Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States.
Office of Research and Innovation, The University of Texas at Dallas, Richardson, Texas 75080, United States.
ACS Appl Mater Interfaces. 2024 Nov 13;16(45):61621-61632. doi: 10.1021/acsami.4c11773. Epub 2024 Oct 30.
The design and characterization of thin-film ribbon cables as electrical interconnects for implanted neural stimulation and recording devices are reported. Our goal is to develop flexible and extensible ribbon cables that integrate with thin-film, cortical penetrating microelectrode arrays (MEAs). Amorphous silicon carbide (a-SiC) and polyimide were employed as the structural elements of the ribbon cables and multilayer titanium/gold thin films as electrical traces. Using photolithography and thin-film processing, ribbon cables with linear and serpentine electrical traces were investigated. A cable design with an open lattice geometry was also investigated as a means of achieving high levels of extensibility while preserving the electrical function of the cables. Multichannel ribbon cables were fabricated with 50 mm lengths and metallization trace widths of 2-12 μm. The ribbon cables tolerate flexural bending to a radius of 50 μm with no change in trace impedance but tolerate less than 5% tensile elongation without trace failure. Ribbon cables with a lattice structure exhibit 300% elongation without failure. The high elongation tolerance is attributed to a lattice design that results in an out-of-plane displacement that avoids fracture or plastic deformation. Extensible ribbon cables underwent up to 50,000 tensile elongation cycles to 45% extension without failure. An electrical interconnect process using through-holes in the distal gold bond pads of the ribbon cables was used to connect to an a-SiC-based MEA. The electrical connection was created by stenciling a conductive epoxy into the through-holes, bridging metallization between the traces, and MEA. The interconnect was tested using a ribbon cable connected to an a-SiC MEA implanted acutely in rat cortex and used to record neuronal activity. These highly flexible and extensible ribbon cables are expected to accommodate large extensions and facilitate cable routing during surgical implantation. They may also reduce tethering forces on implanted electrode arrays, potentially improving chronic neural recording performance.
报告了作为植入式神经刺激和记录装置电互连的薄膜带状电缆的设计和特性。我们的目标是开发与薄膜、皮质穿透微电极阵列 (MEA) 集成的柔性和可扩展的带状电缆。非晶硅碳化硅 (a-SiC) 和聚酰亚胺被用作带状电缆的结构元件，多层钛/金薄膜用作电迹线。使用光刻和薄膜处理技术，研究了具有线性和蛇形电迹线的带状电缆。还研究了具有开放晶格几何形状的电缆设计，作为实现高水平可扩展性的一种手段，同时保持电缆的电功能。制造了具有 50mm 长度和 2-12μm 金属化迹线宽度的多通道带状电缆。带状电缆可以弯曲到 50μm 的半径而不会改变迹线阻抗，但在没有迹线故障的情况下，只能承受小于 5%的拉伸伸长率。具有晶格结构的带状电缆在不失效的情况下可实现 300%的伸长率。高伸长率容差归因于晶格设计，该设计导致平面外位移，从而避免了断裂或塑性变形。可扩展的带状电缆在经受高达 50,000 次拉伸循环至 45%的拉伸伸长率而不会失效。使用带状电缆远端金键合垫中的通孔的电互连工艺用于连接基于 a-SiC 的 MEA。通过将导电环氧树脂模板印刷到通孔中、在迹线和 MEA 之间桥接金属化来创建电气连接。使用连接到在大鼠皮层中急性植入的 a-SiC MEA 的带状电缆对互连进行了测试，并用于记录神经元活动。这些高度灵活和可扩展的带状电缆有望适应大的扩展并在手术植入过程中便于电缆布线。它们还可能减少植入式电极阵列的系绳力，从而有可能提高慢性神经记录性能。
