5 ms·

Tiny nuclear hearts is the future

aetherspawn 5y ago
I have a feeling there isn’t enough power in nuclear at the scale that would fit inside the body with sufficient shielding. Nuclear is surely for low power devices, but human hearts would actually use a great deal of power (estimate 50-100W). It won’t last for years like you’d expect. Even if you _can_ package it, still needs batteries for redundancy and clearly those don’t fit inside either. Patients with batteries carry around massive backpacks. Brings a new meaning to ‘having a meltdown’ though. Overheating nuclear heart would literally boil your blood.
- Someone 5y ago
  On https://hypertextbook.com/facts/2003/IradaMuslumova.shtml https://hypertextbook.com/facts/2003/IradaMuslumova.shtml, the highest estimate there is 5W, and that’s an outlier on that page. That may be because of the difference between output power and input power needed to produce it. One citation there says the mechanical efficiency of the heart is about 20%.
  - aetherspawn 5y ago
    It’s pretty easy to calculate if we knew how long the battery lasts. We can estimate the size of the battery from the weight of the backpack (6kg) and use the time to flat to estimate the power draw - that’s the actual electrical energy usage of the heart.
  - iancmceachern 5y ago
    Exactly, the human heart is a marvel of design and performance. Typically these devices use between 10-30 watts of power for each side of the heart (in the LVAD case). For an artificial heart (which is two LVADs, basically a LVAD and a RVAD) it's more like 30-60 watts of continuous power. The human heart is amazing.
- marcan_42 5y ago
  A heart uses nowhere near 100W of power. That's about the overall power consumption of the entire human body at rest.
  - aetherspawn 5y ago
    My estimation was based on a value that is a fraction of the smallest brushless automotive water pump that I work with, which is smaller than a heart and barely suits a go kart.
alod 5y ago
They implanted plutonium powered pacemakers in the 1970s. Unfortunately we moved away from the Jetson's future.
- iancmceachern 5y ago
  Last I read there were a few folks with them still implanted to this day. It's interesting, one of the major development challenges for these devices was making them safe so that if the patient were to be cremated they didn't create a small dirty bomb.
bserge 5y ago
With enough radioactive fuel, it will last for the rest of your life!
iancmceachern 5y ago
This is where they started. The story I was told was that president Lyndon Johnson was having heart trouble. Coming right out of the Apollo age, the powers that be said "we can send a person to the moon, why can't we build an artificial heart". They thought it would be a relatively simple problem to solve. At that time the battery technology wasn't there, so the only way to make something work was nuclear power. They came up with an implanted sterling engine, powered by a nuclear thermopile with the cold side of the heat flow being the human body. In that case, the limiting factor for how much power could be generated was how much heat could we dump into the human body without causing things like internal burns and necrosis. They actually built several prototypes, tested them in animals, but never in humans. These devices were enormous, they typically had a large thermopile/sterling engine portion connected by a shaft or hydraulic connection to the pumping portion of the device. Both needed to be implanted in the body, and the devices were entirely mechanical, no electronics needed. The thermopile drove the sterling cycle engine, which then either acted on hydraulic working fluid to actuate the blood pump, or used a shaft or similar to actuate the blood pump from the sterling engine. a few links: https://physicstoday.scitation.org/doi/full/10.1063/PT.3.3168 https://physicstoday.scitation.org/doi/full/10.1063/PT.3.316... https://ota.fas.org/reports/8232.pdf https://ota.fas.org/reports/8232.pdf https://www.nytimes.com/1972/03/21/archives/nuclear-heart-pump-moon-shot-for-medicine-nuclearpowered-heart-pump.html https://www.nytimes.com/1972/03/21/archives/nuclear-heart-pu... https://www.theatlantic.com/technology/archive/2013/03/the-true-story-of-the-government-programs-that-tried-to-build-an-atomic-heart/274266/ https://www.theatlantic.com/technology/archive/2013/03/the-t...

I have a feeling there isn’t enough power in nuclear at the scale that would fit inside the body with sufficient shielding. Nuclear is surely for low power devices, but human hearts would actually use a great deal of power (estimate 50-100W). It won’t last for years like you’d expect. Even if you _can_ package it, still needs batteries for redundancy and clearly those don’t fit inside either. Patients with batteries carry around massive backpacks. Brings a new meaning to ‘having a meltdown’ though. Overheating nuclear heart would literally boil your blood.

Someone 5y ago
On https://hypertextbook.com/facts/2003/IradaMuslumova.shtml https://hypertextbook.com/facts/2003/IradaMuslumova.shtml, the highest estimate there is 5W, and that’s an outlier on that page. That may be because of the difference between output power and input power needed to produce it. One citation there says the mechanical efficiency of the heart is about 20%.
- aetherspawn 5y ago
  It’s pretty easy to calculate if we knew how long the battery lasts. We can estimate the size of the battery from the weight of the backpack (6kg) and use the time to flat to estimate the power draw - that’s the actual electrical energy usage of the heart.
- iancmceachern 5y ago
  Exactly, the human heart is a marvel of design and performance. Typically these devices use between 10-30 watts of power for each side of the heart (in the LVAD case). For an artificial heart (which is two LVADs, basically a LVAD and a RVAD) it's more like 30-60 watts of continuous power. The human heart is amazing.
marcan_42 5y ago
A heart uses nowhere near 100W of power. That's about the overall power consumption of the entire human body at rest.
- aetherspawn 5y ago
  My estimation was based on a value that is a fraction of the smallest brushless automotive water pump that I work with, which is smaller than a heart and barely suits a go kart.

alod 5y ago

They implanted plutonium powered pacemakers in the 1970s. Unfortunately we moved away from the Jetson's future.

iancmceachern 5y ago
Last I read there were a few folks with them still implanted to this day. It's interesting, one of the major development challenges for these devices was making them safe so that if the patient were to be cremated they didn't create a small dirty bomb.

bserge 5y ago

With enough radioactive fuel, it will last for the rest of your life!

iancmceachern 5y ago

This is where they started. The story I was told was that president Lyndon Johnson was having heart trouble. Coming right out of the Apollo age, the powers that be said "we can send a person to the moon, why can't we build an artificial heart". They thought it would be a relatively simple problem to solve. At that time the battery technology wasn't there, so the only way to make something work was nuclear power. They came up with an implanted sterling engine, powered by a nuclear thermopile with the cold side of the heat flow being the human body. In that case, the limiting factor for how much power could be generated was how much heat could we dump into the human body without causing things like internal burns and necrosis. They actually built several prototypes, tested them in animals, but never in humans. These devices were enormous, they typically had a large thermopile/sterling engine portion connected by a shaft or hydraulic connection to the pumping portion of the device. Both needed to be implanted in the body, and the devices were entirely mechanical, no electronics needed. The thermopile drove the sterling cycle engine, which then either acted on hydraulic working fluid to actuate the blood pump, or used a shaft or similar to actuate the blood pump from the sterling engine. a few links: https://physicstoday.scitation.org/doi/full/10.1063/PT.3.3168 https://physicstoday.scitation.org/doi/full/10.1063/PT.3.316... https://ota.fas.org/reports/8232.pdf https://ota.fas.org/reports/8232.pdf https://www.nytimes.com/1972/03/21/archives/nuclear-heart-pump-moon-shot-for-medicine-nuclearpowered-heart-pump.html https://www.nytimes.com/1972/03/21/archives/nuclear-heart-pu... https://www.theatlantic.com/technology/archive/2013/03/the-true-story-of-the-government-programs-that-tried-to-build-an-atomic-heart/274266/ https://www.theatlantic.com/technology/archive/2013/03/the-t...