[Covid-2/Covid-19] DIY Low Dose Oxygen and Air Filtration Device

If you have a loved one suffering respiratory distress, here is a simple oxygen therapy device that you can put together in a day using material commonly found at home and your local pharmacy. This system should deliver between 0.23 to 0.3 inspired oxygen partial pressure. Please see the precautions at the end of these instructions before use.

Supplies

1 Small air purifier

1 Flexible yet sturdy sheet of plastic (This will be used to form a duct over the air purifier vent. I cut dimensions 20% larger than the vent out of a portfolio cover)

4 Empty plastic bottles (1L each, wash thoroughly)

6 Assorted balloons (3 punch balloons, 2 modelling balloons, 1 standard party balloon roughly 30cm )

2+ Bottles of 3% hydrogen peroxide (1L each)

2+ Pkgs of yeast (active dry packets recommended)

Adhesive tape (Non-porous, such that it does not permit airflow), scissors and a sharp tool or knife.

Step 1: Airflow Duct

Cut the plastic into a best fit polygon about 20% larger than the shape of the purified air vent.

Crease the polygon to create a raised structure housing the vent with sufficient headroom for airflow.

Cut both ends of a punch balloon, maximizing for inlet and outlet diameter.

Cut a hole slightly larger than punch balloon inlet diameter into the polygon; either where it will face the topmost part of the vent or at the topmost part of the polygon folded perpendicular to the vent. If necessary, cut the bottom part of a bottle to use as an open ended cylindrical stabilizer through the hole, and stretch the punch balloon over it, leaving room at the punch balloon outlet for connection to another cylinder.

With the punch balloon through or over the hole (or both, depending on what is best for your shape), stretch and fold the balloon inlet as flat as possible over the perimeter of the hole. Tape the inlet such that the connection is airtight.

Make sure the edges of the polygon are clean so that they lay flush and tape it around the purified air vent, ensuring that the tape does not bubble or fold. If necessary fortify the non-porous tape with any other kind of adhesive tape.

Switch on the air purifier to verify that an airtight duct was formed, then unplug the air purifier.

Step 2: Tubing

Cut off the top quarter of bottle 1 to use its mouth as a port template.

Cut the longest possible cylinder from the same bottle (leaving off the bottom part) to use as tube 1.

Use the port template to trace the bottle mouth onto tube 1 at half tube 1 cylindrical length, then, using the trace, cut a hole into tube 1 to create an oxygen port.

Cut off the top quarter of bottle 2 to use as tube 3.

Cut the longest possible cylinder from the same bottle (leaving off the bottom part) to use as tube 2.

Cut both ends of the other two punch balloon, maximizing for length with large enough inlet and outlet diameter to fit over the cylinders when stretched, and use them to connect tube 1 to tube 2, and tube 2 to tube 3 as shown in the image.

Connect tube 1 to the duct outlet from Step I with the oxygen port facing down.

Step 3: Oxygen Source Tank

Inflate then deflate the standard party balloon to pre-stretch it to be used as a catalase compartment.

Fillet the mouth of the balloon as shown in the image in order to be able to stretch it over the catalase port defined in the next step.

Cut a small rectangle near the top of bottle 3 to create a catalase port, sized such that you are able to comfortably pour in liquid, yet small enough to be able to stretch the balloon mouth over it.

Place the balloon through the catalase port, then stretch and tape its mouth over the edges flat around the port, such that the connection is as water-tight as possible.

Wrap a modelling balloon around the mouth of bottle 3 starting just beneath the first ring as shown in the image by winding the balloon such that its wound diameter at the bottom is greater than the tightly wound top that should have wound up approximately flush with the first ring.

Apply marginal force to connect the mouth of the oxygen source tank to the oxygen port (be careful not to crack tube 1, you may have to file the oxygen port to widen the port a bit, using a file if necessary) such that the modelling balloon wound around the mouth of the oxygen source tank immobilizes the airtight connection.

Power up the air purifier to verify that relatively airtight tubing, ports and connections provide gentle airflow out of tube 3, then unplug the air purifier.

Step 4: Oxygen Terminal

As the tubing should now hang with support from the oxygen source tank, place bottle 4 vertically against the mouth of tube 3 and use the mouth of tube 3 to trace a circle on the side of bottle 4.

Using the trace, cut a hole into bottle 4 to create a terminal port.

Wrap a modelling balloon around the mouth of tube 3, in a fashion similar to the modelling balloon wrapped around the mouth of the oxygen source tank (created from bottle 3).

Connect the mouth of tube 3 to the terminal port.

Optionally, add a mask to the oxygen terminal using a modelling balloon at the mouth of bottle 4 to prevent airleak.

Step 5: Operation

Mix one pkg of yeast in a 1/4 cup of water.

Carefully disconnect the oxygen source tank from the oxygen port.

Using a sharp tool or a knife, poke a small hole into the bottom of the catalase compartment balloon. Pour the minimum of mixture from the cup into the compartment sufficient to test for drip from the catalase compartment into the oxygen source tank. Repeat, expanding the hole until the yeast mixture in the catalase compartment drips at a rate of approximately one drop every few seconds.

Empty and rinse the oxygen source tank, then fill with less than 1L of 3% hydrogen peroxide until there is a space of few centimeters between the bottom of the catalase compartment balloon and the hydrogen peroxide.

Connect the oxygen source tank back to the oxygen port, then power up the air purifier.

Fill the catalase compartment halfway up with yeast mixture. The reaction should cause oxygen bubbles to rise within the solution. Immediately note the time.

Expend the oxygen source tank hydrogen peroxide and sufficient yeast mixture to determine when effervescence ceases, jiggling the oxygen source tank slightly to verify and note the time difference.

If necessary, estimate modification of the drip rate such that the reaction lasts no less than an hour and no more than four hours. Empty the tank and expand the hole in the catalase compartment balloon accordingly.

[demonstration video included after the next section]

Step 6: Precautions

Excess oxygen intake may cause hyperoxia, a condition that may lead to oxygen toxicity and even death. The parameters in these instructions were calculated to result in a low dose of supplemental oxygen. Increasing the hydrogen peroxide concentration to extend the duration of oxygen delivery or increasing the reaction rate by any means requires recalibration of parameters and may be dangerous.

Prior to use, your diligence is due on at least the following topics: breathing gas, the advantages and disadvantages of low dose supplemental oxygen and purified air, oxygen toxicity, fraction of inspired oxygen, and the decomposition of hydrogen peroxide.

This system was built by the author using dry active yeast and one liter bottles of hydrogen peroxide. The author self tested the device by intermittently breathing through a mask connected to the mouth of the oxygen terminal throughout nonadjacent ten minute intervals and did not experience negative effects. While risk of irritation may be low, hydrogen peroxide fumes are a known irritant. Consider placing a perforated balloon containing a catalase damped loose napkin upon the tank/tube mouth prior to its connection to the relative port, or other filtration methods.

Please note that the oxygen released by this device is not medical grade. Keep the tanks and tubing clean with inhalation safe materials. Use at your own risk.

Step 7: Demonstration

Upon completion of this experiment, dry yeast and hydrogen peroxide were no longer locally available. Self grown yeast and what little hydrogen peroxide was left were used to create the video demo (hence a murky, viscous catalase)