Are you working with UV-C LEDs for Disinfection? If so, tell me about it.

Hi Randall,

A friend of mine is using UV-C for disinfecting shoes. When the family comes in from outside, they leave their shoes underneath the LEDs, i.e. the shoes remain in a storage area that disinfects them, outside a secondary door of the home. I thought it was a great idea!

I honestly would never have thought of that for removing odors, I presume. 

Yes, I think so, and also any viruses/bacteria that may be around. Possibly it also slightly helps when kids forget to wash hands when they get to school for mealtimes etc., less chance they will have bacteria from their shoes onto their hands. But probably they will have picked up loads of bacteria from elsewhere by that time.

Many years ago when I thought I wanted to be a microbiologist, I grew large quantities of Clostridium bacteria as part of my research during an NSF internship.  We used UV lamps for disinfecting our workstations.  I can attest to their effectivity in killing test cultures .

I've looked at building something with UV-C LEDs recently because of Covid, but never got around to researching parts.  I'll be interested in seeing what type of components you select.

I did get a portable UV disinfection unit as Christmas gift, but I'll admit to not having tested its effectivity.

I was involved in building the water purification systems for the Sudbury Neutrino Observatory, which used UV as one aspect in the complex process of making the cleanest water in the world. This was a pretty big water purification plant, which used food grade polyethylene pipes. When the room lights were turned off you could see all the polyethylene pipes glowing blue - acting like light pipes from the UV sources. Since then I've been interested in using UV to make water safe to drink. There are some countries where it is ill advised to drink the water. I thought about re-purposing the UV sources in those old EPROM erasers, but have not yet launched a development, partly because of safety concerns - UV can cause cataracts not to mention skin cancer. I also thought about using it on the common problem of smelly hockey equipment. Unfortunately UV also degrades many synthetics and the last thing you want is for your protective materials to fail to do their job. The advent of UV LEDs opens up some applications, but it takes significant and complex research, for example, to figure out what dosage would be needed to achieve some specific "germ-free" drinking water target. I would suggest anyone wanting to experiment with UV to take precautions not to expose people to UV. If it wasn't for potential human exposure, it might be more useful for insect control. (I believe it is already used for insect control, but I am too leery of it to try it out)

You could imagine an invisible curtain of UV that would prevent any harmful or contagious biologicals from passing through alive, but care would need to be taken to ensure the light didn't reflect onto a human. It might allow better interaction with immune-compromised individuals or contagious individuals.

A UV lamp is a key component of our pond filter and it comes with a lot of warnings.

Yes - my PhD was all about using UV-C LEDs for water disinfection. Right now, I'm involved in a part-time project in collaboration between several universities to try and bring this technology to developing countries for point-of-use water disinfection using only photovoltaic power.

- Gough

Our R&D team at BiBEAT LTD developed a UVC room sterilizer for medical use under the supervision of our mentor Prof. Siddique-e Rabbani few months ago. This can be used in Operation Theater or ICU room to disinfect surroundings after the Operation is over, or a patient left the ICU. The aim is to reduce the HAI [Hospital / Healthcare Associated Infections]. We achieved great results while collaborating with a renowned hospital to test the device. We have used 254nm germicidal lamps of in total 180W in different configurations.

Room size: 13ft x 10ft x 8.5ft (approx)
Microorganisms painted at 5 different points

After 30 minutes of exposure, all samples had more than 8 log reduction in concentration.

However, during the design considerations we found that there was divergence of light beams out of a UVC tube lamp. The two corners of the tube lamp have dark zones where essentially no or little light reaches from the tube lamp directly. This forced us to change our initial design to increase the number of tubes in different angels to achieve optimum result in every direction. LED gives a better uniform light beam than lamp, I hope. Also it will be much more efficient in terms of energy and wavelength. But definitely that increases the cost.

Another advantage will be - tube lamps are fragile. LEDs have higher longevity and will be easier to handle or replace. The intensity of the exposure can be optimized according to the room size or necessity. Which is not easy in case of tube lamps.