HFSS Modeling in Aqueous Biological Samples for EPR

描述(由申请人提供)：本提案以设备设计为导向。这项拟议工作的目标是提高水相流体样品的电子顺磁共振(EPR)光谱的灵敏度。有两个主题：(1)从1 GHz到35 GHz的多频增强；(2)针对有限可获得性(约1微升)、中等可获得性(约10-20微升)和无限可获得性(&gt；100微升)的样品进行优化。这一目标将通过优化微波谐振器设计和优化水样池设计来实现。这项提议是及时的，因为最近电磁场有限元建模软件的进步，加上计算速度的极大提高。谐振器、样品池和场调制线圈将使用计算机辅助设计，随后将进行实验评估。具体目标有五个：(1)环隙谐振器的水样。这并不是以前任何出版物的主要主题。(2)适用于水溶液样品的均匀场谐振器。这种创新的谐振器在PI实验室最近的三篇论文中介绍和开发，并发表在《科学仪器评论》上，当有更大数量的样品可用时，它具有很大的前景。(3)几种类型的水样细胞团的评价。在最近推出的一种商业产品中已经发现，样品细胞簇可以捆绑在一起，在实际应用中是有用的。这一概念尚未成为任何出版物的主题，存在一些进一步加强的机会。(4)用于水溶液样品的再入腔谐振器。这个设计很有创意。这种方法允许针对特定应用优化谐振器。这里提出的一种方法是在L波段进行小鼠体内电子顺磁共振成像。(5)场调制数值优化。以前还没有关于有限元建模用于此目的的报道。电子顺磁共振波谱是生物医学研究中的一种重要手段。通过自旋捕获检测到的短寿命自由基的研究，使用定点定向自旋标记的分子结构的研究，使用自旋探针的生物膜或模型膜的研究，以及细胞或组织制剂的研究通常在水环境中进行。这里提出的工作将提高在这些实验中获得的数据的质量。均匀场谐振器还提供了一个额外的好处。因为微波场在样品上是均匀的，所以所有部分都以相同的方式响应，这提高了数据质量。

DESCRIPTION (provided by applicant): This proposal is device design driven. The goal of the proposed work is to improve sensitivity in electron paramagnetic resonance (EPR) spectroscopy of aqueous fluid phase samples. There are two themes: (i) multifrequency enhancement from 1 to 35 GHz, and (ii) optimization for samples of limited availability (ca., 1 microliter), intermediate availability (ca., 10-20 microliters) and unlimited availability (>100 microliters). This goal will be achieved by optimization of microwave resonator design and by optimization of aqueous sample cell design. The proposal is timely because of recent advances in software for finite element modeling of electromagnetic fields, coupled with greatly improved computing speeds. Computer aided design will be used for resonators, sample cells and field modulation coils, followed by experimental evaluation. There are five Specific Aims: (1) Aqueous samples for loop gap resonators. This has not been the primary subject of any previous publication. (2) Uniform Field resonators for aqueous samples. This innovative class of resonators, introduced and developed in three recent papers from the PI's laboratory and published in the Review of Scientific Instruments, holds great promise when larger amounts of sample are available. (3) Evaluation of several types of aqueous sample cell clusters. It has been found in a recently introduced commercial product that clusters of sample cells can be bundled together and are useful in practical applications. The concept has not been the subject of any publication and a number of opportunities exist for further enhancement. (4) Re-entrant cavity resonators for aqueous samples. The design is innovative. This approach permits optimization of resonators for specific applications. One proposed here is for murine in vivo EPR imaging at L-band. (5) Field modulation numeric optimization. No previous use of finite element modeling has been reported for this purpose. EPR spectroscopy is an important modality in biomedical research. Studies of short-lived radicals detected by spin trapping, of molecular structure using site directed spin labeling, of biological or model membranes using spin probes, and of cell or tissue preparations are usually carried out in an aqueous environment. Work proposed here will improve the quality of data obtained in these experiments. An additional benefit is provided by Uniform Field resonators. Because the microwave field is uniform over the sample, all portions respond in the same way, which improves the data quality.