Personal Corona Defense Air Purifier

After two serious (important) Instructables about how you can reduce the risk of infection for yourself and your loved ones, and the rest of the world with the help of common sense, as well as science and technology,....

....here finally an Instructable for fun, that you should take with a pinch of salt.

Not that the science and the technology in this project wouldn’t work as described - no magic was employed!

Walking around in public might lead to some strange questions as well as possibly, some attention, that you might not want.

Anyway,….

With the first Lockdown over here in Germany at the end of March 2020, my wife and kids were ordered to stay home, while I was to go to the office as usual, because we provided essential IT services.

On that weekend, I was just a little bit worried about spending days in the crowded office, with closed windows and some colleagues constantly and loudly on the phone and an airborne virus rampant….

So, that Saturday, while my wife was sewing face-masks for us, I thought about how to actively clear the air of possible viral particles - using „normal“ house-hold items, of course!

How to stop/destroy viral particles?:

1. thick filter
2. filter treated with salt
3. filter treated with Silver (water disinfectant)
4. Air Ionizer
5. UVC disinfection
6. Hydation of bio particles with salt-free H2O (distilled water)

Implementation:

As with the thick fleece 3rd layer filter for our home-made masks, I decided on the use of the 5mm thick molton fleece as a primary filter, because the turbulence in the air passage through it makes adhesion of particles due to collision with the fibers more probable. The material is simply the padding from an ironing board.

Since the Corona virus has a lipid shell, it is also more probable to adhere to the chemically „organic“ material.

The filter was treated with a salt brine, because the salt forms tiny crystals on the fibers, that cause further turbulence, as well as increasing the total surface area of the filter.

Bacteria, as well as viral particles can be destroyed by contact with salt due to the dehydrating effect.

To disinfect organically contaminated water, Silver compounds are often added. In order to employ this effect, the filters were also sprayed with a Silver solution.

Any particles passing the physical filters need to be destroyed. The primary way to achieve this, is by ionizing the air with a simple Car Air Purifier, that, as a practical bonus, also packs a small fan and can be run on 5V. The one I had lying around also has a couple of additional USB-Ports to charge a phone or other device.

As another level for the air purification, I decided on a small chip with three UVC LEDs that I had found on Alibaba a couple of weeks before. The power for it could also be handily provided by the Fan unit.

As a final measure I decided to re-humidify the purified air with distilled water, which can destroy remaining organic particles, due to hydrostatic shock.

The rest was simply empty soda bottles and a few other bits and pieces from the strange cardboard box beneath my desk in the basement.

The following links are not the original items I used, but pretty much identical, or with the same function as the ones I used at the time.

It seems, that it’s actually a slightly expensive project, if you want to buy the components and don’t just repurpose the ones you have lying around.

- 2x Rubber bands

- Physical filter - ironing board padding (10€):

https://www.amazon.de/Leifheit-Bügeltisch-Polsteru...

- NaCl Salt from the kitchen

- Silver spray (4€):

https://www.aldi-sued.de/de/p.vitalia-masken-hygie...

- Mini Car Air Purifier (36€):

https://www.amazon.de/Luftreiniger-tragbarer-Ionis...

- UVC LED Board (9€):

https://www.aliexpress.com/item/4000495419542.html...

- Humidifier (7€):

https://www.pearl.de/a-NC4955-3033.shtml;jsessioni...

- Distilled water old spray bottle

- USB cables

- Power bank 20000mAh (30€):

https://www.anker.com/de/products/variant/powercor...

- Any face-mask you have

- 4x 0,5 l empty Soda Bottles, or so….

The chip with the UVC LEDs, I previously used for another little project.

I had wanted to do a quick disinfection gadget for face-masks consisting of a small bucket, that could hold just one mask. <so look at the pics and build it, if you wish....

The disinfection cabinet I described in a previous Instructable simply proved easier to use and more effective.

The Filters:

Cut tree pieces of molton padding to fit onto the air intakes of the Car Air Purifier. In my case, they measure about 5x3 cm.

Take a couple of spoon full NaCl (salt) and dissolve them in a few milliliters of clean water. It’s good if the solution is really saturated, because, once you spray the solution onto the filter pieces, using an old spray bottle, they dry quickly and you get lots of micro-crystals on the fibers of the filter.

Spray the filter pieces with the Silver-solution and let dry.

Attach the filters across the air intakes of the Car Air Purifier using the two rubber bands. Make sure, the USB ports are still accessible.

The UVC-Irradiation-Chamber

As a next step you want to transfer the ionized air through a UVC treatment to the re-hydration stage.

The simplest way in this case was cutting off the top 3rd of a 0,5 l soda bottle. The lower edge needed to be enlarged a bit with a couple of vertical cuts and made to fit using a short length of clear tape.

The chip with the UVC LEDs was placed into this „Funnel“, the wires „dangling outside. The LED driver board is connected via a USB cable to one of the ports on the Air Purifier.

To transfer the irradiated air to the next chamber, a short piece of hose is attached to the mouth of the bottle, using a hose-clamp and some clear tape. the other end of the hose is connected to the thread of a bottle cap, held in place and sealed by further clear tape.

The Re-hydration-Chamber

Well, what is easier, than just to take another of your favorite Soda bottles.

To continuously provide distilled water that is placed inside the bottle to the humidifier, a strip of the filter material is placed into a short length of pvc-hose as a wick. the hose is previously cut, so that it barely fits into the bottle, with light pressure against the lid to ensure the wick always stays in contact with the bottle lid = the humidifier.

A ca. 1 cm hole is drilled into a bottle cap to provide access for the wick to the humidifier.

The humidifier is glued to the holed bottle cap with the help of some hot glue. This also seals the bottle to accidental spills during mobile use.

After closing the bottle, the air-flow needs to be further channelled to the user.

This is achieved with the use of another bottle, here only the lower third is removed.

A hole the size of the bottle threads is cut into the side of the new cap, low enough, so that the air coming from the previous chamber enters below the humidifier, so that it will produce more turbulence in the chamber. The neck of another bottle is pushed from the inside through the hole, using the thread of another „decapitated“ bottle caps as an inside seal.

The hose from the UVC chamber is simply „screwed on“, thus sealing the apparatus.

A length of window foam insulation strip is used as sealant between the water bottle and the new lid-cap.

Since the Water bottle is too short, the remaining lower 3rd from the last cut up bottle bottle used for the re-hydration chamber is used as new base to extend the length.

The USB cable from the humidifier is connected to the second USB port un the Air Purifier.

Air Hose Connection

To provide a stable and easily removable connection port, to attach an air-hose to the previous chamber, a hole of about 1,5 cm was drilled through another bottle cap. The piston chamber of a liquid soap pump was pushed in from the inside, through the holed cap, its thin seal ring used as seal for the assembly.

The air hose is pushed on this „funnel“, the connection further stabilized by a short piece of PVC hose and some hot glue. Some more clear Tape is used to close up the small hole in the side of the soap pump piston.

A - In the configuration without an air hose attached, tied together by a couple of strips of velcro, the Air purification system can be run in a „stationary“ mode by setting it on a desk and connecting the Air Purifier to a 5 V power supply. This way the system can purify the air in the near vicinity around a person sitting at a desk.

B - By screwing on the air hose and attaching the system to a power-bank, the system can be made into a „portable“ mode. In this mode, the hose is inserted under the face-mask from the side by one cheek, or from below, by the chin.

The air-flow is just strong enough that the intake of air through the face-mask is greatly reduced when taking a deep breath. This is especially useful with self-made masks of unknown filter capacity.

Said, and done took about one day. The work was finished by Sunday afternoon, shortly before I got the mail that all personell were ordered into home-office!

So, the whole system was assembled and the functionality tried and tested.

But sadly, I could never take it into the field, or the office for that matter.

It certainly would have caused lots of strange gazes, shaken heads and confused colleagues.

And that strange UVC-glow is simply so cool! (REMEMBER: UVC radiation is dangerous!)

With the UVC radiation employed, I would have had to add some shielding inside the chamber (aluminum foil) to make it safe for normal use.

But without it, the assembly looks much cooler!

So, I hope you liked this only half-serious Instructable - I certainly had fun figuring everything out and putting it together on such short notice.

PS: Maybe next time I'll do it in Steam Punk.... ;-)

Greetings from Heidelberg, Germany,

stay safe and healthy,

Nils

And ALWAYS stay fascinated!