Lin Wenyu, Wei Wei, Wu Jun, Cao Qing, Bi Hailin, Zhang Jun, Mei Zhengwei, Jin Jian, Wang Xudi
School of Mechanical Engineering, Hefei University of Technology, Hefei, 230009, China.
Institute of Advanced Science Facilities, Shenzhen, 518107, China.
Anal Chim Acta. 2023 Oct 16;1278:341690. doi: 10.1016/j.aca.2023.341690. Epub 2023 Aug 7.
As one of the primary residual gases in vacuum, hydrogen affects the performance of MEMS devices. It commonly uses a non-evaporable getter (NEG) to adsorb hydrogen in this case. One of the standard test methods for NEG is the constant pressure method. However, most constant pressure test systems control the intake flow by valves or small orifices. These methods are crude and limit the reliability of the result. Therefore, it is necessary to provide a stable intake flow method for the constant pressure test system to improve the accuracy of the test.
We demonstrate a constant pressure system based on the microfluidic chip flowmeter to evaluate the hydrogen adsorption performance of non-evaporable getters in this paper. The microfluidic chip features microchannels with a height of around 100 nm. It is encapsulated with standard tube fittings, with leakage of less than 1 × 10 Pa ∙ m∙ s. The conductance of the flowmeter is 10 m∙ s, and the upper-pressure limit of the molecular flow is 10 Pa. It can control the intake flow of the adapted constant pressure test system from 10 to 10 Pa ∙ m∙ s. Using this system, we tested the hydrogen adsorption capability of the Zr-Fe getter at different working pressures/temperatures and the types of gas it adsorbs were analysed. The results showed that the adsorbent has a noticeable adsorption effect on H and a partial adsorption effect on HO, CO and CO.
The microfluidic chip flowmeter can provide a stable intake molecular flow for the adapted constant pressure test system. It ensures the reliability of the measurement results. The ability of the flowmeter to offer tiny flow rates at 10 Pa can drastically simplify the test system and is more user-friendly for getters tests with poor adsorption performance. It has positive significance for industrial research on the non-evaporable getter.
作为真空中的主要残余气体之一，氢气会影响微机电系统（MEMS）器件的性能。在这种情况下，通常使用非蒸散型吸气剂（NEG）来吸附氢气。NEG的标准测试方法之一是恒压法。然而，大多数恒压测试系统通过阀门或小孔来控制进气流量。这些方法较为粗糙，限制了测试结果的可靠性。因此，有必要为恒压测试系统提供一种稳定的进气流量方法，以提高测试的准确性。
本文展示了一种基于微流控芯片流量计的恒压系统，用于评估非蒸散型吸气剂的氢吸附性能。该微流控芯片具有高度约为100纳米的微通道。它采用标准管件封装，泄漏率小于1×10 帕·米·秒。流量计的电导率为10 米·秒，分子流的上限压力为10 帕。它可以将适配的恒压测试系统的进气流量控制在10至10 帕·米·秒之间。使用该系统，我们测试了Zr-Fe吸气剂在不同工作压力/温度下的氢吸附能力，并分析了其吸附的气体种类。结果表明，该吸附剂对H有明显的吸附效果，对HO、CO和CO有部分吸附效果。
微流控芯片流量计可为适配的恒压测试系统提供稳定的进气分子流。它确保了测量结果的可靠性。该流量计在10 帕下提供微小流量的能力可大幅简化测试系统，对于吸附性能较差的吸气剂测试而言对用户更友好。它对非蒸散型吸气剂的工业研究具有积极意义。
