Today, more and more human implantable medical devices have come into people’s lives, such as deep brain stimulators, cardiac pacemakers, implantable insulin pumps, etc., which help human body functions recover. It has a huge effect, but what comes with it is the short life of the equipment and the trouble that it is difficult to operate for a long time.
Under normal circumstances, medical devices implanted in the human body may cause an immune response in surrounding tissues, resulting in inflammation, resulting in a decrease in the performance of the device, a greatly shortened operating time, and even the need for additional replacement of the device.
In response to this challenge, the Korea Institute of Science and Technology ( KIST ) announced joint research and development of a coating technology that can be used to implant medical devices in the human body. This technology can minimize tissue damage during implantation and inhibit inflammation. In addition, the service life of medical devices after coating and lubrication can be as much as four times that of existing devices.
Figure | Related papers (Source: Advanced Science)
related research results were published in Advanced Science in the form of a paper, which is titled "Lubricating non-immunogenic nerves for acute insertion trauma minimization and long-term signal recording "Probe" (A Lubricated Nonimmunogenic Neural Probe for Acute Insertion Trauma Minimization and Long-Term Signal Recording), with Dr. Li Yanze (Il-Joo Cho) from the School of Electrical and Electronic Engineering of Yonsei University as the first author.
The "short life" problem of implantable medical devices raises concerns
In recent years, with the advancement of science and technology, humans have developed a variety of human implantable medical devices, which have been widely used in the clinical field.
Among them, brain-computer interface (BMI) is expected to treat neurological diseases through long-term bidirectional translation of neural information.It has become a typical representative of implantable medical devices, such as deep brain stimulators used to treat Parkinson's disease and other brain diseases.
But what is worrying is that when deep brain stimulators or chips are implanted in the brain, due to the effects of brain immune cells such as microglia, the equipment is usually difficult to operate stably, and the service life is often difficult to reach expectations .
(Source: Advanced Science)
It is understood that seamless integration of the interface between brain tissue and implanted devices is essential for long-term recording and control of neurons. In recent decades, many neural probes of different shapes have been used for firm integration with brain tissue to stably record neural signals from neurons.
However, implanted probes for clinical BMI have not been widely adopted, the main reason is that the probe will produce a biological inflammatory response at the tissue interface.
This type of inflammation is generally caused by acute insertion trauma and chronic foreign body reaction. Acute insertion trauma not only leads to an increase in acute nerve loss, but also accelerates the initial formation of glial sheath around the implanted probe. In addition, due to the foreign body reaction, the thickness of the glial sheath gradually increases, which will eventually drive the neurons away from the electrodes, resulting in interruption of signal recording.
Therefore, how to reduce tissue damage during implantation, inhibit inflammation, and prolong the life of the device has become a key factor in promoting the development of implantable medical devices.
New technology increases the lifespan of nerve probes by more than four times
Based on the inspiration of the smooth leaves of the carnivorous plant Nepenthes , the research team developed a method to form an anti-biofouling coating. Generally, friction occurs when the device is implanted in the human body, and this technology can form a thin and uniform lubricant coating on the surface of the implanted device, and minimize tissue damage by reducing the friction between the device and the tissue.
Figure | Nepenthes (source: Pixabay)
In addition, the coating device exhibits anti-bioadhesion properties,That is to prevent immune cells activated by immune rejection from adhering to the surface of the device.
However, there was no research data at the time showing that the coating can be applied to electronic devices without affecting their signal recording performance and how it interacts in the body.
In order to verify the clinical possibilities of the coating technology, the research team developed a lubricant-coated nerve probe with 32 electrodes to measure brain signals. In the end, observations of brain tissue confirmed that the technology can effectively reduce the human immune response, and the tissue damage that usually occurs during the implantation process is minimized.
Figure | Schematic diagram of the mechanism by which the immune response of the coated probe is minimized compared with the bare probe (Source: Advanced Science)
During the experiment, the team implanted the probe into the rod after coating In animal brains, it was found that more than 90% of the electrodes can observe brain signals, and the number of signals is twice the number of signals obtained by uncoated neural probes.
In addition, because immune cells adhere to the probe surface, the signal amplitude of the uncoated probe will decrease over time. In contrast, the coated probe exhibits good anti-bioadhesive properties, can stably measure brain signals, and the service life of the nerve probe has been extended from 8 weeks to 16 weeks.
"This coated probe shows almost frictionless and anti-biological pollution characteristics, can maximize its electrode performance in the body, can be applied not only to the brain, but also to other parts of the body. For For implantable devices, this technology can significantly extend the service life of such devices." Li Yanze said.
This technology is jointly developed by the Korean Brain Science Research Group and the Yonsei University research team, and is strongly supported by KIST. It is worth mentioning that, as the first government-funded multidisciplinary research institution in South Korea, KIST has formulated a national development strategy based on science and technology and disseminated various important industrial technologies.
Li Yanze said that in the future, this technology will provide more opportunities for the actual use of human implantable medical devices in clinical medicine, and is expected to accelerate its commercialization process by significantly extending the replacement cycle.
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