After reading the extra-long post about some potential reliability issues with SteriPENs, just wondering if a portable device that uses an LED in the correct UV-C frequency might be in the works. My limited research indicates that such an LED would be expensive, however, it would seem to have advantages of durability, longevity, power efficiency, etc. Anyone know if someone is actively working on something like this? Thanks for any info in advance...

Edited by FarmHand357 on 03/01/2012 21:20:02 MST.

I know the Classics have lots of problems associated with sensor failure, but I used an Adventurer Opti on the whole A.T last year and loved it. Still use it and its going strong. Wouldn't trust any other model out there though from my experiences seeing about 8 of the Classic models die within 500 miles of use.

LED UV

Have heard a little of that around here. The technology is not quite there for backcountry use. Costs primarily.

It will come out 2 weeks after you buy something else.

Yes, I think the technology is not there yet. The wavelength would have to be in the 250-260nm range, which is shorter than most commercial UVB LEDs. Those that do emit at these wavelengths have very low power (less than one milliwatt), and cost several hundred dollars apiece. The power of these LEDs will have to increase a thousandfold, and the cost will have to drop a hundredfold, before an LED Steripen is possible.

This is something I have discussed with Steripen over the years. What is needed is a UV-C LED radiating at 254 nm. So far, we (the science community) can make LEDs in the UV-B range at about 350 nm (from memory). Progress to a shorter wavelength is slow as it is hard to make the required semiconductor material. 254 nm corresponds to a huge band-gap, and we don't actually have any obvious candidates.

Would a 254 nm LED be better than the Philips germicidal discharge tube used at present? (That also radiates at 254 nm.) It would be hugely better! I was going to say 'infinitely better', but I couldn't quite manage that. :-) The power consumption would drop massively.

We don't try to use UV-B photons for two reasons. The simple one is that the UV-B photons do not as much energy as is found in the UV-C photons, and you need a lot of energy to damage the DNA connections. The more complex reason, and the major one, is that we actually need photons at ~254 nm in order to break certain bonds in the DNA. If the photon has an energy significantly different from that, the bonds don't respond. It's a resonance thing.

It will happen, just not this year.

Cheers

What happened with the mÜV micro-UV water purifier?

Roger, as a point of trivia, there are UVC leds, as I noted in my post above. Thorlabs and several other companies sell LEDs having emission peaks as low as 240nm.

Also, we use 254nm radiation for pathogen control because it happens to be a mercury vapor emission peak, not because that particular wavelength is ideal for germicidal applications. Pyrimidine dimerization (major germicidal mechanism) occurs more efficiently closer to 260nm, and 260nm LEDs are not hard to find.

They just cost too much and their power is too low.

Edited by ckrusor on 03/02/2012 09:42:10 MST.

The mUV is back and can be purchased directly from Meridian Designs for $49.

They've changed it - it no longer has the magnetic leads (which I, quite honestly, really liked). It now comes with a USB charging cable that retracts - you can see it on the website.

I've had one of their prototypes of the new mUV since last summer and really like it. I purchased a small solar battery that has a USB output and an internal lithium ion battery. I get 8-9 purification cycles per charge with my unit but I know they were working on improving that - which delayed the release of the mUV.

Now that it's available for purchase again I'll do a review and post it in the reviews section.

Hi Colin

The field of UV LEDs is advancing - slowly. Yes, one can buy the LED245W from Thorlabs, but it gives only 70 microwatts and costs $444, or the LED260W, 300 microwatts and $310. Somehow, I don't think either would provide enough power for realistic use in the field, and the cost would be ... ultra. Thanks for the update.

I take the point that 260 nm is better than 245 nm, although there is actually a broad band between 240 and 280 which is usable if there is enough power.

> They just cost too much and their power is too low.
Exactly. Sadly.

Cheers

Much appreciation to all; great info here. Will be looking for an mUV review and how it compares to SteriPEN. Thanks again...