How Things Work: Nanorobots

Robots come in all shapes and sizes. Science fiction and modern technology have introduced people to a variety of robots ranging from the rovers that track the surface of distant planets to the ever-popular R2-D2 of Star Wars fame.

However, a whole new host of robots, called “nanorobots,” are in the making and are unlike anything ever seen before.

The whole idea behind nanorobots is that when a patient takes a pill to treat any disease, instead of having a host of chemicals inside it, the pill will have an actual working machine inside it — a nanorobot. The nanorobot will contain small quantities of the needed medicine and will actually travel to the target organ and deliver the medicine at the specific site. The major advantage of this technique is that the medicine does not have to travel through various pathways in the body, like the blood stream, and hence will not get diluted by the time it reaches its target. Drugs delivered through nanorobots will thus be far more effective than drugs delivered normally.

Nanorobots will be especially useful in treating diseases such as cancer where specific cells have to be targeted. The major disadvantage of the present chemotherapy is that it targets all kinds of cells; the medicine cannot distinguish between the healthy cells and the cancerous cells. Hence, although many of the cancerous cells die because of the drugs, many healthy cells die as well and this weakens the patient to a great extent. Nanorobots will be able to specifically target the cancerous cells and deliver the drugs only to those cells.

Although the device will be remarkably useful, it is also difficult to make. Perhaps the greatest difficulty faced by the developers is how to navigate the robots to the target organs. Even if they manage to build a robot small enough to be encased in a pill, the robot will be useless if all it does is lie around in the depths of the stomach. One of the proposed mechanisms for detecting where the nanorobot is within the body is to use ultrasonic signals. The nanorobot could continuously emit ultrasonic signals, which could be recorded and the location of the nanorobot could thus be determined.

Another approach involves the use of miniature cameras that could be attached to the nanorobot and sent into the body along with the robot. Doctors would then be able to view the course of the robot through the body. However, creating such small cameras poses a problem and would require a lot more research. Until now, the most practical approach has been the use of magnetic resonance imaging (MRI). As reported in an article in MIT Technology Review, researchers at the École Polytechnique de Montréal in Canada recently discovered that bacteria with magnetic particles could be maneuvered inside the body using MRI machines.

By changing the surrounding magnetic field, the bacteria could be forced to move in any desired direction. The technique could be extended for nanorobot navigation. Since nearly all the hospitals today have MRI scanners, this method could easily be employed in present day hospital settings. The second problem after navigation is powering the nanorobot. The nanorobot, after all, is a machine and all machines need some source of power. The most obvious approach is to create a power source small enough to be fitted on the nanorobot. However, the major problem with such an approach is that a small enough battery would not be able to provide the large amount of power that the nanorobot needs, and so alternative power sources need to be considered.

One of the best solutions to this problem is to use the human body as a power source. The nanorobot will be travelling through the bloodstream to reach its target. The blood contains a number of charged particles in it, which if used in the right way, could form a battery for the nanorobot. The nanorobot could be equipped with electrodes, and with the help of these electrodes and the electrolytes in the surrounding bloodstream, a suitable power source could be created. Another option is to provide the nanorobot with a host of chemicals that would burn when they react with blood. The energy released by the combustion would then provide the nanorobot with the needed power.

However, even if the problem of power and navigation is solved, the problem of rejection by the body’s immune system still needs to be countered. The nanorobots also have to be safe, as having them harm the body will completely belie the purpose of their creation.

More research needs to be conducted in order to make small, safe robots that can be used in patients. For now, at least, nanorobots remain a distant prospect.