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Thread: UV LED's for sterilization???

  1. #1

    Default UV LED's for sterilization???

    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!!!

  2. #2
    Flashaholic* Alaric Darconville's Avatar
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    Default Re: UV LED's for sterilization???

    Quote Originally Posted by phreeflow View Post
    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.

  3. #3

    Default Re: UV LED's for sterilization???

    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.

  4. #4

    Default Re: UV LED's for sterilization???

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

  5. #5
    Flashaholic* MattK's Avatar
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    Default Re: UV LED's for sterilization???

    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.

  6. #6
    Flashaholic* JohnR66's Avatar
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    Default Re: UV LED's for sterilization???

    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.

  7. #7

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by MattK View Post
    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.

  8. #8

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by JohnR66 View Post
    If you want to tinker [...]: Protect your eyes.
    Don't ignore this piece of advice from John!

  9. #9
    Moderator Kestrel's Avatar
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    Default Re: UV LED's for sterilization???

    Quote Originally Posted by phreeflow View Post
    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.

  10. #10
    Flashaholic* MattK's Avatar
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    Default Re: UV LED's for sterilization???

    LOL

    X=X=X=X

  11. #11

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by Kestrel View Post
    My deepest and sincerest apologies, but I just couldn't resist:

    Yes.
    Yeah, yeah...whateva...I never said I knew anything about this stuff. I'm a NOOB . 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...

  12. #12
    Flashaholic cdosrun's Avatar
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    Default Re: UV LED's for sterilization???

    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

  13. #13

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by cdosrun View Post
    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

  14. #14

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by drmaxx View Post
    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!

  15. #15
    Flashaholic* MattK's Avatar
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    Default Re: UV LED's for sterilization???

    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.

  16. #16
    Flashaholic jerry i h's Avatar
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    Default Re: UV LED's for sterilization???

    +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 even if it were of the correct wavelength.
    Last edited by jerry i h; 11-12-2008 at 06:11 PM.

  17. #17

    Default Re: UV LED's for sterilization???

    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!
    Last edited by phreeflow; 11-12-2008 at 06:02 PM. Reason: typo

  18. #18
    *Flashaholic* Marduke's Avatar
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    Default Re: UV LED's for sterilization???

    Why not just use the Steripen to begin with?

  19. #19
    Flashaholic* MattK's Avatar
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    Default Re: UV LED's for sterilization???

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

  20. #20
    *Flashaholic* Marduke's Avatar
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    Default Re: UV LED's for sterilization???

    Quote Originally Posted by MattK View Post
    Yes. As their official battery supplier I am 100% in agreement.
    +1 for a totally non-biased opinion....

  21. #21

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by phreeflow View Post
    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.

  22. #22

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by phreeflow View Post


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

  23. #23

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by drmaxx View Post
    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.

    Quote Originally Posted by dbvanhorn View Post
    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.
    Last edited by phreeflow; 11-13-2008 at 11:17 AM.

  24. #24
    Flashaholic gillestugan's Avatar
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    Default Re: UV LED's for sterilization???

    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.

  25. #25

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by gillestugan View Post
    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.

  26. #26

    Default Re: UV LED's for sterilization???

    Quote Originally Posted by gillestugan View Post
    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.

  27. #27
    Enlightened
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    Default Re: UV LED's for sterilization???

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

    Wes

  28. #28
    Flashaholic* 1 what's Avatar
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    Default Re: UV LED's for sterilization???

    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.

  29. #29
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    Default Re: UV LED's for sterilization???

    Quote Originally Posted by 1 what View Post
    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).
    So many lights, so little money (cause I spent it on lights). I'm not afraid of the dark, the dark is afraid of ME!

  30. #30
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    Grinser2 Re: UV LED's for sterilization???

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

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

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