Eindhoven University of Technology, Applied Physics Department, P.O. Box 513, Eindhoven, 5600 MB, the Netherlands; Transport in Permeable Media group, Department of Applied Physics, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, the Netherlands.
Eindhoven University of Technology, Applied Physics Department, P.O. Box 513, Eindhoven, 5600 MB, the Netherlands; Transport in Permeable Media group, Department of Applied Physics, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, the Netherlands; TNO Materials Solution, High Tech Campus 25, Eindhoven, the Netherlands.
Magn Reson Imaging. 2023 Nov;103:61-74. doi: 10.1016/j.mri.2023.06.009. Epub 2023 Jun 20.
Measuring moisture distributions during fast transport processes in thin porous media is a challenging task. In this paper, Ultra Fast Imaging (UFI) NMR is proposed as a valuable measurement technique for investigating moisture uptake in porous media by achieving a temporal resolution of 10 ms and spatial resolution between 14.5 and 18 μm. This paper gives a detailed explanation about the methodology and the interpretation of the signal intensity. It is shown that there exist specific T- and T- relaxation time conditions for performing UFI experiments with signal-to-noise ratios that are sufficiently high. In most cases, a contrast agent is required to optimize these relaxation times and achieve the optimal measurement conditions. In the first part of this paper, both CuSO4 and Clariscan are discussed as possible contrast agents. Furthermore, it is shown that the signal intensity can be linked to the moisture content for water based liquids. The second part of this paper covers penetration experiments on porous PVDF membranes. These measurements show that the technique is able to measure moisture profiles during fast capillary penetration and allows to extract moisture front positions. Those front positions follow a linear time behavior in PVDF membranes. Lastly the NMR-measurements showed similar results when compared to scanning absorptometry (ASA).
在薄的多孔介质中快速传输过程中测量水分分布是一项具有挑战性的任务。在本文中，超快成像（UFI）NMR 被提出作为一种有价值的测量技术，通过实现 10ms 的时间分辨率和 14.5 到 18μm 之间的空间分辨率来研究多孔介质中的水分吸收。本文详细解释了该方法以及信号强度的解释。结果表明，在存在特定的 T 和 T 弛豫时间条件下，可以进行具有足够高信噪比的 UFI 实验。在大多数情况下，需要使用对比剂来优化这些弛豫时间并实现最佳测量条件。在本文的第一部分，讨论了 CuSO4 和 Clariscan 作为可能的对比剂。此外，结果表明，信号强度可以与水基液体的水分含量相关联。本文的第二部分涵盖了多孔 PVDF 膜的渗透实验。这些测量表明，该技术能够在快速毛细管渗透过程中测量水分分布，并能够提取水分前沿位置。在 PVDF 膜中，这些前沿位置遵循线性时间行为。最后，与扫描吸收法（ASA）相比，NMR 测量显示出相似的结果。
