Brain Research Institute, University of Zurich, Zurich, 8057, Switzerland.
Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110, Freiburg, Germany.
Adv Healthc Mater. 2024 Sep;13(24):e2303401. doi: 10.1002/adhm.202303401. Epub 2024 Feb 23.
Extracellular recordings with planar microelectrodes are the gold standard technique for recording the fast action potentials of neurons in the intact brain. The introduction of microfabrication techniques has revolutionized the in vivo recording of neuronal activity and introduced high-density, multi-electrode arrays that increase the spatial resolution of recordings and the number of neurons that can be simultaneously recorded. Despite these innovations, there is still debate about the ideal electrical transfer characteristics of extracellular electrodes. This uncertainty is partly due to the lack of systematic studies comparing electrodes with different characteristics, particularly for chronically implanted arrays over extended time periods. Here a high-density, flexible, and thin-film array is fabricated and tested, containing four distinct electrode types differing in surface material and surface topology and, thus, impedance. It is found that recording quality is strongly related to electrode impedance with signal amplitude and unit yield negatively correlated to impedance. Electrode impedances are stable for the duration of the experiment (up to 12 weeks) and recording quality does not deteriorate. The findings support the expectation from the theory that recording quality will increase as impedance decreases.
使用平面微电极进行细胞外记录是记录完整大脑中神经元快速动作电位的金标准技术。微制造技术的引入彻底改变了神经元活动的活体记录，并引入了高密度、多电极阵列，提高了记录的空间分辨率和可同时记录的神经元数量。尽管有这些创新，关于细胞外电极的理想电传输特性仍存在争议。这种不确定性部分是由于缺乏系统的研究比较具有不同特性的电极，特别是对于长期植入的阵列在较长时间内。在这里，制作和测试了一种高密度、灵活和薄膜阵列，包含四种不同的电极类型，它们在表面材料和表面拓扑结构（因此，阻抗）上有所不同。结果发现，记录质量与电极阻抗密切相关，信号幅度和单位产量与阻抗呈负相关。在整个实验过程中（长达 12 周），电极阻抗是稳定的，记录质量不会恶化。这些发现支持了理论上的预期，即随着阻抗的降低，记录质量将会提高。
