In this blog post, we will explore the concept of micro- and nano-robots, their potential applications in the medical field, the advantages they offer in improving existing treatments, and the limitations and side effects of this technology.
While medical technology has been advancing by leaps and bounds recently, there is a growing need for methods to address new diseases and treat existing ones more effectively. Furthermore, existing disease treatment methods must also be continuously improved. One solution to this is micro- and nano-robots. In the context of micro- and nano-robots, “micro” is a prefix meaning one-millionth, and “nano” means one-billionth; thus, these can be understood as extremely tiny bio-robots. Micro-robots generally refer to robots with a diameter of 1 mm or less. So, let’s explore how these robots can contribute to improving existing treatments, as well as the potential side effects and limitations that may arise in the process.
Micro- and nano-robots are being developed in three main types: robots that move or remain stationary within organs such as the small or large intestine (Type A), robots that explore tubes (Type B), and robots inserted into human blood vessels (Type C). Among these, robots inserted into blood vessels are the smallest and are widely used in disease treatment; using such robots in drug therapy can significantly improve existing treatment methods. For example, in conventional cancer treatment, when drugs are injected into the body, they spread randomly, damaging not only cancer cells but also healthy cells, which sometimes results in the drugs failing to reach the cancer cells effectively. However, if nanorobots can be used to deliver drugs precisely to cancer cells, treatment can be more effective by concentrating the drugs on the cancer cells while minimizing damage to healthy cells. In other words, using nanorobots to precisely deliver drugs to target cells allows for the effective treatment of diseases.
A prime example of this is the bacteriabot. Bacteribots are being developed to deliver drugs to cancer cells by combining bacteria with drugs. When the toxicity of the bacteria is neutralized and they are combined with microstructures containing anticancer drugs, the bacteria use their flagella to track down cancer cells. The robots recognize cancer cells based on specific substances secreted by them, and upon reaching a cancer cell, the microstructure bursts, releasing the drug. The feasibility of these robots has been verified in experiments using microbots on mice with solid tumors.
Furthermore, using micro- and nano-robots that move within organs makes it possible to observe even the finest details of organs that were previously difficult to see with endoscopy. Development is also underway on methods such as inserting robots along with endoscopes to observe the interior of organs, or attaching small surgical instruments to robots and inserting them into the body—for example, surgical robots designed for the eye. Micro- and nano-robots not only enable delicate surgeries that are difficult to perform by hand but can also improve existing surgical methods. For example, in surgeries to unblock clogged blood vessels, the use of thin metal wires in the past posed a risk of damaging the vessels; however, using nano-robots can reduce this risk.
However, since we are still in the stage of developing micro-scale robots, and experiments with nano-scale robots are still rare, this technology remains in an incomplete stage. First, development regarding the drive mechanism and power source—the most critical elements of a robot—is still insufficient. Engines that are suitable for the size of micro-robots and can serve as their own power source must be developed through further research. Furthermore, there are shortcomings in the control of the robot’s position and movement. It is currently difficult to position the robot precisely where desired or steer it in the intended direction as it moves through blood vessels; while it can move in a straight line freely, it cannot yet perform rotational or translational movements perfectly. Given these limitations on the robot’s freedom of movement and positional control, it is difficult to fully leverage the advantages of micro- and nano-robots. In other words, micro- and nano-robots still have many shortcomings that prevent their practical application in humans. Furthermore, while it is possible to insert a robot into a blood vessel, removing it afterward is not an easy task. When manufacturing micro- or nano-scale robots, carbon nanotubes are typically included in their components; since these can be quite harmful to the human body, there is a possibility of serious side effects if the robot remains in the blood vessel.
Therefore, micro- and nano-robots can help perform internal organ examinations, surgeries, disease treatment through drug delivery, and exploration of various parts of the body much more effectively. On the other hand, there are still many shortcomings preventing their practical application, as the robots’ self-powered systems are inadequate, their position and motion control are not yet fully independent, and methods for removing them from the body after long-term use have not yet been properly developed. However, interest in micro-robot development is currently growing worldwide, and efforts are underway to address these issues. For example, researchers are exploring methods such as utilizing external magnetic fields or artificial flagella as power sources, or adding body-anchoring mechanisms to robots so they can remain stationary at desired locations. If various research efforts succeed in making these robots suitable for use in the human body, we will be able to assess our internal health without having to visit a hospital. For this reason, micro- and nano-robots are attracting global attention, and their future development and potential are closely watched.
