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A Mechanical Artificial Red Cell:
Exploratory Design in Medical Nanotechnology

by Robert A. Freitas Jr.

Research Fellow, Institute for Molecular Manufacturing (IMM)
Palo Alto, California USA

© Copyright 1996-1999, Robert A. Freitas Jr.
All rights reserved.

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The original version of the refereed paper describing respirocytes was first submitted for publication on 17 April 1996. © Copyright 1996 Robert A. Freitas Jr. This is the revised version of that 1996 paper.

A somewhat abbreviated version of this paper was ultimately published in 1998 as: Robert A. Freitas Jr., "Exploratory Design in Medical Nanotechnology: A Mechanical Artificial Red Cell," Artificial Cells, Blood Substitutes, and Immobil. Biotech. 26(1998):411-430. Portions of the 1996 paper differ slightly from the 1998 published version.

NOTE: 5 July 2000: Thanks to work done by Patrick Macé, "Respirocytes" has been translated into French and is available in PDF format as "LES RESPIROCYTES: Un globule rouge artificiel" (868 K). Requires ACROBAT READER by ADOBE.


Abstract: Molecular manufacturing promises precise control of matter at the atomic and molecular level, allowing the construction of micron-scale machines comprised of nanometer-scale components. Medical nanomachines will be among the earliest applications. The artificial red blood cell or "respirocyte" proposed here is a bloodborne spherical 1-micron diamondoid 1000-atm pressure vessel with active pumping powered by endogenous serum glucose, able to deliver 236 times more oxygen to the tissues per unit volume than natural red cells and to manage carbonic acidity. An onboard nanocomputer and numerous chemical and pressure sensors enable complex device behaviors remotely reprogrammable by the physician via externally applied acoustic signals. Primary applications will include transfusable blood substitution; partial treatment for anemia, perinatal/neonatal and lung disorders; enhancement of cardiovascular/neurovascular procedures, tumor therapies and diagnostics; prevention of asphyxia; artificial breathing; and a variety of sports, veterinary, battlefield and other uses.

Key Words: Anemia -- Artificial Lung -- Artificial Red Cell -- Asphyxia -- Blood Substitutes -- Decompression Sickness -- Gas Transport -- Microrobotics -- Nanomedicine -- Nanorobotics -- Nanotechnology -- Oxygen Carrier -- Respiration -- Respirocytes -- Reversible Oxygen Binding

Short Title: Mechanical Artificial Red Cell


Table of Contents

  1. Introduction  
  2. Preliminary Design Issues  
    2.1 Existing Artificial Respiratory Gas Carriers  
    2.1.1 Hemoglobin Formulations  
    2.1.2 Fluorocarbon Emulsions  
    2.1.3 Shortcomings of Current Technology  
    2.2 Nanotechnological Design of Respiratory Gas Carriers  
    2.2.1 Pressure Vessel  
    2.2.2 Molecular Sorting Rotors  
    2.2.3 Sorting Rotor Binding Sites  
    2.2.4 Device Scaling  
    2.2.5 Buoyancy Control Using Water Ballast  
  3. Baseline Design  
    3.1 Power  
    3.2 Communications  
    3.3 Sensors  
    3.4 Onboard Computation  
    3.5 Baseline Configuration  
    3.6 Tank Chamber Design  
  4. Therapeutics and Performance  
    4.1 Minimum Therapeutic Dose  
    4.2 Maximum Augmentation Dose  
    4.3 Respirocyte Control Protocols  
  5. Safety and Biocompatibility  
    5.1 Mechanical Failure Modes  
    5.1.1 Device Overheating  
    5.1.2 Noncombustive Device Explosion  
    5.1.3 Radiation Damage  
    5.2 Interference with Erythropoiesis  
    5.3 Surface Electrical Thrombogenicity  
    5.4 Mechanical Thrombogenesis  
    5.5 Trimming of Cellular Glycocalyx  
    5.6 Red Cell Aggregation and Non-RBC Margination  
    5.7 Coagulation, Inflammation and Phagocytosis  
  6. Applications  
    6.1 Transfusions & Perfusions Modes  
    6.2 Treatment of Anemia  
    6.3 Fetal and Child-Related Disorders  
    6.4 Respiratory Diseases  
    6.5 Cardiovascular and Neurovascular Applications  
    6.6 Tumor Therapy and Diagnostics  
    6.7 Asphyxia  
    6.8 Underwater Breathing  
    6.9 Other Applications  
    6.10 Device Testing and FDA Approval  
  7. Summary and Conclusions  
  8. Acknowledgments  
  9. References  

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© Copyright 1996-1999, Robert A. Freitas Jr. All rights reserved.