Graphene containing intrinsic pores with molecular dimensions is a highly promising material for standard leak elements because of its minimal and stable gas flow. However, the etching of polymethyl methacrylate (PMMA) during the typical graphene transfer process can cause the rupture of graphene on the porous substrate due to the surface tension as the etchant solution dries out. In this article, we simplified the typical graphene transfer process that enabled the transfer of a PMMA/graphene composite membrane onto a macroporous Cu gasket as the leak element and tested the leak rate, time stability, and response time of the composite membrane. The membrane permeation area depends on the pore size of the Cu substrate, which can be controlled by laser ablation or computer numerical control milling. To ensure the accuracy of time stability, the entire test lasted 60 days. The conductance results for two devices with a permeation size of 50 and 500 μm were about 10⁻¹⁷ and 10⁻¹⁴ m³ s⁻¹, and the maximum variation of conductance in 60 days was 14% and 2.6%, respectively. Accordingly, the permeance of the composite membrane for helium can be calculated as 4.17 × 10⁻¹²–1.09 × 10⁻¹¹ Pa m³ (cm² s Pa)⁻¹. Moreover, the composite membrane has been proven to have a rapid response of about 2 s to the upstream pressure.

中文翻译：

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基于单层石墨烯复合膜的新型氦气泄漏元件

含有分子尺寸的固有孔的石墨烯由于其最小且稳定的气体流动而成为用于标准泄漏元件的非常有前途的材料。然而，在典型的石墨烯转移过程中对聚甲基丙烯酸甲酯 (PMMA) 的蚀刻会由于蚀刻剂溶液变干时的表面张力而导致多孔基板上的石墨烯破裂。在本文中，我们简化了典型的石墨烯转移过程，该过程能够将 PMMA/石墨烯复合膜转移到作为泄漏元件的大孔 Cu 垫片上，并测试了复合膜的泄漏率、时间稳定性和响应时间。膜渗透面积取决于铜基板的孔径，可以通过激光烧蚀或计算机数控铣削来控制。为保证时间稳定性的准确性，整个测试持续了60天。渗透尺寸为 50 和 500 的两个器件的电导结果 μ m 约为10 ^-17和10 ^-14  m ³  s ^-1，60天内电导的最大变化分别为14%和2.6%。因此，复合膜的氦气渗透率可以计算为4.17 × 10 ^-12 –1.09 × 10 ^-11  Pa m ³ (cm ²  s Pa) ^-1。此外，复合膜已被证明对上游压力具有约 2 秒的快速响应。