SUBMINIATURE MAGNETIC FIELD SURVEY PROBE SYSTEM FOR ESR MICROSCOPY

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 尽管ESR显微成像中采用的磁场梯度的有效性与所采用的成像序列密切相关，但实现尽可能强的和几何上强的梯度仍然很重要。对于16 GHz的显微成像工作，我们已经证明了峰值为~ 26 T/m的相位梯度，这对应于~3 μ m的分辨率。在35 GHz时，成像探头及其组成部件将更小，梯度线圈将获得超过40 T/m的峰值，这是1 μ m分辨率所需的。尽管梯度效率随着探头和线圈尺寸的减小而增加，但保持几何精度的问题将成比例地放大。同样明显的是，在16 GHz和35 GHz的梯度线圈开发的主题中，梯度效率的进一步优化可以实现甚至更高的分辨率。我们的梯度线圈设计方法将是模拟和经验测试的结合。 出于这些原因，我们已经启动了一个程序，以实现为微成像探头设计的单个线圈和组装梯度线圈组的高分辨率映射。我们目前的调查是微型霍尔器件的可行性微米分辨率场映射。我们已经获得了合适的~ 1 mm霍尔传感器，具有足够的灵敏度，并且正在设计适合于测试线圈场映射的平移平台。预计这一映射组件将以初始形式组装，并在2008年秋季使用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Although the effectiveness of the magnetic field gradients employed in ESR microimaging is closely related to the imaging sequence employed, it is nonetheless important to achieve as intense and geometrically intense gradients as possible. For microimaging work at 16GHz, we have already demonstrated phase gradients with peak values of ~26T/m, which corresponds to ~3 ¿m resolution. At 35GHz the imaging probe and its constituent components will be even smaller and the gradient coils will obtain peak values of more than 40T/m, required for 1 ¿m resolution. Although the gradient efficiency increases as the probe and coil size decreases, the problem of maintaining geometric accuracy will be proportionally magnified. It is also evident that, in the topic of gradient coils development at both 16GHz and 35GHz, further optimization of the gradient efficiency may enable even higher resolution. Our approach to gradient coil design will be a combination of simulation and empirical testing. For these reasons, we have initiated a program to enable high resolution mapping of individual coils and assembled gradient coil sets which have been designed for the microimaging probes. Our current investigation is the viability of subminiature Hall devices for micron-resolution field mapping. We have obtained suitable ~1mm Hall sensors of adequate sensitivity and are in the process of designing a translation platform suitable for field mapping of the test coils. This mapping assembly is expected to be assembled in an initial form and usable during fall 2008.