/sci/ - Science & Math

> Platelets - or thrombocytes - are irregular, roughly spheroidal, 2 micron diameter, anuclear (nucleus-free) blood cells that have an average lifespan of just 5-9 days. Platelets circulate in our bloodstreams and are integral in achieving hemostasis (stoppage of blood flow) after injury. An average, healthy person has between 150,000 and 450,000 platelets per µl (microlitre) of blood. In the event of an injury, platelets gather at the site and activate, becoming sticky and clumping together to form a barrier to seal the damaged blood vessel and stop the bleeding. Platelets are also responsible for releasing clotting factors. The image shows a comparison, from left to right, of a red blood cell, an activated platelet, and a white blood cell. Nature's solution can be quite effective, but it does take valuable time.

> The clottocyte is a, yet theoretical, design by Robert A. Freitas Jr. for an artificial, mechanical platelet. The response time of a clottocyte would be on the order of 100-1000 times quicker than nature's platelets, achieving complete hemostasis in as short as one second.

> Clottocytes would have several distinct advantages over their natural counterparts. For instance platelet function can be adversely affected by drugs such as aspirin. Clottocytes would be immune to the effects of drugs, and could function optimally irregardless of chemical fluctuations in the bloodstream.

>>3843864

>>3503229

I'm more skeptical of the concept of nanobots in general.

The idea that they are possible because cells exist is unrelated. Sure, cells digest, store information and reproduce -- But biological systems are inherently different from the research Kurzweil is basing his claims on. Dry, stiff, covalently-bonded crystals are fundamentally different from the wet, squishy, proteins that make up life. The former works in a UHV at high energies, the latter needs water and dissolves past sixty degrees Celsius.

Moreover, cells are micron-sized, not nanoscale, although most of the medical nanobot designs proposed are essentially microbots with nanoscale appendages. Still, they are far from being some kind of all-powerful machine: Disassemblers, assemblers, computers, a broadcast system and some kind of propulsion system. Yeah, try fitting them all in the volume of a few microns. Again, life has done it, but life is very domain-specific unlike nanobots that are meant to be universally useful. Christ, we can't even get a mechanosynthesis dimer not to explode into an uncontrollable storm of Carbon atoms and I honestly doubt that the whole array of mechanochemical tools required for a robot to be a universal assembler -- Or near-universal, since it would require this for self-replication -- is going to excede the number you can cram into the volume of a few microns.

Even if Kurzweil narrows down these robots to domain-specific nanobots (Something I can't complain about) they are still going to be micron-sized, and they are still going to be damaging the very structures they want to scan.

Pic related it's a medical nanorobot.

> A respirocyte is a theoretical engineering design for an artificial red blood cell about a micron in diameter - a machine that cannot be constructed with current technology. Respirocytes are micron-scale spherical robotic red blood cells comprised of nanometer-scale components, containing an internal pressure of 1000 atmospheres of compressed oxygen and carbon dioxide. The intense pressure would be safely contained in two separate high pressure vessels likely made of pure diamond. At this intense pressure, a respirocyte could hold 236 times more oxygen and carbon dioxide than our natural red blood cells. Respirocytes are an elegantly simplistic design, powered by glucose in the blood and able to manage carbonic acidity via an onboard internal nanocomputer and a multitude of chemical/pressure sensors. 3D nanoscale fabrication will allow respirocytes to be manufactured in practically unlimited supply very inexpensively, directly from a computer design.
> An injection of such nanotechnological devices would enable a person to run at top speed for 15 minutes or remain underwater for four hours on a single breath. Because of their smaller form factor, 1µm diameter, compared with the 8µm diameter of a red blood cell, respirocytes would have potential unique medical applications including the prevention and treatment of ischemia (inadequate oxygen delivery to tissues.) Being smaller in diameter, respirocytes could squeeze into much thinner blood vessels, delivering vital oxygen to cells.