植入式神经微电极

As a key interface device for information communication between human body and external machine, neural electrodes play an important role in brain science, biological electronic medicine and other frontier fields. Originally, metal and semiconductor were used as neural electrode materials, due to their good electrical conductivity. However their hardness are much higher than that of biological tissues (more than 4 orders of magnitude higher), which results in poor biocompatibility. This causes immune responses of biological tissues and electrodes failure. In addition, they are easy to cause damage to biological tissues during the implanting process. In recent years, flexible materials such as conductive polymers, hydrogels and carbon nanotubes are employed to produce flexible neural electrodes. This kind of electrode can reduce the mechanical mismatch across the electronics-tissue interface. Furthermore, the flexible neural electrodes also show advantages in decreasing the impedance between electrode-tissue interface, minimizing biological tissue injury during implantation, ensuring the long-term stability of electrodes and improving their electrical conductivity. All the features are essential for precisely neural stimulation and high quality physiological signal recording. At present, implanted flexible neural microelectrodes attractive many efforts, which requires the combination of new materials, micro-processing technique and neural engineering. The implanted flexible neural electrodes present better performance than other neural electrodes, and many achievements have been gotten in the field of pain suppression, brain-computer interface, human prosthesis and so on. Therefore, the implanted flexible neural electrodes play a more and more important role in clinical application. In this review, we summarize the research progress of implanted neural microelectrodes from three aspects: neural microelectrode, flexible neural electrode and stretchable neural electrode. Firstly, we analyze the problems with rigid implanted neural electrodes. Subsequently, we introduce flexible implanted neural electrodes and demonstrate their advantages. Finally, we discuss how to further optimize the performance of the implanted flexible neural electrodes and prospect their development. It is expected to provide references for the preparation of implanted neural electrodes with excellent properties.