RespirocytesA Mechanical Artificial Red Cell: Exploratory Design in Medical Nanotechnology

-Robert A. Freitas Jr.

Presented byUmaMaheswari Ethirajan

Overview Introduction Preliminary Design Issues Nanotechnological design of Respiratory

Gas carriers Baseline design Therapeutics Safety and Bio-compatibility Applications Summary and Conclusion

Introduction Molecular manufacturing processes applications. Medical implications – precise interventions at

cellular and molecular levels. Medical nanorobots – research, diagnoses and

cure. Preliminary design for artificial mechanical

erythrocyte or Red Blood Cell (RBC) – Respirocyte.

Preliminary Design Issues

Biochemistry of respiratory gas transport – oxygen and carbon-dioxide.

Existing Artificial Respiratory Gas carriers Hemoglobin Formulations

50% more O2 than natural RBCs. Dissociates to dimers, Binds to O2 more tightly, Hemoglobin

oxidized. Fluorocarbon Emulsions

Physical solubilization – emulsions of droplets Shortcomings of Current technologies

Too short life time Not designed for CO2 transport vasoconstriction

Design of Respiratory Gas carriers Pressure Vessel

Spherical, Flawless diamond or sapphire 1000atm – optimal gas molecule packing

density Discharge time very less - <2 minutes

Recharging with O2 from lungs

Respiratory gas equilibrium – more CO2

Provide additional tankage for CO2

Means for gas loading and unloading

Molecular Sorting Rotors

Binding site pockets – rims – 12 arms

Selective binding Eject – cam action Fully reversible – load

and unload 7nm x 14nm x 14nm 2 x 10-21 kg Sorts molecules of 20

or fewer atoms 106 molecules/ sec

Molecular Sorting Rotors (cont’d) Power saving – generator subsystem 90% occupancy of rotor binding sites Multi-stage cascade – virtually pure gases

Sorting Rotors binding sites O2, CO2, Water, Glucose

Device Scaling On-board computer – 58nm diameter sphere 37.28% of tank surface – sorting rotors Reasonable range – 0.2 to 2 microns Present study assumes – approx. 1 micron

Buoyancy control Loading and unloading water ballast Very useful – exfusion from blood Example – specialized centrifugation apparatus

Nanotechnological Design of Respiratory Gas carriers (cont’d)

Baseline Design - Power

glucose & oxygen – Mechanical Energy Glucose – blood & Oxygen – onboard storage Glucose Engine – 42nm x 42nm x 175nm Output is water – approx. glucose absorbed Fuel tank – glucose storage – 42nm x 42nm x

115nm Mechanical or hydraulic power distribution

Rods & gears Pipes & valves

Control – onboard computer

Baseline Design - Communications Physician – broadcast signals Modulated compressive pressure pulses Mechanical transducers – surface of

respirocytes Transducers – pressure driven actuators Internal Communication

Hydraulic - Low pressure acoustic spikes Mechanical - Mechanical rods and couplings

Baseline Design - Sensors

Sorting rotors – quantitative molecular concentration sensors

Internal pressure sensors – gas tank loading, ballast and glucose fuel tanks, internal/external temperature sensors.

Baseline Design – Onboard Computation

104 bit/sec computer 105 bits of internal memory

Gas loading and unloading Rotor field and ballast tank management Glucose engine throttling Power distribution Interpretation of sensor data Self-diagnoses and control of protocols

Glucose rotor, Tank, Engine and Flue Assembly in 12-station Respirocyte baseline design

Pumping Station Layout

Equatorial Cutaway View of Respirocyte

Polar Cutaway View of Respirocyte

Baseline Design – Tank Chamber Design

Diamondoid honeycomb or geodesic grid skeletal framework

Perforated compartment walls Present design – CO2 and O2 separate Proposed – same chamber Disadvs

Respiration control – CO2 level

Reverse CO2 overloading Reduction of maximum outgassing rate

Therapeutics Minimum Therapeutic dose

Human blood O2 capacity – 8.1 x 1021 molecules Each respirocyte – 1.51 x 109 O2 molecules Full duplication – 5.36 x 1012 devices Hypodermal injection or transfusion

Maximum Augmentation Dose Fully O2 charged dose – 9.54 x 1014 respirocytes 12 minutes and peak exertion 3.8 hours at rest

Control Protocols Precise external control by physician Programmable for sophisticated behaviors

Safety and Bio-compatibility Mechanical failure modes

Device overheating Non-combustive device explosion Radiation damage

Coagulation Inflammation Phagocytes

Applications Transfusions Treatment of Anemia Fetal and Child-related disorders Respiratory Diseases Cardiovascular and Neurovascular applications Tumor therapy and Diagnostics Asphyxia Underwater breathing Endurance oriented sport events Anaerobic and aerobic infections Veterinary medicine

Summary and Conclusion Artificial erythrocyte Avoiding carbonic acidity – mechanical transport

of CO2 236 times more O2 per unit volume than natural

RBCs Tough diamondoid material Numerous sensors On-board nano-computer Remotely programmable Lifespan of 4 months Future advances in molecular machine system

engineering – actual construction.

References Drexler KE. Nanosystems

: Molecular Machinery, Manufacturing, and Computation. New York: John Wiley & Sons, 1992.

www.foresight.org

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