物理化学学报2020，Vol.36Issue(12)：109-115,7.DOI:10.3866/PKU.WHXB202005033
轻掺杂硅基神经电极的光噪声消减
Light-Induced Noise Reduction of Lightly Doped Silicon-based Neural Electrode
摘要
Abstract
Silicon-based neural probes are practical tools for recording neural cell firing.A single silicon-based needle with a width of only 70 μm,prepared using the standard complementary metal-oxide-semiconductor(CMOS)process technology,can contain thousands of electrode-recording sites.Optogenetics has made control over neuronal activity more precise.By recording the electrical activity of neurons stimulated by light,more information about brain activity can be recorded and analyzed.When yellow light or blue light is used to stimulate neurons,the photon energy is greater than the forbidden bandwidth of the silicon substrate,and the valence-band electrons are excited to the conduction band,generating electron-hole pairs.The photoinduced carrier in the silicon substrate severely disrupts the probe's signal-to-noise ratio.Decreasing the disturbance caused by light is a pragmatic way to execute recording and stimulating simultaneously.The traditional noise reduction method involves using heavily doped silicon as the substrate,reducing the carrier life by increasing the impurity concentration,and then reducing the noise of the silicon electrode under illumination.However,the heavily doped silicon substrate has more lattice defects than its lightly doped counterparts,which makes the silicon electrode fragile,and this method is not compatible with the standard CMOS process technology.On analyzing the photoinduced noise mechanism of manufacturing electrodes on lightly doped silicon substrates,we found that the inhomogeneous distribution of carriers generated by light excitation polarizes lightly doped silicon substrates.The potential caused by photoinduced polarization will affect the electrodes fabricated on it.Metalizing and grounding the lightly doped silicon substrate will effectively decrease the polarization potential.On using this method,the noise amplitude caused by the illumination can drop to 0.87％of the original value.To ensure an appropriate firing rate of neurons,the photo-stimulation frequency was chosen to be 20 Hz.Under the illumination of 1 mW·mm-2,the background noise of the electrode could be controlled below 45 μV,which meets the needs for general optogenetics applications.Modification of the lightly doped silicon substrate will meet the requirements of the neural electrode for optogenetics applications.Unlike the traditional method of reducing light-induced noise by heavily doping the entire substrate,the noise reduction method of lightly doped silicon substrate is compatible with the standard CMOS process technology.It provides a noise cancellation method for the preparation of silicon-based neural microelectrodes with dense recording sites and high channel count using standard CMOS processes.关键词
光噪声/光生载流子/光遗传学/轻掺杂/硅基神经微探针Key words
Light-induced noise/Photoinduced carrier/Optogenetics/Lightly doped/Silicon-based neural probe分类
化学化工引用本文复制引用
魏春蓉,刘媛媛,赵姗姗,归强,陈弘达,王飞,裴为华,刘智多,毛旭瑞,赵宏泽,王思凯,王毅军,杨晓伟..轻掺杂硅基神经电极的光噪声消减[J].物理化学学报,2020,36(12):109-115,7.基金项目
The project was supported by the National Key Technologies Research and Development Program of China(2017YFA0205903,2017YFA0701100,2016YFB0402405) （2017YFA0205903,2017YFA0701100,2016YFB0402405）
the National Natural Science Foundation of China(61634006,61671424) （61634006,61671424）
the Strategic Priority Research Program of Chinese Academy of Sciences Pilot Project(XDB32030100,XDB32040200) （XDB32030100,XDB32040200）
the Key Research Programs of Frontier Sciences,CAS(QYZDY-SSW-JSC004).国家重大研究发展计划项目(2017YFA0205903,2017YFA0701100,2016YFB0402405),国家自然科学基金(61634006,61671424),中国科学院战略性先导科技专项(XDB32030100,XDB32040200),中国科学院前沿科学重点研究项目(QYZDY-SSW-JSC004)资助 （QYZDY-SSW-JSC004）
