Hi Ronald & all,
As our insights in this problem grow, I now think:
-a reliable mechanical pump design is 20% of the solution
-PEEP-valves, overpressure valves,tubing, 3-way valves and filters are relatively simple parts, but not necessary easy to source. If you can find a way to massively source those outside of medical suppliers, that is 15%
-the software and sensors is 65% of the value. The more I discuss this, the larger this number gets.
In essence: if you accurately monitor & control your pressures, volumes, RR, IE and oxygen content & you have a clear interface with visual feedback, you have functionality – no matter what the air source is.
Our sensors are going to end up to be plastic parts (3D-printed) , with mass-produced electronics. That is 100g of hardware that fits in a shoe box and can be mailed off. Add a laptop for the graphs and control (dump the physical buttons)
I was discussing the italian diving-mask solution (the Decathlon snorkel mask) with Manu Malbrain today, he is in favor of this as he sees a lot of advantages in a solution where he can filter the return air, establish PEEP & high oxygen content, but can avoid or postpone all the complications / nasty side effects of intubating patients.
Our pump would not work with that, not enough Minute Volume for the higher flow needed as you breathe out into the freshly added air mixture, but there is no reason our software with good sensors cannot control a turbine that can deliver the required 60L/min of oxygen/air mixture.
There is also no reason this same control software could not be adapted to fit a proportional valve on a pressurized air/oxygen source.
Please let me know if my view is wrong. This is a project where me and my whole team are learning on-the-go, there was no time for a literature study, so we are potentially making stupid choices.
Here is a link to a demo-video from yesterday.
Don’t get too enthusiastic, that Prototype 5 was cursed and died of electrical problems after two nights of useless work-around attempts.
Turns out windscreen wiper motors have their ground on the casing. If you reverse the motor (which you don’t do in a car) you put 12V on the frame of the motor. We knew that, we thought we could ignore that for now.
If you do a plexi machine, you are just fine, it’s low voltage. If you build an aluminium version, well…
We think fondly of Prototypes 1 to 4. We will not speak of 5 again.
6 & 7 have rubber feet on the motor mounts and a plastic piece in the pull rod.
Also, Audi is coming tomorrow to help with a 10-man team.
SKF did overnight shipping on Sunday, after some of their people spent a day disinfecting 2000 ball-bearings, then re-greasing them. We think we asked for 100 for the first 20 Beta-models, but I am not sure at this point.
best, Lieven
