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A working pair of lungs


eamon

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Hi all

 

I have been tasked with helping an artist with an exhibition.

 

The exhibit is a model of the human torso complete with working lungs... It is the working lungs where I come in.

 

I am looking at a pump or some form of automated bellows and I am a bit stumped as to how to proceed.

 

I have yet to see the unit (later today).

 

Has anyone achieved this before? I am thinking a small pump with a pressure switch to simulate breathing as one possibility.

 

The solution will need to run for approx 6-9 months!

 

Cheers in advance.

 

Eamon

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Rather than reinventing the wheel, have you thought about looking at an actual ventilator? A quick search for “medical ventilators” on eBay yields a few suitable devices for sensible prices.

 

These ventilators should give you a reliable solution with all the necessary control surfaces to reproduce a realistic effect. If you go down this route you probably want to avoid using anything that needs compressed gas to work. Non-invasive type ventilators meant for home use are probably the most suitable.

 

The effect you are trying to achieve is regularly done in medical simulation for training purposes so should be reasonably straight forward to put together. Your local anaesthetic department may well have a stash of outdated kit/historical ventilators that you could borrow and cobble together.

 

There’s lots of information online about how these ventilators are designed if you particularly want to build a bespoke unit.

 

If you need any advice regarding setting any of this up feel free to make contact, I’m training as an anaesthetist at the moment. So making lungs go up and down is a bit of a special interest...

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Our 1988 solution to making a 'handless body in a bath of blood' breathe was a bit OTT but made out of available scrap.A rubber tyred wheel from a baby buggy about 3" diameter mounted on a motorbike engine which was driven by a 1/2" shaft, this had a pully about 6" diameter with a drive belt from the shaft of a 1440 RPM washing machine motor.this gave a reduction of about 72:1. A hose connected to the spark plug hole inflated and evacuated a wheelbarrow inner tube in a cavity in the chest of the manikin.It ran at about 20 breaths per minute.

A cam on the middle shaft pushed against a Hillman Imp accelerator piston to pump the blood from the severed wrist joints.

It was very Heath Robinson but it ran 15 hours a day for a bit over a week leading up to Halloween without any failures.

 

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No experience in this but I would possibly consider using a liquid to fill the lungs rather than air / gas, what you're wanting to create is essentially a sealed hydraulic system and liquids are less compressible than gases. This would give a more efficient system, and would be less prone to effects due to heating of the fluid. Depends on how it would look on the actual model though - liquids may not work for this application.

 

Liquids would also show any leaks a lot quicker too!

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Right let's go back to basics here. The average rate of breathing is between 12 and 20 times a minute. Assuming that the exhibition is open for eight hours a day over nine months this means that the mechanism used will have to operate say 20x60x8x273 times. I make that 2,620,800 operations. That to me takes one to the reliability limits of what can be put together out of bits and pieces that one might have to hand. On those groundsMatt's notion of using a ventilator seems an attractive one.
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I helped a guy make an art piece that was a heart beating in time to an audio track - then dying

He went with a speaker for his needs but assuming that you stick with fluid, he made a clay model, plaster mold, then used silicone rubber for the heart.His was too thick on the first attempt but the mood allowed a few more versions and eventually he got a robust heart that would beat.

 

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No experience in this but I would possibly consider using a liquid to fill the lungs rather than air / gas, what you're wanting to create is essentially a sealed hydraulic system and liquids are less compressible than gases. This would give a more efficient system, and would be less prone to effects due to heating of the fluid. Depends on how it would look on the actual model though - liquids may not work for this application.

 

Liquids would also show any leaks a lot quicker too!

That's a good point, especially as there will not be that much fluid in the event of a leak.

 

Possibly make it red to look like blood, just in case.

 

 

I helped a guy make an art piece that was a heart beating in time to an audio track - then dying

He went with a speaker for his needs but assuming that you stick with fluid, he made a clay model, plaster mold, then used silicone rubber for the heart.His was too thick on the first attempt but the mood allowed a few more versions and eventually he got a robust heart that would beat.

 

Our beating heart for the same Halloween event came from a joke shop with a rubber bulb but it was far too flimsy to do 1/2 million cycles and we opted for mechanical. initially we tried a loudspeaker as we used a sound effect too but found it difficult to make the mechanical connexion and settled on a modified washing machine water valve solenoid.

 

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Hi all

 

Sorry for the slow & late reply. The work thing sometimes takes over our lives...

 

I have to spin many plates in my new job.

 

I am veering towards the ventilator idea. Seems practical and I have a large college medical dept at my disposal. A friend of mine also suggested it as an option and with discussion, seems like the best idea to trial.

 

Plus it is more likely to give the desired effect, I hope....

 

 

 

 

Thanks again for the advice.

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Hi all

 

Sorry for the slow & late reply. The work thing sometimes takes over our lives...

 

I have to spin many plates in my new job.

 

I am veering towards the ventilator idea. Seems practical and I have a large college medical dept at my disposal. A friend of mine also suggested it as an option and with discussion, seems like the best idea to trial.

 

Plus it is more likely to give the desired effect, I hope....

 

 

 

 

Thanks again for the advice.

That's good.Let us know how it goes.

 

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