Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands.
Nanotechnology. 2010 Mar 19;21(11):115304. doi: 10.1088/0957-4484/21/11/115304. Epub 2010 Feb 22.
Solid-state nanopores are considered a promising tool for the study of biological polymers such as DNA and RNA, due largely to their flexibility in size, potential in device integration and robustness. Here, we show that the precise shape of small nanopores (approximately 5 nm diameter in 20 nm SiN membranes) can be controlled by using transmission electron microscope (TEM) beams of different sizes. However, when some of these small nanopores are immersed in an aqueous solution, their resistance is observed to decrease over time. By comparing nanopores of different shapes using (scanning) TEM both before and after immersion in aqueous solution, we demonstrate that the stability of small nanopores is related to their three-dimensional geometry, which depends on the TEM beam size employed during pore fabrication. Optimal stability is obtained using a TEM beam size of approximately the same size as the intended nanopore diameter. In addition, we show that thermal oxidation can serve as a means to independently control nanopore size following TEM fabrication. These observations provide key guidelines for the fabrication of stable solid-state nanopores on the scale of nucleic acids and small proteins.
固态纳米孔被认为是研究生物聚合物（如 DNA 和 RNA）的一种很有前途的工具，这主要是因为它们在尺寸、器件集成潜力和鲁棒性方面具有灵活性。在这里，我们展示了可以通过使用不同尺寸的透射电子显微镜（TEM）光束来控制小纳米孔（20nm SiN 膜中约 5nm 直径）的精确形状。然而，当这些小孔中的一些浸入水溶液中时，它们的电阻会随时间而降低。通过比较浸入水溶液前后不同形状的纳米孔（使用（扫描）TEM），我们证明了小纳米孔的稳定性与其三维几何形状有关，这取决于在孔制造过程中使用的 TEM 光束尺寸。使用尺寸与预期纳米孔直径大致相同的 TEM 光束可获得最佳稳定性。此外，我们还表明，热氧化可以作为一种在 TEM 制造后独立控制纳米孔尺寸的手段。这些观察结果为在核酸和小蛋白质尺度上制造稳定的固态纳米孔提供了关键指导。
