Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
Department of Chemistry, University of California at Berkeley, Berkeley, California, USA.
Sci Rep. 2017 Mar 7;7:43994. doi: 10.1038/srep43994.
Low thermal-equilibrium nuclear spin polarizations and the need for sophisticated instrumentation render conventional nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) incompatible with small-scale microfluidic devices. Hyperpolarized Xe gas has found use in the study of many materials but has required very large and expensive instrumentation. Recently a microfabricated device with modest instrumentation demonstrated all-optical hyperpolarization and detection of Xe gas. This device was limited by Xe polarizations less than 1%, Xe NMR signals smaller than 20 nT, and transport of hyperpolarized Xe over millimeter lengths. Higher polarizations, versatile detection schemes, and flow of Xe over larger distances are desirable for wider applications. Here we demonstrate an ultra-sensitive microfabricated platform that achieves Xe polarizations reaching 7%, NMR signals exceeding 1 μT, lifetimes up to 6 s, and simultaneous two-mode detection, consisting of a high-sensitivity in situ channel with signal-to-noise of 10 and a lower-sensitivity ex situ detection channel which may be useful in a wider variety of conditions. Xe is hyperpolarized and detected in locations more than 1 cm apart. Our versatile device is an optimal platform for microfluidic magnetic resonance in particular, but equally attractive for wider nuclear spin applications benefitting from ultra-sensitive detection, long coherences, and simple instrumentation.
低热平衡核自旋极化和对复杂仪器的需求使得传统的磁共振（NMR）光谱和成像（MRI）与小规模微流控装置不兼容。超极化氙气已在许多材料的研究中得到应用，但需要非常大且昂贵的仪器。最近，一种具有适度仪器的微制造设备演示了氙气的全光学极化和检测。该设备受到小于 1%的氙极化、小于 20nT 的氙 NMR 信号以及毫米长度的超极化氙传输的限制。更高的极化、多功能的检测方案以及更大距离的氙气流动是更广泛应用所需要的。在这里，我们展示了一种超灵敏的微制造平台，该平台实现了氙极化达到 7%、NMR 信号超过 1μT、寿命长达 6s 以及同时进行两种模式检测，包括具有 10 的信噪比的高灵敏度原位通道和较低灵敏度的场外检测通道，该通道在更广泛的条件下可能很有用。氙气在相隔超过 1cm 的位置进行超极化和检测。我们的多功能设备是微流控磁共振的理想平台，特别是对于超灵敏检测、长相干时间和简单仪器的更广泛的核自旋应用同样具有吸引力。
