As technology advances, things don’t always become bigger and better, objects also become smaller. In fact, nanotechnology is one of the fastest-growing technological fields, worth over 1 trillion USD, and it’s forecast to grow by approximately 17% over the next half-decade. Nanobots are a major part of the nanotechnology field, but what are they exactly and how do they operate? Let’s take a closer look at nanobots to understand how this transformative technology works and what it’s used for.
What Are Nanobots?
The field of nanotechnology is concerned with the research and development of technology approximately one to 100 nanometres in scale. Therefore, nanorobotics is focused on the creation of robots that are around this size. In practice, it’s difficult to engineer anything as small as one nanometer in scale and the term “nanorobotics” and “nanobot” is frequently applied to devices which are approximately 0.1 – 10 micrometers in size, which is still quite small.
It’s important to note that the term “nanorobot” is sometimes applied to devices which interact with objects at the nanoscale, manipulating nanoscale items. Therefore, even if the device itself is much larger, it may be considered a nanorobotic instrument. This article will focus on nanoscale robots themselves.
Much of the field of nanorobotics and nanobots is still in the theoretical phase, with research focused on solving the problems of construction at such a small scale. However, some prototype nanomachines and nanomotors have been designed and tested.
Most currently existing nanorobotic devices fall into one of four categories: switches, motors, shuttles, and cars.
Nanorobotic switches operate by being prompted to switch from an “off” state to an “on” state. Environmental factors are used to make the machine change shape, a process called conformational change. The environment is altered using processes like chemical reactions, UV light, and temperature, and the nanorobotic switches shift into different forms as a result, able to accomplish specific tasks.
Nanomotors are more complex than simple switches, and they utilize the energy created by the effects of the conformational change in order to move around and affect the molecules in the surrounding environment.
Shuttles are nanorobots that are capable of transporting chemicals like drugs to specific, targeted regions. The goal is to combine shuttles with nanorobot motors so that the shuttles are capable of a greater degree of movement through an environment.
Nanorobotic “cars” are the most advanced nanodevices at the moment, capable of moving independently with prompts from chemical or electromagnetic catalysts. The nanomotors that drive nanorobotic cars need to be controlled in order for the vehicle to be steered, and researchers are experimenting with various methods of nanorobotic control.
Nanorobotics researchers aim to synthesize these different components and technologies into nanomachines that can complete complex tasks, accomplished by swarms of nanobots working together.
Photo: Photo: ” Comparison of the sizes of nanomaterials with those of other common materials.” Sureshup vai Wikimedia Commons, CC BY 3.0 (https://en.wikipedia.org/wiki/File:Comparison_of_nanomaterials_sizes.jpg)
How Are Nanobots Created?
The field of nanorobotics is at the crossroads of many disciplines and the creation of nanobots involves the creation of sensors, actuators and motors. Physical modeling must be done as well, and all of this must be done at nanoscale. As mentioned above, nanomanipulation devices are used to assemble these nano-scale parts and manipulate artificial or biological components, which includes the manipulation of cells and molecules.
Nanorobotics engineers must be able to solve a multitude of problems. They have to address issues regarding sensation, control power, communications, and interactions between both inorganic and organic materials.
The size of a nanobot is roughly comparable to biological cells, and because of this fact future nanobots could be employed in disciplines like medicine and environmental preservation/remediation. Most “nanobots” that exist today are just specific molecules which have been manipulated to accomplish certain tasks.
Complex nanobots are essentially just simple molecules joined together and manipulated with chemical processes. For instance, some nanobots are comprised of DNA, and they transport molecular cargo.
How Do Nanobots Operate?
Given the still heavily theoretical nature of nanobots, questions about how nanobots operate are answered with predictions rather than statements of fact. It’s likely that the first major uses for nanobots will be in the medical field, moving through the human body and accomplishing tasks like diagnosing diseases, monitoring vitals, and dispensing treatments. These nanobots will need to be able to navigate their way around the human body and move through tissues like blood vessels.
Navigation
In terms of nanobot navigation, there are a variety of techniques that nanobot researchers and engineers are investigating. One method of navigation is the utilization of ultrasonic signals for detection and deployment. A nanobot could emit ultrasonic signals that could be traced to locate the position of the nanobots, and the robots could then be guided to specific areas with the use of a special tool that directs their motion. Magnetic Resonance Imaging (MRI) devices could also be employed to track the position of nanobots, and early experiments with MRIs have demonstrated that the technology can be used to detect and even maneuver nanobots. Other methods of detecting and maneuvring nanobots include the use of X-rays, microwaves and radio-waves. At the moment, our control of these waves at the nano-scale is fairly limited, so new methods of utilizing these waves would have to be invented.
The navigation and detection systems described above are external methods, relying on the use of tools to move the nanobots. With the addition of onboard sensors, the nanobots could be more autonomous. For instance, chemical sensors included onboard nanobots could allow the robot to scan the surrounding environment and follow certain chemical markers to a target region.
Power
When it comes to powering the nanobots, there are also a variety of power solutions being explored by researchers. Solutions for powering nanobots include external power sources and onboard/internal power sources.
Internal power solutions include generators and capacitors. Generators onboard the nanobot could use the electrolytes found within the blood to produce energy, or nanobots could even be powered using the surrounding blood as a chemical catalyst that produces energy when combined with a chemical the nanobot carries with it. Capacitors operate similarly to batteries, storing electrical energy that could be used to propel the nanobot. Other options like tiny nuclear power sources have even been considered.
As far as external power sources go, incredibly small, thin wires could tether the nanobots to an outside power source. Such wires could be made out of miniature fiber optic cables, sending pulses of light down the wires and having the actual electricity be generated within the nanobot.
Other external power solutions include magnetic fields or ultrasonic signals. Nanobots could employ something called a piezoelectric membrane, which is capable of collecting ultrasonic waves and transforming them into electrical power. Magnetic fields can be used to catalyze electrical currents within a closed conducting loop contained onboard the nanobot. As a bonus, the magnetic field could also be used to control the direction of the nanobot.
Locomotion
Addressing the problem of nanobot locomotion requires some inventive solutions. Nanobots that aren’t tethered, or aren’t just free-floating in their environment, need to have some method of moving to their target locations. The propulsion system will need to be powerful and stable, able to propel the nanobot against currents in its surrounding environment, like the flow of the blood. Propulsion solutions under investigation are often inspired by the natural world, with researchers looking at how microscope organisms move through their environment. For instance, microorganisms often use long, whip-like tails called flagella to propel themselves, or they use a number of tiny, hair-like limbs dubbed cilia.
Researchers are also experimenting with giving robots small arm-like appendages that could allow the robot to swim, grip, and crawl. Currently, these appendages are controlled via magnetic fields outside the body, as the magnetic force prompts the robot’s arms to vibrate. An added benefit to this method of locomotion is that the energy for it comes from an outside source. This technology would need to be made even smaller to make it viable for true nanobots.
There are other, more inventive, propulsion strategies also under investigation. For instance, some researchers have proposed using capacitors to engineer an electromagnetic pump that would pull conductive fluids in and shoot it out like a jet, propelling the nanobot forward.
Regardless of the eventual application of nanobots, they must solve the problems described above, handling navigation, locomotion, and power.
What Are Nanobots Used For?
As mentioned, the first uses for nanobots will likely be in the medical field. Nanobots could be used to monitor for damage to the body, and potentially even facilitate the repair of this damage. Future nanobots could deliver medicine directly to the cells that need them. Currently, medicines are delivered orally or intravenously and they spread throughout the body instead of hitting just the target regions, causing side effects. Nanobots equipped with sensors could easily be used to monitor for changes in regions of cells, reporting changes at the first sign of damage or malfunction.
We are still a long way away from these hypothetical applications, but progress is being made all the time. As an example, in 2017 scientists created nanobots that targeted cancer cells and attacked them with a miniaturized drill, killing them. This year, a group of researchers from ITMO University designed a nanobot composed of DNA fragments, capable of destroying pathogenic RNA strands. DNA-based nanobots are also currently capable of transporting molecular cargo, The nanobot is made of three different DNA sections, maneuvering with a DNA “leg” and carrying specific molecules with the use of an “arm”.
Beyond medical applications, research is being done regarding the use of nanobots for the purposes of environmental cleanup and remediation. Nanobots could potentially be used to remove toxic heavy metals and plastics from bodies of water. The nanobots could carry compounds that render toxic substances inert when combined together, or they could be used to degrade plastic waste through similar processes. Research is also being done on the use of nanobots to facilitate the production of extremely small computer chips and processors, essentially using nanobots to produce microscale computer circuits.
