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We can rebuild him. We have the budget... but do we have the technology?

In the process of reviewing the proposed enhancements for the Six Billion Dollar Man the following was discovered:

Enhancement: Extended Voluntary Apnea
Purpose: Implanted device significantly extends the period which the subject may hold their breath while maintaining peak physical activity.
Proposed Mechanism: Excess oxygen is extracted from the blood and stored inside this device during periods of rest. When a decrease in blood oxygenation is detected, this device can fully oxygenate and remove CO2 to maintain subject operation. Collected CO2 is released and oxygen reserves are restored during next period of rest.
Duration: Unknown.
Recovery Time: Unknown.
Feasibility: Unknown.

Please help fill in the blanks.

Can such a device be constructed, assuming 2050's technology? (Exponential increase in technological levels can be assumed.)

If the device takes the volume of half of one lung, what kind of duration can be expected during full exertion? How long to fill the stores and expel the waste?

Samuel
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  • What's your energy budget? What's your cooling budget? – Mark Oct 22 '15 at 00:25
  • There's some non-technological precidence for this in the form of skin divers, who may work, underwater, for 10 minutes or more on a single breath. – Cort Ammon Oct 22 '15 at 00:41
  • @Mark Let's assume energy per dozen uses is stored in a ultra-high density energy storage device about 10% the size of the while device. It's charged inductively at some other time. That is, don't worry about it :) – Samuel Oct 22 '15 at 01:02
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    You might be interested in this paper: http://www.researchgate.net/publication/1738233_In_Outer_Space_without_a_Space_Suit by Alexander Bolonkin. While he comes off as something of a mad scientist, the numbers seem reasonable, and the project does seem feasible (for some values of feasible anyway....) – Thucydides Oct 22 '15 at 15:45

2 Answers2

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Actually, you'd be better off not building an oxygen storage unit, but to build a reversible glucose-oxygen fuel cell. This would have the advantage that when it was doing its thing, not only would oxygen be supplied and $\text{CO}_2$ removed, but glucose would also be supplied, making the recipient almost completely self-sufficient as long as its power supply held out.

If we have $$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \to 6\text{CO}_2 + 6\text{H}_2\text{O},\quad\Delta G = −2880 \text{ kJ per mol of } \text{C}_6\text{H}_{12}\text{O}_6$$ then by reversing this and applying energy, we can turn carbon dioxide and water back into glucose and oxygen, using power stored in the converter implant or supplied externally via whatever means (induction?)

If we go by current trends in battery technology, battery capacity doubles each 22 years. From 2015 to 2050 is 35 years, so we'd expect 235/22 = 3 times the capacity in our best batteries. Current Li-ion batteries are 460kJ/kg or 827kJ/L, so we'd expect 1380kJ/kg or 2481kJ/L.

Given that the volume specified is 'half a lung', the total volume of the lungs is about 6.16l in an average human: (Total Lung Capacity + Physiologic Dead Volume), so half of one of two lungs would be about 1.54L.

Considering that our battery/fuel cell might have 0.04L of ancillary equipment and be 2/3 energy storage by volume, we'd have 1L of battery, capable of storing 2481kJ.

If we take a highly active 18-30 year old, 90 kg male, from charts on this page, we can see that the daily energy requirement is up to 18.8 MJ/day.

This means that 2.418MJ divided by 18.8MJ/day = 0.129 day, or 3 hours. By reducing energy consumption with total inactivity, this could conceivably be stretched out to six hours.

Recovery time would basically be the recharge time for the battery - it could be charged by using the glucose-oxygen fuel cell, or by external induction. There would be some waste heat, but the human body is very good at dealing with waste heat. It might recharge in as little as a quarter hour on external power, up to an hour if relying on glucose and oxygen.

It is not inconceivable that a reversible glucose/oxygen fuel cell could be invented by 2050, though it would be pretty bleeding-edge technology.

Samuel
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Monty Wild
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  • Your three hours is way too long--in most situations where this would be needed he's going to be quite active. Your hourly use will be well above 18.8MJ/day/24. Otherwise, I agree, this gives the most support time. – Loren Pechtel Dec 20 '16 at 23:48
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I've thought about exactly that for a "mermaid" kind of power. How much oxygen does a human use? We need about 600 grams of oxygen per day, which is surprisingly little! Now storing that in a light and compact manner is the issue.

I looked up state of the art systems one time. There's some new stuff that absorbs oxygen remarkably well. But a quick check on Google:

the Vika system uses a canister containing about 1 liter (2.4 kg) of perchlorate to generate 600 liters (0.86 kg) of oxygen, enough for one person for one day

That's pretty good in the bulk department. What future developments might bring is being able to release it without too much waste heat, and in-situ recharging.

My rough idea uses a tube-shaped artificial organ in the abdomen that's about 1 liter in volume but shaped like coils so it's spread out to fit well. It plumbs the blood through and can release oxygen and absorb carbon dioxide, with a capacity of 1/3 of a day. But it takes a long time to recharge and has a limited number of cycles.

Meanwhile, a device replacing one lobe of the lung (that's 1/5, not half) allows for a much smaller capacity but rapid recovery when breathing. I figure 20 minute capacity under moderate exertion. Recovery speed is that it takes all the oxygen from 1/5 of the inhailed air. Exercise speeds recharging because you breathe more!

JDługosz
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