2. What Is It?
In general, the term nanotechnology refers to the field of science and technology pertaining to the creation and use of materials or devices at the nanometer scale.
Nanometer Scale= One-billionth of a meter.

3. Historical Background
The idea behind nanotechnology originated with Nobel Laureate Richard Feyman nearly 50 years ago.
He described the development of tools for molecular engineering which in essence is building materials molecule by molecule.

4. Positional Control, Stiffness, and Elasticity
A central idea in nanotechnology is that of positional control.
There must be a restoring force which acts to return the component to an equilibrium position if displaced. The restoring force is usually assumed to be linear in the displacement.
Resoring Force= Ks x displacement (The constant Ks is a measure of the stiffness of the system.)
The greater the stiffness, the greater the restoring force and the smaller the deviations of the system from its equilibrium position.

5. Nanorobots
Nanorobot parts could range in size from nm, and might be fitted together to make a working machine measuring perhaps microns in diameter.
Carbon will likely be the principal element comprising of a medical nanorobot.
Some devices may have mobility---the ability to swim through the blood, or crawl through body tissue or along walls of arteries. Others will have different shapes, colors, and surface textures, depending on the functions they must perform.

6. Nano robotic Communication
One of the simplest ways to send broadcast type messages into the body is through acoustic messaging.
A device similar to an ultrasound probe would encode messages on acoustic carrier waves at frequencies between 1-10 MHz. Thus the supervising physician can easily send new commands to nanorobots already at work inside the body.
The other half of the process is getting messages back out of the body, from working nanodevices out to the physician. It is convenient to establish an internal communications network that can collect local messages and pass them along to a central location, which the physician can then monitor using sensitive ultrasound detectors to receive the messages.

8. The “Reciprocyte”
An artificial mechanical red cell which measures about 1 micron in diameter and floats along in the bloodstream.
It is a spherical nanorobot made of 18 billion atoms.
The reciprocyte is essentially a tiny pressure tank that mimics the action of the natural hemoglobin-filled red blood cells.
Reciprocytes will have pressure sensors to receive acoustic signals from the doctor, who will use an ultrasound-like transmitter device to give the reciprocytes commands to modify their behavior while they are still inside the patient’s body.

9. Reciprocytes and Red Blood Cells

10. The Reciprocyte’s Functions
The reciprocyte can be pumped full of up to 9 billion oxygen and carbon dioxide molecules. These gases can be released from the tiny tank in a controlled manner.
The gasses are stored onboard at the pressures up to about 1000 atmospheres.
What if you added 1 liter of reciprocytes into your bloodstream?
You could hold your breath for nearly 4 hours if sitting quietly at the bottom of a swimming pool.
If sprinting at top speed, you could run for at least 15 minutes before taking a breath.

11. Chemical Agents
Once a group of cells that needs some chemical substance delivered to it is identified, the chemical agent (e.g. an anti-cancer drug) can be simply released from onboard tanks after the nanorobot arrives on the scene.
A 1 cm3 injection of 1-micron nanodevices could probably hold at least 0.5 cm3 of chemical agent.

12. The Artery Cleaner
Nanorobots are cleaning fatty deposits from the inside wall of an arteriosclerotic artery.

13. Dental Nanorobots
Three remote-controlled nanorobots examine and clean the occlusal surface of a patient's tooth. As an aid to visualization, the artist has depicted the dental nanorobots about 1000 times larger than actual size.

14. Cosmobots
Little robots wait hidden in the skin to dispense the pigments from their stores as programmed by their owners - an alternative to drugstore makeup products and the time required to apply them daily.

15. Virus “Finders”
Floating in an aliquot of laboratory test fluid, these hypothetical early medical nanorobots are testing their ability to find and grasp passing virus particles.

16. Floating Along The Wall Of A Vessel

17. X-Rays & MRI
X-rays as a technique have their good points and bad points. On the plus side, they are powerful enough to be able to pass through tissue, and show density changes in that tissue.
. On the other hand, a scan designed for soft tissue can’t get through if there is any bone blocking the path of the x-rays.

18. What Could Go Wrong?
The incompetence or negligence of medical personnel is always a potential concern.
The most serious problems may devolve from inherent complexity of a trillion machines independently trying to cooperatively work on a very complex repair problem in a short period of time.
One class of malfunction might involve some unexpected emergent machine-machine interaction.
But even in such cases, control over the devices is not lost. The supervising physician, upon observing the fault, would simply shut down one or the other nanorobot species to allow the work to proceed, or would shut down both species and reprogram them both (while they are still inside the body) to avoid the unwanted emergent behavior.

19. Impact of Nanomedicine
Nanomedicine will eliminate virtually all common diseases of the 21th century, virtually all medical pain and suffering, and allow the extension of human capabilities.

20. Ethical/Social Considerations
Ethical issues in merging with computers go beyond the “weird” factor into a whole new kind of problem:
What happens if human beings are made from non-human parts?
Is a baby made from cloned DNA, gestated in a bubble and connected to a cellular phone still human?
It is getting harder and harder to figure out which advance in medicine are worth public research money and which out to be “mothballed.”
Should we spend taxpayers money on clot-breaking machines to extend the average life-span, or work to build other artificial devices much smaller?