Spengler Nils, Höfflin Jens, Moazenzadeh Ali, Mager Dario, MacKinnon Neil, Badilita Vlad, Wallrabe Ulrike, Korvink Jan G
Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany.
Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany.
PLoS One. 2016 Jan 5;11(1):e0146384. doi: 10.1371/journal.pone.0146384. eCollection 2016.
We present a completely revised generation of a modular micro-NMR detector, featuring an active sample volume of ∼ 100 nL, and an improvement of 87% in probe efficiency. The detector is capable of rapidly screening different samples using exchangeable, application-specific, MEMS-fabricated, microfluidic sample containers. In contrast to our previous design, the sample holder chips can be simply sealed with adhesive tape, with excellent adhesion due to the smooth surfaces surrounding the fluidic ports, and so withstand pressures of ∼2.5 bar, while simultaneously enabling high spectral resolution up to 0.62 Hz for H2O, due to its optimised geometry. We have additionally reworked the coil design and fabrication processes, replacing liquid photoresists by dry film stock, whose final thickness does not depend on accurate volume dispensing or precise levelling during curing. We further introduced mechanical alignment structures to avoid time-intensive optical alignment of the chip stacks during assembly, while we exchanged the laser-cut, PMMA spacers by diced glass spacers, which are not susceptible to melting during cutting. Doing so led to an overall simplification of the entire fabrication chain, while simultaneously increasing the yield, due to an improved uniformity of thickness of the individual layers, and in addition, due to more accurate vertical positioning of the wirebonded coils, now delimited by a post base plateau. We demonstrate the capability of the design by acquiring a 1H spectrum of ∼ 11 nmol sucrose dissolved in D2O, where we achieved a linewidth of 1.25 Hz for the TSP reference peak. Chemical shift imaging experiments were further recorded from voxel volumes of only ∼ 1.5 nL, which corresponded to amounts of just 1.5 nmol per voxel for a 1 M concentration. To extend the micro-detector to other nuclei of interest, we have implemented a trap circuit, enabling heteronuclear spectroscopy, demonstrated by two 1H/13C 2D HSQC experiments.
我们展示了全新一代经过全面修订的模块化微型核磁共振探测器，其有效样品体积约为100纳升，探头效率提高了87%。该探测器能够使用可互换的、特定应用的、微机电系统制造的微流控样品容器快速筛选不同样品。与我们之前的设计相比，样品 holder 芯片可以简单地用胶带密封，由于流体端口周围表面光滑，具有出色的附着力，因此能够承受约2.5巴的压力，同时由于其优化的几何形状，对于H2O能够实现高达0.62赫兹的高光谱分辨率。我们还重新设计了线圈设计和制造工艺，用干膜材料取代了液体光刻胶，其最终厚度不依赖于固化过程中的精确体积分配或精确平整。我们进一步引入了机械对准结构，以避免组装过程中芯片堆栈进行耗时的光学对准，同时我们将激光切割的聚甲基丙烯酸甲酯垫片换成了切割玻璃垫片，后者在切割过程中不易熔化。这样做使得整个制造流程得到了全面简化，同时由于各层厚度均匀性的提高以及引线键合线圈更精确的垂直定位（现在由柱基平台界定），产量也得以提高。我们通过获取溶解在D2O中的约11纳摩尔蔗糖的1H谱图来展示该设计的能力，其中我们获得了TSP参考峰1.25赫兹的线宽。化学位移成像实验进一步从仅约1.5纳升的体素体积中记录，对于1M浓度，这相当于每个体素仅1.5纳摩尔的量。为了将微型探测器扩展到其他感兴趣的原子核，我们实施了一个陷波电路，实现了异核光谱，通过两个1H/13C二维HSQC实验得到了证明。
