Chang C H, Chang S R, Lin J S, Lee Y T, Yeh S R, Chen H
Institute of Electronics Engineering, National Tsing Hua University, HsinChu, Taiwan.
Biosens Bioelectron. 2009 Feb 15;24(6):1757-64. doi: 10.1016/j.bios.2008.09.007. Epub 2008 Sep 19.
The ability to monitor and to elicit neural activity with a high spatiotemporal resolution has grown essential for studying the functionality of neuronal networks. Although a variety of microelectrode arrays (MEAs) has been proposed, very few MEAs are integrated with signal-processing circuitry. As a result, the maximum number of electrodes is limited by routing complexity, and the signal-to-noise ratio is degraded by parasitics and noise interference. This paper presents a single-chip neuroelectronic interface integrating oxide-semiconductor field-effect transistors (OSFETs) with signal-processing circuitry. After the chip was fabricated with the standard complementary-metal-oxide-semiconductor (CMOS) process, polygates of specific transistors were etched at die-level to form OSFETs, while metal layers were retained to connect the OSFETs into two-dimensional arrays. The complete removal of polygates was confirmed by high-resolution image scanners, and the reliability of OSFETs was examined by measuring their electrical characteristics. Through a gate oxide of only 7nm thick, each OSFET can record and stimulate neural activity extracellularly by capacitive coupling. The capability of the full chip in neural recording and stimulation was further experimented using the well-characterised escape circuit of the crayfish. Experimental results indicate that the OSFET-based neuroelectronic interface can be used to study neuronal networks as faithfully as conventional electrophysiological tools. Moreover, the proposed simple, die-level fabrication process of the OSFETs underpins the development of various field-effect biosensors on a large scale with on-chip circuitry.
以高时空分辨率监测和激发神经活动的能力对于研究神经元网络的功能已变得至关重要。尽管已经提出了各种微电极阵列（MEA），但很少有MEA与信号处理电路集成。结果，电极的最大数量受到布线复杂性的限制，并且信噪比会因寄生效应和噪声干扰而降低。本文提出了一种将氧化物半导体场效应晶体管（OSFET）与信号处理电路集成的单芯片神经电子接口。该芯片采用标准互补金属氧化物半导体（CMOS）工艺制造后，在芯片级蚀刻特定晶体管的多晶硅栅极以形成OSFET，同时保留金属层以将OSFET连接成二维阵列。通过高分辨率图像扫描仪确认多晶硅栅极已完全去除，并通过测量其电学特性来检查OSFET的可靠性。每个OSFET通过仅7nm厚的栅极氧化物，可以通过电容耦合在细胞外记录和刺激神经活动。使用小龙虾特征明确的逃逸电路进一步实验了整个芯片在神经记录和刺激方面的能力。实验结果表明，基于OSFET的神经电子接口可以像传统电生理工具一样忠实地用于研究神经元网络。此外，所提出的OSFET简单的芯片级制造工艺为大规模开发各种带有片上电路的场效应生物传感器奠定了基础。
