Ultra-precision machine cutting technology and biomimetic technology

No matter how sophisticated a machine is, it is still incapable of replicating or following the movements of living things. Although science and technology have made remarkable progress, they have yet to reach the level of development of materials and functions that organisms have achieved in the long evolutionary process. For this reason, scientists are trying to emulate the excellent functions of many living organisms on the Earth and to incorporate them into valuable technologies for human life. The Multiscale Biomimetic and Process Technology Laboratory, led by Professor Jeong Hoone of the Department of Mechanical Engineering, carries out research in a wide range of fields, from composite materials to industrial devices using micro- or nano-scale ultra-precision machine cutting.
"The Department of Mechanical Engineering is also researching precision machine cutting technology, among which we are focusing on technology that fuses its characteristics and functions with machines, centering on biomimetic technology. We are researching diverse fields, ranging from biomimetic sensitive composite materials and biomimetic medical devices to wearable sensors and antifouling and antibacterial surfaces."
As Professor Jeong Hoone has focused on making smaller things while researching ultra-precision machine-cutting technology, he has naturally developed an interest in the structure of living organisms such as microorganisms. In other words, he is curious about the structure and function of living organisms that are small enough to be invisible to the eye and move freely.
“Microorganisms are incredibly minute, measuring no more than a few dozen micrometers (μm) in size, and have the ability to move quickly. As such, one could say that a microorganism is a very precise robot in its own right. The fine hairs and cilia sprouting on the surface of its cells are what make a microorganism move. The excellent functions of most living organisms, not just cilia, are attributable to their unique micro/nanostructures, and many scientists are already carrying out research in this area, but it takes a long time to develop artificially implemented technology. My research team is also interested in the unique structures of living organisms and is constantly trying to combine them with ultra-precision machine cutting technology.”

Development of thin and long synthesis technology

In July, Professor Jeong Hoone's team attracted considerable attention when it succeeded in developing a technology that can synthesize a long, thin ciliary structure by stacking nanometer-sized magnetic particles on top of each other. This achievement was only made possible by the team’s unceasing exploration of the structures of living organisms.
The team is also interested in the unique structure of the cilia of microorganisms, also called flagella, and is trying to combine it with ultra-precision machine cutting technology. Cilia have a very high length-to-diameter 1:100. In other words, the diameter is around tens of nanometers (nm), while the length is tens of micrometers (μm).
"The technology for reducing diameters to nanometers has already advanced significantly. However, the main problem was how to make them tall and dense. We have been trying for several years but we keep hitting a wall. In fact, we have been struggling with the same problem for about two years.”
The clue to solving the problem was found at an unexpected moment. Quite by chance, Kang Min-soo, a student member of the research team, applied nanoparticles in the vapor phase in specific process conditions and confirmed that they had been synthesized.
“If one looks closely at cilia, one can see that proteins are precisely formed like mechanical structures. Nanoparticles must be stacked vertically high like a building to create artificial cilia, but conventional methods, such as putting liquid raw materials into a frame, have yet to work. The student members of our research team, thinking and working in various ways, have developed a synthesis method to overcome the problem.”
The research team applied a synthesis method by using magnetic force. The method consists in arranging nickel metal fragments in places where you want the cilia strands to sprout and then scattering magnetic nanoparticles from above and stacking them in rows. The underlying principle is that when a strong magnetic force forms around nickel, it attracts magnetic nanoparticles. Thanks to a finely designed magnetic force, the nanoparticles are individually assembled into the desired shape. With this technology, the research team stacked up to 54 particles with a diameter of 373 nanometers (nm, 1/1 billionth of a meter). The aspect ratio is over 50, the highest ever among artificial cilia synthesized so far.
"We expect that this technology will assist with the development of nano-robots that can be injected into the body and ultra-fine drive devices that can remove pollutants. Especially in the medical sector, there is steady demand for ultra-small robots. However, current micro-level robots have limitations as regards the areas of the body into which they can be inserted, but at the nano level, they can be inserted almost anywhere, opening up the possibility of numerous innovations in medical treatment.”

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Competing with the world on the strength of our competitiveness

In recent years, convergence with other fields has become essential, but it is highly complex, which is why we should pay close attention to the results of other researchers, regardless of the field. Professor Jeong Hoone also frequently reviews excellent papers published by other researchers in order to get ideas for research and obtain information on new theories.
"I think it's an important habit to read many papers by other researchers. Identifying the strengths and weaknesses of their papers gives me a chance to look back at our own research methods and theories. I can also have an attitude to collaborate with an open mind.”
Recently, the research team has engaged in frequent communication and collaboration with research teams at the National Institute of Ecology. Living organisms on the Earth have many different functions, but many principles still need to be discovered, which means that there are still many fields to explore.
“As the structures, functions, and principles of living organisms studied in biology are converged with engineering, various results have emerged in the world under realistic simulation technology and biomimetic technology. The future direction of our research will tend towards technologies that mimic methods similar to those of living organisms. In robotics, many experiments have used materials as soft as human skin to wrap hardware. Therefore, if we create and grow our biomimetic technology, we can achieve a higher level of technological development.”
The research team also intends to conduct more active collaborative research with research teams in other fields, such as control engineering, electronics, biomaterials, and medical engineering. The goal is to reach the “system level” without stopping at merely developing materials and structures.
"Even if you consider a TV, it must first have a liquid crystal, and it must also incorporate complex elements such as a hard cover that wraps the exterior and an electrical structure that allows current to flow. The system level is our ultimate goal of reaching beyond the development of artificial cilia towards a stage that encompasses all research and development processes, up to medical robots using them. It is a blueprint that I'm creating in order to grow into a research team with global competitiveness.
Professor Jeong Hoone said that he hoped the research team and each of the team’s researchers and student members would have confidence and a broad perspective in order to be as competitive as world-class research teams. He tries to create opportunities for them to visit overseas academic conferences or interact with other universities to overcome the limitations of their small laboratory.
"All our students are capable enough to compete with world-class research teams. If we don't settle for the present and strive tirelessly to develop original technologies by exploiting our strengths, we will naturally grow into a world-class research team, and we will continue to move forward as a research team that can push ahead without setting any limits."