Just wanted to share test results of this face mask I made for exercising in the cold weather. It's based on a device called "LungPlus" which I integrated with a 3M respirator using 3D printed parts. The LungPlus is a mouthpiece with an aluminium heat exchanger inside which captures the temperature and the humidity of the air during exhalation, and then warms the air during inhalation.
The inhaled air did feel surprisingly warm even during intense exercise, which is consistent with a 2019 paper shown below (that paper showed warming to +20C at subzero temperatures, and today was +1C). Previously, I wore a scarf or a P2 face mask while exercising in the cold; both restricted breathing and did not warm the air as efficiently as the current mask.
This does not replace inhalers, pills and biologicals, of course -- I still take all of these.
The idea is not new -- I based it on a 1992 paper by a Liverpool lung doctor (linked below). The LungPlus device works by itself but one has to hold it in the mouth at all times which I find uncomofortable, b.c. one cannot breathe through the nose and cannot speak. So I took two LungPluces and connected them to a face mask, and it worked quite well together -- as long as you do not care about the way you look.
Turns out, there is another device like this on the market, I linked it further down.
Maybe look into that Swedish device, might be less trouble making it work. I only found out about it while writing my post :). They claim the Swedish nordic team uses their masks.
I used to do my own 3D printing, and, like you said, the fumes were horrific, even though I built an extractor fume hood for it. In addition, the printed parts had a smell, too, and made my hands itchy simply by touching them! That was Makerbot ABS, but as we all know it's not real ABS, there is more going on with that plastic.
Thus, I started outsourcing 3D prints to Shapeways (now in the NL). Their prints are very cheap and precise. I can also count on their printing to work every time -- with my own 3D printing, there was always trial and error, and the parts would fail and delaminate, whereas SW's look more "isotropic". Also, their plastic does not smell (I have a very sensitive nose), and does not shed particles (tested with a laser particle counter). Ironically, the LungPlus devices had a smell (the manufacturer assured me it was a medical grade plastic). So I placed them next to my HEPA filter intake for a few days for continous air movement, and that helped.
I now need to combine the mask with my powered respirator to get clean air, together with the warmth. The "snout" on the mask will get even more glorious, but I do not care
When I need truly "asthma friendly" prints I order Shapeways's aluminium -- that stuff is solid metal, but costs 5-10x more than Nylon. Ironically their "Stainless steel" smells like sulphur -- bad news for asthma, avoid. Bronse is OK.
I am waiting for the summer before I print in TPU so I can vent out the window. I mainly use PETG which would not work for a flexi mask at all. I use my printer mainly to make toys and gadgets for the granddaughter and Fishing bits and bobs for myself and old school friends of over 50 years. Keep up the good work maybe you will come up with a better design over time.
Shapeways also prints in a flexible material they call "silicone", but I would not dare use it for anything medical. The 3M mask I used has an internal plastic "skeleton" to which the adapters are bolted with M2 bolts. It would be nice to make my own silicone parts; I've tried it, and it's not trivial (molds etc) and involves nasty chemistry. Better leave it to the professionals. The best way I found so far is to take existing good-quality mask and to bolt things to it.
For the 3D printer fumes, one can make an acrylic box (or a plywood box with an acrylic window) with a hole at the top, connect it to a 75-100 mm diam flexible duct, and direct the duct into the cooking stove exhaust via an axial blower. Or, one can vent into a hole in the window (that would require making a special window which is a project on its own).
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