also have a dwell (wait) time that can be short (in warm water) or 4 hours or more (in cold water). They also DO NOT GET cryptosporidium.

Filters can let viruses such as cryptosporidium through.

UV kills all nasty bugs if the water is clear enough. Keep the threads of the bottle clean and fitler out the chunky stuff and you'll be fine.

MSR makes a device which delivers some sort of mystery liquid (paraphrasing their words) based on salt water breakdown through electric current. It's supposedly effective against bacteria AND viruses. It suffers from dwell time, but taste is not affected much.

Boiling vigorously for 5-10 minutes kills everything.

Contaminants are somewhat removed by filtering as filters often contain charcoal 2nd stage filters which help with taste issues.

Personally, when in the backcountry, I filter then dose with UV. My msr filter screws on to top of the uv aquastar bottle. Filter comes off, uv goes in, and I am ready to go.

So that's it. Not going to derail thread anymore. Questions? PM me.


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## MountainVoyageur

It is now almost a year since the last post -- any update on when we might see SteriPEN products using UV LEDs?

:twothumbs


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## PhotonWrangler

I still don't see any major movement in the shortwave UV LED arena. I'd like to have an LED-based SteriPEN also, but there are apparently some serious manufacturing challenges. For now I'm sticking with conventional mercury-vapor UVC lamps.

**EDIT**

Maybe I should post this one under Pet Peeves, but I'm seeing some 365nm longwave UV*A* LEDs being marketed as "UVC" (shortwave germicidal) LEDs. Buyer beware. 

UVA = 400-320nm longwave "blacklight"
UVB = 320-290nm medium wave
UVC = 290-100nm "germicidal" shortwave


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## Wangstang

Another year down...any updates?

Wes


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## PhotonWrangler

I still haven't seen any breakthroughs in shortwave UV LEDs. We're still stuck with germicidal fluorescent lamps for awhile longer.


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## slebans

PhotonWrangler said:


> I still haven't seen any breakthroughs in shortwave UV LEDs. We're still stuck with germicidal fluorescent lamps for awhile longer.



I keep updating a folder whenever I come across anything to do with UV LEDs and disinfection. The latest entry I have is:
http://www.crystal-is.com/press.cfm/newsitem/86372

Some day, I want to have a LED based sterilization room for the daily disinfection of metal greenhouse production carts.

Stephen Lebans

Stephen Lebans


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## PhotonWrangler

Interesting - thanks Stephen.


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## slebans

Another "breakthrough" but still only half the WPE of the current non LED solutions.

http://www.s-et.com/news.html
[h=6]SETi reaches milestone UVC LED efficiencies of over 10%[/h]Sensor Electronic Technology, Inc (SETi) announced record efficiencies of ultraviolet light emitting diodes (UV LEDs) operating in the germicidal UV-C range of 11% external quantum efficiency (EQE) with a corresponding wall-plug efficiency (WPE) of 8%. This industry beating result was achieved under the DARPA Compact Mid-Ultraviolet Technology (CMUVT) program and in collaboration with Army Research Laboratories (ARL). read more (pdf)


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## PhotonWrangler

Another interesting find. Thanks Slebans.

Even with a WPE that is half of fluorescent-based counterparts, I think there will be a number of applications where this is the preferred solution just from the standpoint of ruggedness. I've never liked the idea of carrying around a fragile glass tube when I need a portable UV source.


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## eseemann

I know they work but I guess since I can not see the magic smoke I harbor some caveman type fear of it. Same with the water purification tablets. I would use them in a pinch but if I have time I think I will still boil. 
Thing the lights are really good for is going to some place like Mexico with a less then 100% water supply. Many an american has fallen before the might of the single cell.


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## Inkidu

The pdf link didn't work for me for the 278nm uv led so I thought I would post it again. 
Anyone know the usual length between a press release and the actual availability for this company.

Might be a DARPA hard problem. 

Any help would be appreciated.


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## slebans

Another breakthrough to keep an eye on.
http://www.hexatechinc.com/news_events.html#aug072012


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## slebans

http://www.ledinside.com/news/2013/1/japan_deep_ultraviolet_led_20120122

Japanese researchers Akinori Koukitu and Yoshinao Kumagai, who are professor and associate professor, respectively, at the Division of Applied Chemistry, the Tokyo University of Agriculture and Technology (TUAT), and researchers of Tokuyama Corp. , have made breakthroughs on a deep ultraviolet LED that has the world's highest levels of output characteristics.

With a forward current of 150mA, its output and external quantum efficiency are 20mW and 3.0%, respectively.


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## JohnR66

Nichia has some high power deep UV LEDs:
http://www.nichia.co.jp/en/about_nichia/2012/2012_122601.html


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## PhotonWrangler

JohnR66 said:


> Nichia has some high power deep UV LEDs:
> http://www.nichia.co.jp/en/about_nichia/2012/2012_122601.html



Wow. I'll bet those will cost a pretty penny.


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## The Electrician

I just found this forum with a search for UV flashlights. I'm interested in finding fluorescent minerals, some of which require short wave UV. In the past I've used a mercury lamp with a filter to pass the 254 nm radiation, but I've been wondering if LED technology has progressed to the point where a short wave (deep) UV LED flashlight would be possible for a reasonable price.

I see the Nichia LEDs linked a couple of posts up, and the power level is amazing, and more than needed for my purpose.

So far, I've been a little OT, but LEDs suitable for short wave mineralogy are also good for sterilization. Here's a link to a source of LED sterilization items I found. The radiant power of these LEDs is much lower than the Nichias, but the price is probably also lower. This is the US web site for a Chinese supplier:

http://www.ledwv.com/en/uv-sterilizer-c-21.html

It looks like you could actually buy these and not have to try to get a sample, although for the LEDs a minimum order quantity of 20 is required.


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## PhotonWrangler

Another fluorescent mineral collector here! Yes, the vast majority of them need a shortwave UV source to make them glow. My favorite is franklinite/willemite. I have a couple of small pieces of this and it looks just amazing under UVC.

Those shortwave UV leds look interesting. Maybe we can get a group buy together.


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## slebans

Single-chip UVC LED from Crystal IS Achieves 65mW cw at 260nm
http://www.ledinside.com/news/2013/3/uvc_led_crystal_is_20130325

“By employing die thinning and encapsulation techniques, we were able to increase the photon extraction efficiency to over 15%,” says founder & chief technology officer Leo Schowalter. Furthermore, improved thermal management and a high characteristic temperature resulted in low thermal roll-off up to 300mA injection current with output power of 67mW, an external quantum efficiency (EQE) of 4.9%, and a wall plug efficiency (WPE) of 2.5% for a single-chip UVC LED emitting at 271nm. “By fabricating our LEDs on our home-grown aluminium nitride substrates, we continue to set the pace of what is possible for the combination of highest efficiencies and longest lifetimes in the 250–280nm wavelength range, far surpassing diodes fabricated on sapphire,” Schowalter adds.


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## Mattaus

I looked into UV LEDs for water sterilization a few weeks ago and came to the conclusion that they were just too expensive ($260+ for a single LED!) for my purposes. If a group by can get that price down considerably I'd be very interested in a few...

- Matt


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## yumbrad

There have been some interesting results that show, for some bacteria at least, that the 365/385 nm region (which have cheap available LEDs) is sufficient to sterilize given sufficient power and time of exposure. Links:

http://link.springer.com/chapter/10.1007/978-3-540-36841-0_323#page-1
http://www.bioelectromagnetics.org/bems2010/supp_data/P-A-140.pdf

I'm gonna give it a try with a smattering of 361, 375, and 385 nm LEDs, since it's a fairly cheap experiment (and a lot easier to integrate into my little system than a fluorescent tube). I wonder if the efficacy of the 385nm is simply due to the FWHM bleeding down into the actual effective range...


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## slebans

yumbrad said:


> There have been some interesting results that show, for some bacteria at least, that the 365/385 nm region (which have cheap available LEDs) is sufficient to sterilize given sufficient power and time of exposure. Links:
> 
> http://link.springer.com/chapter/10.1007/978-3-540-36841-0_323#page-1
> http://www.bioelectromagnetics.org/bems2010/supp_data/P-A-140.pdf
> ...



Thanks for the interesting links. Makes you want to move that lamp containing a CFL bulb just a tad further away!
;-)


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## Mattaus

So with sufficient time 385nm UV-A LEDs can do the job. Given the low power of these ELDs (15mW I read in one paper) even at a typical Vf of 6V, you're talking about very little current which should allow a UV flashlight to last quite some time...I might do a bit more reading.


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## RetiredFireCaptain

I have been looking for UV-C leds to use in my vehicle's air conditioner. with the low power consumption and germicidal effects it would make for a healthier atmosphere in my car. I had a germicidal light installed in my home AC unit and it made a noticeable difference.


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## PhotonWrangler

RetiredFireCaptain said:


> I have been looking for UV-C leds to use in my vehicle's air conditioner. with the low power consumption and germicidal effects it would make for a healthier atmosphere in my car. I had a germicidal light installed in my home AC unit and it made a noticeable difference.



Interesting. Do you happen to know if the UVC lamp is of the newer, low-ozone envelope design? The newer ones have a surface treatment on the glass that allows germicidal wavelengths to pass through while blocking the primary ozone-producing wavelength of 185nm.


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## RetiredFireCaptain

PhotonWrangler said:


> Interesting. Do you happen to know if the UVC lamp is of the newer, low-ozone envelope design? The newer ones have a surface treatment on the glass that allows germicidal wavelengths to pass through while blocking the primary ozone-producing wavelength of 185nm.



TO be honest I do not know much about the ozone aspect of the LED's. There is so little info on UV LED's that I have had a difficult time learning. The one we had in our home was florescent and tied to the blower motor with a relay. It worked well and as proof before the light was in place the AC would kick in and you would get a wiff of mildew. After the light there was no smell of mildew. That is par for the course in South Florida.


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## slebans

PhotonWrangler said:


> Interesting. Do you happen to know if the UVC lamp is of the newer, low-ozone envelope design? The newer ones have a surface treatment on the glass that allows germicidal wavelengths to pass through while blocking the primary ozone-producing wavelength of 185nm.



For the past 6 years I have used UV in both my Water and Air handling equipment. I have not heard of this Ozone issue before today. Thanks for the heads up. Hopefully I can find compatible bulbs for the housings.


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## RetiredFireCaptain

So does anyone know of a reasonably priced LED in the UV -c range that is available for the general public to purchase? Especially one that is not so fragile? 
When I was a young paramedic working part time in the hospital, A maintenance man installed an 8' UV tube in the desk above the triage area. Two of my coworkers sat at the triage area for 12 hours when they finally realized what was going on. They were out sick for nearly a week with severe burns and I there was great concern about retinal burns. The light was in a desk partition that was less than three feet from them.


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## Anders Hoveland

I'm not sure how practical it would be, but frequency doubling optics are also a possibility. The frequency doubling optics in a green laser pointer has a relatively high efficiency of 25%. This could allow normal vissible frequency LED chips to be used, with the advantage of longer life, possibly even lower cost for higher power outputs.

Typically sterilization requires higher frequency UV (short wave), and I am not aware of any LED chips that can acheive sterilization frequencies.




Mattaus said:


> So with sufficient time 385nm UV-A LEDs can do the job.


I doubt it. It would certainly not be a reliable way to sterilize equipment. This wavelength is not much shorter than vissible violet light (405nm).
One could also say that "with sufficient time" _blue_ LEDs could be used to kill bacteria.
http://www.gizmag.com/blue-light-kills-bacteria/26026/


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## Lontong

so the conclusion is we are still waiting on 260 Nm cheap led


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## Mattaus

Pretty much. They do exist, but they are very expensive ($300+ each) and even then they won't sell direct to the public.

Sent from my Galaxy Nexus using Tapatalk 2


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## KDM

RetiredFireCaptain said:


> TO be honest I do not know much about the ozone aspect of the LED's. There is so little info on UV LED's that I have had a difficult time learning. The one we had in our home was florescent and tied to the blower motor with a relay. It worked well and as proof before the light was in place the AC would kick in and you would get a wiff of mildew. After the light there was no smell of mildew. That is par for the course in South Florida.



That smell is called the "Dirty sock syndrome". Heat activates the smell of mold/mildew spores. It also happens with heat pumps in the winter when the unit goes through a defrost cycle. The evaporator coil becomes damp during defrost because the unit is actually in cooling mode. Once defrost mode terminates and heat is applied to the coil it causes the odor. In your case the heat is building up in the off cycle. Once it cools back down no more smell. The UV light is killing the mold/mildew growing on the coil.


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## Anders Hoveland

I did find this:

Recent research has shown that commercially available UVA LEDs (365 nm) are already effective disinfection and sterilization devices.
(Mori, M.; Hamamoto, A.; Takahashi, A.; Nakano, M.; Wakikawa, N.; Tachibana, S.; Ikehara, T.; Nakaya, Y. et al. (2007). "Development of a new water sterilization device with a 365 nm UV-LED". _Medical & Biological Engineering & Computing_ *45* (12): 1237–1241.)

Still, I think shorter wavelengths are more effective at sterilization (and more damaging to human tissue oo: )


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## PhotonWrangler

Anders Hoveland said:


> I did find this:
> 
> Recent research has shown that commercially available UVA LEDs (365 nm) are already effective disinfection and sterilization devices.
> (Mori, M.; Hamamoto, A.; Takahashi, A.; Nakano, M.; Wakikawa, N.; Tachibana, S.; Ikehara, T.; Nakaya, Y. et al. (2007). "Development of a new water sterilization device with a 365 nm UV-LED". _Medical & Biological Engineering & Computing_ *45* (12): 1237–1241.)
> 
> Still, I think shorter wavelengths are more effective at sterilization (and more damaging to human tissue oo: )


 
I didn't think that longwave UV (365nm) was capable of breaking down molecular bonds like shortware UV can, but then I'm not a phd.


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## slebans

PhotonWrangler said:


> I didn't think that longwave UV (365nm) was capable of breaking down molecular bonds like shortware UV can, but then I'm not a phd.



The issue is one of time. In comparison to shorter UV wavelengths, the longer UV wavelengths take too much time to achieve similiar levels of disinfection. For the majority of air and water disinfection processes - there simply is not enough time to accomodate the longer UV wavelengths. 

I read up on this issue several months ago but I cannot remember if the longer UV wavelengths - even given sufficient time - can achieve the same levels of disinfection across all of the commonly targeted bacterial and viral organisms.


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## Anders Hoveland

PhotonWrangler said:


> I didn't think that longwave UV (365nm) was capable of breaking down molecular bonds like shortware UV can, but then I'm not a phd.


It is not, but there are _some_ bonds that 365nm can break apparently. Having a bit of chemistry background, once one gets into blue/violet regions of the visible spectrum, the light is energetic enough to start effecting some chemical changes, at least with some of the more sensitive chemicals, particularly pigment molecules. But you are right, 365nm is not energetic enough to directly damage DNA.


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## RetiredFireCaptain

BUMP! Anyone have a fresh insight on this thread?


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## PhotonWrangler

I just bought another CFL-style germicidal lamp. Wish I could've done this with LEDs but I still don't think the technology is ready.


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## lucca brassi

Problem with UV leds is that single cover very tight wavelength band , HID , fluorescent bulbs cover much wider band and thus much more effective 

some links with UV leds http://www.roithner-laser.at/led_deepuv.html or http://www.luminus.com/products/uv.html ( lambda depends on bin ) but price hurts ;-))


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## chillinn

lucca brassi said:


> Problem with UV leds is that single cover very tight wavelength band , HID , fluorescent bulbs cover much wider band and thus much more effective
> 
> some links with UV leds http://www.roithner-laser.at/led_deepuv.html or http://www.luminus.com/products/uv.html ( lambda depends on bin ) but price hurts ;-))



Actually came in to post that link, so seconded: http://www.roithner-laser.at/led_deepuv.html
but I don't see prices.

Wider band UVC is unncessary for sterilization. 254nm UVC is all that is necessary and the most effective frequency for germicidal irradiation: http://en.wikipedia.org/w/index.php?title=Ultraviolet_germicidal_irradiation . Mercury vapor just happens to emit 254nm so I suppose that is why the deep uv (not just black) flourescent lights are so reasonably priced (idk, I am assuming that's excited mercury vapor in those bulbs). 

Also, it is 185nm light that creates ozone (and not just "frequencies below 200nm," as many sources claim). And ozone itself is a better anti-bacterial agent than 254nm UVC, so often anti-bacterial water filtration systems include 254nm, but also 185nm in order to create ozone which is mixed with the water, which kills the bugs and promotes free radicals. Here's an example (and a surprisingly earnest and informative product page considering its commercial): http://www.waterth.com/products/uv_ozone/ozone_uvsterilizer.html

$4K (a price seen in another thread) is too much for a 254nm LED, but honestly, a couple hundred for the 254nm LED itself is pricey, but not out of the realm of possibility for purchase. I would save up and pay $350 for a 254nm solitare AAA powered LED keychain flashlight (especially if it was power led, and tough yet handsome), assuming these deep UV LEDs are going to take a while to come down in price. If anyone reading this can build these... why wouldn't you be doing this already? ... keep one or two in stock so it doesn't kill your economy, and sell for profit on CPFMarketplace? There seems to be more than enough interest from forum members already to make it a worthwhile endeavor. 

Now that I think about it, I'd prefer a keychain-sized AAA 254nm laser (with a 2nd visible targeting laser, say, 532nm), so I can sterilize a glass of water from across the room. I know I'm dreaming (I checked... twice... I am definitely asleep).


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## lucca brassi

> Actually came in to post that link, so seconded: http://www.roithner-laser.at/led_deepuv.html
> but I don't see prices.



on the top is pricelist/contact/order/...


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## PhotonWrangler

chillinn said:


> Now that I think about it, I'd prefer a keychain-sized AAA 254nm laser (with a 2nd visible targeting laser, say, 532nm), so I can sterilize a glass of water from across the room. I know I'm dreaming (I checked... twice... I am definitely asleep).



I hear ya. Unfortunately the glass will block the 254 wavelength completely. BTW if such a thing existed, I would want it for fluorescent mineral prospecting!


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## man123

I enquired from www.ledwd.com for UCV 260nm leds, below is there reply:




> we have no 265nm in stock for now, but 280nm is in stock.
> 
> 
> 
> 
> this performance is not stable, now it is replaced by SMD
> 
> 
> 
> it is much stable.but the price is the same.
> 
> 
> we think that 280nm is enough for medical application, you sure know that 265nm is much expensive than 280nm, so if 280nm is ok,you'd better choose 280nm. or if you are not sure, you can choose buy some 280nm sample for testing,once it is ok,and this will save much money.


seems 260nm production is not stable - will 280nm do the job? 

-any other vendors which vendor which is offering 260nm leds at below 5 dollar mark?

Regards,
Manish
www.openmeddev.net


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## RetiredFireCaptain

It has been a year since the last post to this thread. Has anyone learned anything now on the production and / or the availability of reasonably priced UV-c LED bulbs?


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## PhotonWrangler

I stumbled across a website that was supposedly selling UVC LEDs for reasonable prices, but something about the site looked a little sketchy so I held off on placing any orders. I still don't think these are ready for the masses yet.


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## SemiMan

-----


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## PhotonWrangler

Just saw this article today about a new material that emits UV light when activated by water. They didn't mention the wavelength. I wonder if this will be a viable source for solid state UV LEDs.


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## Linda Tan

phreeflow said:


> Hi All,
> 
> Thought I'd revisit the great folks here at CPF in hopes that you some of you geniuses (seriously) could help me answer this question.
> 
> I've seen people use Ultraviolet lights to sterilize various things such as water. So....I'm wondering if I could use UV Led's to accomplish the same thing.
> 
> What I'm confused about is what part of the Ultraviolet lights makes it able to sterilize things? Is it the wavelength, spectrum, frequency, color, etc, etc.
> 
> Please enlighten me!!
> Thanks all!!!


actually many wavelength have sterilize function.
general speaking, more near to 260nm have better effect of sterilize.
I know a company called Shenzhen Shining Future LED Technology Co., Ltd. have those kind of led.
you can ask datasheet from them.
I watched a video before, also introduced some types of sterilize led: https://www.youtube.com/watch?v=RL6bqWzRmLc


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## Linda Tan

agree, now some company already produce 260nm uv led


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## Linda Tan

<span style="color: rgb(51, 51, 51); background-color: rgb(239, 240, 248);">[video]www.sfleds.com[/video] now is available because of the mass production of led 265nm and led 275nm


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## Linda Tan

yes, 260nm uv leds have disinfect organics function.
you can buy it from Shenzhen Shining Future LED Technology Co., Ltd.
I don't think it's can be possible that paint/coat these LED's with something to get it to output only 260nm.....


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## phreeflow

Linda Tan said:


> actually many wavelength have sterilize function.
> general speaking, more near to 260nm have better effect of sterilize.
> I know a company called Shenzhen Shining Future LED Technology Co., Ltd. have those kind of led.
> you can ask datasheet from them.
> I watched a video before, also introduced some types of sterilize led: https://www.youtube.com/watch?v=RL6bqWzRmLc



Wow, I posted this question 2 years ago so I am surprised to hear a response. It is amazing how much technology has advanced in the world of LED. I will have to study everyone's responses as I am still interested in this UV Led. Thanks all and let's keep the discussion going!


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## BayMoe

Bump. Any news?


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## night.hoodie

Alaric Darconville said:


> 254nm UV has (in the UVC range) is particularly effective in sterilization, because it breaks up the DNA in microorganisms. It has a quantum energy of 4.9 electron volts per photon.
> 
> 254nm LED's are somewhat rare, though, and usually mercury vapor lamps are used to make germicidal lamps.



After reading subsequent posts and seeing inexplicable mention of 260nm, I thought it would be beneficial to quote Alaric Darconville's early post, because this is the best reply so far. Though 260nm is very close to 254nm, it is not precisely accurate to say 260nm is best at germicide. Certainly, any light peaking at 260nm will have a lot of light output at 254nm, thus making it acceptable for germicidal applications, but why introduce 260nm at all? Perhaps it is due to different LED output usually being speced in multiples of 5, so a 250nm LED probably exists, a 255nm LED probably exists, and a 260nm LED probably exists, but I doubt there is any 254nm LED. Perhaps one day... but maybe there is little point being that accurate, or maybe producing something so precisely rated is difficult.

Mercury vapor lamps are particularly compelling for use in germicidal applications because they emit ultraviolet light with two peaks in the UV-C band at 253.7nm and 185nm due to the mercury within the lamp. 254nm is the absolute most effective frequency for germicidal applications. 185nm is probably the second most effective frequency. The lamp spectrum has other peaks, but these two are the most effective against germs. No wavelength adjustment is necessary to the output of a mercury vapor lamp, because it is nailing in tight bands the two most effective germicidal UV-C frequencies. What a happy accident of physics that mercury behaves this way.

Though LED can be made to output a narrow band of UV-C, one of the issues with LED UV-C is that as the LED heats up, the peak wavelength will drift, and in the case of germicidal applications, frequency drift will reduce the germicidal effectiveness. This is a reason why very good and stable UV-C LEDs are still rare and outrageously expensive, because to guarantee the stability of the wavelength at a certain frequency the manufacturer/developer must take prodigious effort to build in high quality heat sinking with expensive materials, and the production yield is probably not high when it is necessary or best to have the peak wavelength as close as possible to a particular target, such as 254nm.

I wanted to also mention that many consumer 5mm LED UV-A flashlights, such as those most popularly found peaking at frequencies of 375nm or the like, can be effective at germicide. I expect even the more modern powerLED at these frequencies may also be effective, but somewhat less than 5mm LED because, presumably, powerLED is more power efficient, and probably has a narrower frequency band than 5mm LED. This is because, even though the light _peaks_ at it's rated frequency, the spectral curve is often very wide, and there is probably some output even below 100nm. These flashlights, such as the Arc UV AAA, especially when slightly overdriven with NiZn or L91 (which may serve to shift the frequency higher), can exhibit germicidal properties, and will also cause ozone to form due to the spectral curve dipping below 100nm where oxygen absorbs those UV-C high frequencies and forms ozone, and ozone itself is germicidal. These 5mm LEDs are of course not nearly efficient as the more expensive powerLEDs, especially the ones rated in narrow bands close to 254nm, but, anecdotally speaking, they can kill germs and sterilize surfaces directly in the path of the light. More exposure and greater intensity is always more effective.


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## PhotonWrangler

Well said night hoodie. 

Many of the older mercury vapor lamps emitted significant energy at 185nm, and that wavelength is responsible for producing ozone, which is a toxin at ground level. The newer lamps have a specially formulated envelope that blocks most of the 185nm energy while passing the more useful 254nm light.


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## FRITZHID

unless you specifically find yourself an O3 lamp. you can find them in Ozone generators for hvac systems. one major issue of any UV-B/C/Ozone in any electronics devices is that UV and Ozone both degrade plastics and Ozone is a strong oxidizer that can cause some corrosion problems.


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## PhotonWrangler

FRITZHID said:


> ...and Ozone is a strong oxidizer that can cause some corrosion problems.



...which is why it's bad for your lungs also.


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## FRITZHID

PhotonWrangler said:


> ...which is why it's bad for your lungs also.



and eyes, nose, throat, sinuses, etc! lol


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## Ken_McE

360 nm LED:

http://www.thefoxgroupinc.com/products/by-wavelength/360-nm/


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## Connor

Voilà, 150mW *2*65nm LEDs: http://nict.jp/press/2017/04/04-1.html


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## PhotonWrangler

Wow. Thanks, Connor.

I can't determine from the article whether these are available yet, and for what price. I'll bet they will be expensive.


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## Connor

I have no clue, I just learned about those 10 minutes ago. They're brand-new apparently.


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## light-modder

I saw a portable UV sterilizer on kickstarter or indigogo a little bit ago. Aimed at parents of babies for sterilization of bottles but mentioned that lots of other things could be done as well. I wish I could remember the name. They also said they were using some new technology and I think they had a patent or one pending. Anyway, looked kinda cool.


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## Alaric Darconville

night.hoodie said:


> After reading subsequent posts and seeing inexplicable mention of 260nm, I thought it would be beneficial to quote Alaric Darconville's early post, because this is the best reply so far.


And then you CRUSHED it with yours.


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## HarryN

Just an FYI, I met with S-ET last week and the price and lifetime of good quality, reasonably high output UV LEDs has advanced remarkably.

http://s-et.com/http://s-et.com/

I am going to buy a couple and let my summer intern experiment with them.


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## woodpeck

UV LED for sterilization, I just learned something new. My sister sometimes uses my UV flashlight to cure her gel polish.


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## PhotonWrangler

Woodpeck, I would not trust your UV flashlight for sterilization. You need shortwave UVC for this, in the neighborhood of 265nm. Virtually all UV flashlights operate in the longwave region of 365-400nm. Longwave UV can't break down the cell walls in the germs. While there are some new shortwave UV LEDs out there, I haven't seen any of them show up in flashlights yet.

Wikipedia has a good article on UV germicidal wavelengths. Look at the graphs on the right and you'll see that anything longer than ~310 nm is virtually useless for germicidal use (normal blacklight is 365-400nm).


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## RetiredFireCaptain

Another couple of years gone and still no information on germicidal LED's.


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## alpg88

now a days those G lights are installed in every top of the line water coolers, and prbly not only top of the line, same with some commercial AC units. if you need a disinfecting light, just look for spare bulbs for those. they are otherwise regular fluorescent lights, regular ballast will work with such lights, most of the time.


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## PhotonWrangler

alpg88 said:


> now a days those G lights are installed in every top of the line water coolers, and prbly not only top of the line, same with some commercial AC units. if you need a disinfecting light, just look for spare bulbs for those. they are otherwise regular fluorescent lights, regular ballast will work with such lights, most of the time.



This is correct. The germicidal versions of fluorescent tubes are made of a special type of quartz envelope with no phosphor coating. They otherwise act like regular fluorescent tubes. There are handheld wand sterilizers that use miniature fluorescent germicidal tubes. They also make germicidal CFL bulbs with the built-in ballast and regular edison base. Just be careful around them; they're VERY bad for your eyes and skin.


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## runcyclexcski

I just posted on 300 nm 30 mW LEDs, coindicentally. They are not cheap. I use them to cross-link and destroy DNA nanostructures. It takes 1 hr of irradiation to chop 90% of DNA into non-detectable pieces. But, I imagine, to sterlize you would not need that degree of DNA 'digestion'. You would need to experiment with the dosage. Cheers!


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## PhotonWrangler

runcyclexcski said:


> I just posted on 300 nm 30 mW LEDs, coindicentally. They are not cheap. I use them to cross-link and destroy DNA nanostructures. It takes 1 hr of irradiation to chop 90% of DNA into non-detectable pieces. But, I imagine, to sterlize you would not need that degree of DNA 'digestion'. You would need to experiment with the dosage. Cheers!



What do these 300nm LEDs cost?


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