Campbell P K, Jones K E, Normann R A
Department of Bioengineering, University of Utah, Salt Lake City 84112.
Biomed Sci Instrum. 1990;26:161-5.
A technique has been developed for fabricating three dimensional "hair brush" electrode arrays from monocrystalline silicon blocks. Arrays consist of a square pattern of 100 penetrating electrodes, with 400 microns interelectrode spacing. Each electrode is 1.5mm in length and tapers from about 100 microns at its base to a sharp point at the tip. The tips of each electrode are coated with platinum and the entire structure, with the exception of the tips, is insulated with polyimide. Electrical connection to selected electrodes is made by wire bonding polyimide insulated 25 microns diameter gold lead wires to bonding pads on the rear surface of the array. As the geometrical characteristics of the electrodes in such an aray will influence their electrical properties (such as impedance, capacitance, spreading resistance in an electrolyte, etc.) it is desirable that such an array have minimal variability in geometry from electrode to electrode. A study was performed to determine the geometrical variability resulting from our micromachining techniques. Measurements of the diameter of each of the 100 electrodes were made at various planes above the silicon substrate of the array. For the array that was measured, the standard deviation of the diameters was approximately 9% of the mean diameter near the tip, 8% near the middle, and 6% near the base. We describe fabrication techniques which should further reduce these variabilities.
已开发出一种从单晶硅块制造三维“毛刷”电极阵列的技术。阵列由100个穿透电极的方形图案组成，电极间距为400微米。每个电极长度为1.5毫米，从底部约100微米逐渐变细至尖端的尖锐点。每个电极的尖端涂有铂，除尖端外，整个结构用聚酰亚胺绝缘。通过将聚酰亚胺绝缘的直径为25微米的金线引线键合到阵列背面的键合焊盘上，实现与选定电极的电连接。由于这种阵列中电极的几何特性会影响其电学性能（如阻抗、电容、电解质中的扩展电阻等），因此希望这种阵列中电极之间的几何变化最小。进行了一项研究以确定我们的微加工技术导致的几何变化。在阵列的硅基板上方的各个平面上测量了100个电极中每个电极的直径。对于测量的阵列，直径的标准偏差在尖端附近约为平均直径的9%，在中间附近为8%，在底部附近为6%。我们描述了应进一步降低这些变化的制造技术。
