Silicon nanoporous membranes provide the fundamental underlying technology for the development of an implantable bio-artificial kidney. These membranes, which are comprised of micromachined slit-pores that are nominally 10 nm wide, allow for high-efficiency blood filtration as well as immunoprotection for encapsulated cells. Our approach takes advantage of well-established semiconductor fabrication technology to give us precise dimensional control over pore widths, thereby enabling a highly selective filtration function and a clear path towards further miniaturization. This work builds on our prior results on “ribbed nanoporous membranes” by adding a second-level hierarchy of significantly taller “mega-ribs” to further strengthen the membranes. Relying on a two-step Deep Reactive Ion Etch (DRIE) process, we etch 4 μm-deep as well as 40 μm-deep trenches into a silicon substrate, grow a thermal oxide liner, and deposit a layer of polysilicon into this “mold” to form membranes which, when released after a backside DRIE etch, feature a network of reinforcing ribs on the underside. We have fabricated and tested freestanding membrane spans that are up to 14 times wider than before, with approximately double the measured permeability per unit area. The new architecture can also improve cross-membrane mass-transfer rates and reduce chip-fabrication costs.

中文翻译：

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用于植入式生物人工肾的更大面积、更高孔隙率的纳米多孔膜的可扩展、分层肋设计


硅纳米多孔膜为可植入生物人工肾的开发提供了基础技术。这些膜由名义上宽 10 nm 的微机械狭缝孔组成，可实现高效血液过滤以及对封装细胞的免疫保护。我们的方法利用成熟的半导体制造技术，为我们提供对孔隙宽度的精确尺寸控制，从而实现高度选择性的过滤功能，并为进一步小型化开辟了清晰的道路。这项工作建立在我们之前关于“带肋纳米多孔膜”的结果的基础上，通过添加明显更高的“巨型肋”的二级层次结构来进一步增强膜。依靠两步深反应离子蚀刻 (DRIE) 工艺，我们在硅衬底上蚀刻 4 μm 深以及 40 μm 深的沟槽，生长热氧化物衬里，并在这个“模具”中沉积一层多晶硅。 ”以形成膜，该膜在背面 DRIE 蚀刻后释放时，在底部具有加强筋网络。我们制造并测试了独立式膜跨度，其宽度比以前宽达 14 倍，每单位面积的测量渗透率大约是测量的两倍。新架构还可以提高跨膜传质速率并降低芯片制造成本。