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Implausible and overfunded CPAP machine on Indiegogo

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Re: Implausible and overfunded CPAP machine on Indiegogo

#61

Post by dragonwriter »

amluto wrote: post #56
Alkim wrote: post #52

Earlier quoted context omitted.

Well now I guess I have to do the math: W = P(b)V(b) ln(P(a)/P(b)) ( https://en.wikipedia.org/wiki/Compressed_air_energy_storage ) CPAP requires roughly 10 cm of water pressure = 0.01 Bar Sea level atmospheric pressure is roughly 1 bar So the device has to pressurize to 1.01 Bar Now I’ve looked it up, and a typical CPAP machine moves 20 to 60 liters per minute Let’s say 30 liters per minute = 1800 liters per hour W =…

Where does that 30 liters per minute go? I'm reasonably sure it's not going into the user's nose or mouth. Part of the claimed innovation here is that the thing sticks directly into the user's nose. If it seals well, it's plausible that there's very little wasted air, which would account for the factor of roughly five. (Also, you used the formula for isothermal compression, I think. A tiny little device like they sho…

> Part of the claimed innovation here is that the thing sticks directly into the user's nose.

Putting the whole machine in the nose is novel, but I don't see how that is innovative in terms of changing required functionality compared to nose-only masks, which are already a thing.

Re: Implausible and overfunded CPAP machine on Indiegogo

#62

Post by Alkim »

userbinator wrote: post #19

The question I’m asking here is what should we do as engineers? Talk about it and spread the word to others that this is impossible to do. There's also some interesting discussion here, mostly to the tune of "it won't work": http://www.eevblog.com/forum/crowd-funded-projects/the-airin...

Thank you for pointing that out. It was interesting reading.

I was hoping that someone in this community would know someone in indegogo responsible enough to say wait a minute, this is not plausible. I took a look at indegogo's terms of service and found only this:

"If the Campaign is claiming to do the impossible or it's just plain phony, don't post it. "

Which is pretty weak.

But I suppose the old saw that 'a fool and his money are soon parted' still applies in the crowdfunding world...

And here's a -real- battery powered CPAP machine, taking a laptop-type lithium ion battery:

http://www.cpap.com/productpage/Hoffman-Laboratories-Breathe...

Re: Implausible and overfunded CPAP machine on Indiegogo

#63

Post by Smushman »

Background on Airing, LLC, located in Burlington, MA.

I looked up Stephen A. Marsh (see http://www.fundairing.com/ under 'inventor').

Interesting guy - a strange history. He also is CEO of Encite LLC (also located in Burlington, MA). He does have many patents in fuel cells, etc.

Previous to Encite LLC he was CEO of a now-defunct technology startup Integrated Fuel Cell Technologies, Inc. (IFCTI)

Encite LLC was formed from IFCTI, through some obtuse legal machinations.

http://www.potteranderson.com/delawarecase-185.html

I am no expert in law, but it sounds like he basically ran IFCTI into the ground as CEO, then bought it and its resources back at a large discount via Encite LLC. The previous board members tried to sue him but lost due to some ambiguities in the laws.

Maybe someone else has more?

BTW having used a CPAP I know it is not possible to generate the volume and pressure (particularly the pressure) needed by something this size without a quantum leap in current technology.

I can't devise a method to prove and explain my conclusion. Perhaps someone more versed in the area can.

Re: Implausible and overfunded CPAP machine on Indiegogo

#64

Post by TylerE »

TylerE wrote: post #60
mcphage wrote: post #57

Earlier quoted context omitted.

> Mine will pay for a new mask (~$150) every 3 months, and a new machine every year (~$1k). Wow... that's some great insurance! I've got decent insurance, but mine will only cover 80% of costs, on a mask every 6 months, and a machine every 5 years.

Gold level Blue Cross plan via Obamacare. So yea, while not the absolute best it's pretty good.

Edit: Actually, I was wrong. Machine only every 5 years. They do cover masks/tubing every 3 months though.

Re: Implausible and overfunded CPAP machine on Indiegogo

#65

Post by amluto »

dragonwriter wrote: post #61
amluto wrote: post #56

Earlier quoted context omitted.

Where does that 30 liters per minute go? I'm reasonably sure it's not going into the user's nose or mouth. Part of the claimed innovation here is that the thing sticks directly into the user's nose. If it seals well, it's plausible that there's very little wasted air, which would account for the factor of roughly five. (Also, you used the formula for isothermal compression, I think. A tiny little device like they sho…

> Part of the claimed innovation here is that the thing sticks directly into the user's nose. Putting the whole machine in the nose is novel, but I don't see how that is innovative in terms of changing required functionality compared to nose-only masks, which are already a thing.

It shouldn't have anything to do with the required technology. It might allow a considerable reduction in leakage, though.

Re: Implausible and overfunded CPAP machine on Indiegogo

#66

Post by amluto »

TylerE wrote: post #54
amluto wrote: post #47

Earlier quoted context omitted.

I know basically nothing about how CPAP devices work, but why does it need to move so much air? There are snorkels on the market with little check valves so your exhaled air goes out a different pipe than your inhaled air. They cost maybe $20. I can't imagine that a super-expensive CPAP machine doesn't have a similar pair of valves.

Basically, because you're sleeping, and even a good mask seal will leak a fair bit, and there is also a lot of intentional leakage around the valves because you don't want stale air hanging around, or condensation building up, and you have to make sure that the person can breathe sort-of normally if the power fails or something like that.

As a guess: with a plugged-in device, the manufacturer doesn't care about power consumption, and the thing already needs to be be able to supply enough air for the peak flow while you're inhaling, so it doesn't really matter if it leaks.

If they cared about power consumption, they could presumably make it less leaky and use check valves to prevent issues with stale air or inability to breathe if the fan stops working.

I've used snorkels with separate in and out tubes and check valves to route the air correctly. It solves stale air problems (which are irrelevant for snorkling because the total air volume is much less than the amount of air you breathe in per breath) and causes serious suckage (because you really want your exhaled air to displace water that comes in the intake, and check valves prevent that), but for CPAP it might make sense.

Re: Implausible and overfunded CPAP machine on Indiegogo

#67

Post by gooseyard »

I believe the Airing thing is expected to use these things:

http://www.murata-ps.com/emena/2012-05-22.html

I was also skeptical of the Airing claim, although after reading about the Murata piezo blower things, they're amazing, whether Airing is able to make a CPAP out of them or not.

Frankly, as an old, fat, CPAP using guy, I'd rather eat mouldy cheese than use a nasal pillow CPAP device. Plus, the Airing thing would have to be strapped to my face anyway; at my Rx pressure it'd blow out of my nose within an hour. The hose on my traditional BiPap turbine machine doesn't bother me at all.

I'd be delighted to have a smaller BiPap machine made out of these Murata things, if it meant a less bulky power supply and a smaller base unit.

Re: Implausible and overfunded CPAP machine on Indiegogo

#68

Post by mcphage »

TylerE wrote: post #64
TylerE wrote: post #60

Earlier quoted context omitted.

Gold level Blue Cross plan via Obamacare. So yea, while not the absolute best it's pretty good.

Edit: Actually, I was wrong. Machine only every 5 years. They do cover masks/tubing every 3 months though.

Oh, phew. Still, 100% coverage, and faster masks is better than mine.

Re: Implausible and overfunded CPAP machine on Indiegogo

#69

Post by semiazas »

Call Indiegogo to task. They're developing a reputation for shady practices. Considering they get their cut whether the startup is real or not begs the question are they honestly diligent in vetting a project? Given their history it seems to me they're more interested in their piece of the pie and believe those foolish enough to buy in get what they deserve. You won't see them refunding their portion of a fund when it becomes apparent it was a scam. They carefully pretend nothing bad happened and go on down the road to the bank.

Re: Implausible and overfunded CPAP machine on Indiegogo

#70

Post by Smushman »

gooseyard wrote: post #67

I believe the Airing thing is expected to use these things: http://www.murata-ps.com/emena/2012-05-22.html I was also skeptical of the Airing claim, although after reading about the Murata piezo blower things, they're amazing, whether Airing is able to make a CPAP out of them or not. Frankly, as an old, fat, CPAP using guy, I'd rather eat mouldy cheese than use a nasal pillow CPAP device. Plus, the Airing thing would…

That was a really impressive find!

Armed with this, I took interest in your response and checked out the math.

Interestingly, this device seems to produce the pressure!

Using their specifications of the piezoelectric pump on the page you sent.

Piezoelectric pump produces 1.5kPa. This converts to 15.3 cm WC (centimeters of water column) or cmH2O. 4-20 cmH2O is the range of a cpap!!

But, the airflow needed at that pressure is a critical issue as long as you want to breathe freely. The piezoelectric pump produces 0.8 liters per minute.

At http://www.sleepdex.org/cpap.htm it says a cpap produces 20 to 60 liters of air per minute (lpm).

To reach the lowest end you need 20 lpm. Calculate 20 / .8 = 25

So you need 25 of these piezoelectric pumps to reach the lowest possible; 75 of them to reach the high end. This is literally almost an order of magnitude.

And in case you thought so; piezoelectrics can't scale. They are very limited in size, by the physics of the vibrations.

So still not even close. It would require a quantum leap in technology over what we have available.

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