Scientists at Singapore’s Nanyang Technological University (NTU Singapore) have developed a small, seed-sized robot that can move over soft, uneven surfaces and perform five surgical functions wirelessly. This has paved the way for the development of robots to make surgeries and treatments more precise.
The small robot, just 4.4 mm long, is controlled by a weak magnetic field and can move, cut biological tissue, release drugs, grab and store tissue samples, or remotely generate heat at any time. Toggling between these features takes less than a second.
The research, led by Associate Professor Lum Guo Zhan from NTU’s School of Mechanical and Aerospace Engineering (MAE), was recently published in an academic journal. advanced materials.
By using magnetic coils to remotely control the robot in the lab, the researchers were able to have it deploy different tools and perform various functions, such as activating small blades to cut tissue or emit heat to targeted areas. This may have implications for approaches under investigation that use heat to treat cancer.
”Most of these magnetic robots can perform only one or two functions. Our latest invention can now perform five functions. Our long-term goal is for doctors to use these minirobots inside the body to move them to target locations and perform treatments.” said Associate Professor Lam, who is a pioneer in small robots made from soft and flexible materials.
Mini robots are being studied around the world as a potential way to make minimally invasive surgical and medical procedures safer, less painful, and more precise.
Such devices could one day allow doctors to perform targeted surgeries deep within the body without the need for large incisions or bulky surgical instruments.
Overcoming major challenges in robotics
To incorporate multiple functions into a robot just a few millimeters long, the NTU team developed a motion-control device that is activated by a magnetic field and can be reprogrammed within a second.
The robot is made of soft magnetic materials such as PDMS and Ecoflex. These materials are silicone-based materials commonly used in soft robotics because they are flexible and can be formed into small structures.
Each of these materials is embedded with 5-micrometer magnetic particles, allowing different parts of the robot to respond to magnetic fields.
At the center of the device is a magnetic module that can magnetize, demagnetize, and remagnetize in different directions.
Each magnetic orientation activates a different function on the robot, allowing the same mobile robot to perform five different functions, including cutting and grasping tissue.
The researchers also designed different regions of the robot so that only some parts, rather than the rest, responded to the same magnetic field.
This means that only part of the robot changes shape in response to magnetic fields to activate tools and functions, while other parts remain stationary and in their current shape, addressing a major limitation of small magnetic robots.
On a small scale, magnetic fields often affect the entire device at once, and all parts act like a single magnet in response to the field, limiting the precision with which different tools can be moved or activated.
Most small magnetic robots are also limited to five degrees of freedom. It can only move along three axes and rotate in two directions.
The NTU robot adds a sixth motion, rolling, allowing it to rotate around its own long axis. This gives the robot more control over how it positions itself. This is important when moving through small, soft and irregular spaces, such as inside the body.
Unlike slime-like mini robots, NTU robots have a sturdy yet flexible body, making them sturdy and easy to retrieve after use.
Tested on living tissue
The NTU team tested the robot’s surgical capabilities using biological tissue models, including chicken liver, and gelatin-based materials that mimic soft tissue.
In laboratory tests, the robot cut through biological tissue, dispensed particles that mimic drug particles, grabbed and stored tissue samples, and generated localized heat after being induced by a magnetic field.
To generate heat, the researchers exposed the robot to a high-frequency alternating magnetic field. This allowed magnetic materials within the device to remotely generate heat, an approach related to magnetic hyperthermia methods being investigated in cancer treatment.
The research team also assessed the biocompatibility of the robot’s material by exposing it to human skin cells under laboratory conditions.
Similar to the control group, more than 99 percent of the cells survived after exposure to the robotic material, suggesting that the material was largely non-toxic under the experimental conditions.
The team, which includes NTU’s MAE graduates Dr. Chelsea Shan Xian Ng and Ms. Yu Xuan Yeoh, and study co-author and current PhD student Nicholas Yong Wei Foo, is currently exploring how future versions can be combined with imaging technology, sensing systems, and clinically realistic artificial organ models that better mimic the physical behavior of human tissue.
Associate Professor Lam is also working with surgeons to understand how the minirobotic system will ultimately fit into real-world clinical workflows.
“For these robots to move closer to practical application, we need to understand not only how they work in the lab, but also how they can be guided, monitored and controlled in real-world medical settings,” he added.
Commenting independently, Dr. Leonard Yong Leong Litt, a senior consultant in the Department of Neurology at the National University Hospital, said:These millimeter-scale, magnetically guided robots are truly remarkable for their ability to traverse complex environments and perform a variety of tasks, such as delivering drugs to predetermined locations, performing biopsies, and remotely administering therapeutic heat. We can imagine that these could replace many aspects of radiointerventional surgery and represent new treatments in medicine.. ”
The research project took seven years and was supported by the NTU Startup Grant, the Agency for Science, Technology and Research (A*STAR), and the NHG Group.
A technical disclosure regarding this innovation was submitted in the following manner: NTUitiveUniversity Innovation and Enterprise Enterprises.
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Nanyang Technological University, Singapore
