UNS: Fast Focus-scanning Microscopy Using Micron-thick phase Plates Based on High-index Meta-structures

了解大脑是如何工作的是这一代人面临的主要科学挑战之一。用于神经成像、激发和记录的光学技术在解构神经回路中起着至关重要的作用。来自神经元组的光学调制和记录是通过光遗传学和遗传编码的电压传感器实现的。为了充分利用这一能力，PI建议开发一种快速而纤薄的设备，能够以比动作电位更快的速度和比神经元细胞体更小的空间分辨率将光聚焦在与皮质柱相同数量级的体积中。使能技术是最近发明的电介质超表面，结构比波长更薄，允许对自由空间传播光进行前所未有的控制。该技术的独特之处在于能够将相位板光刻放置在非常接近的位置（数十微米），并使用静电力以高速驱动它们，如在微机电设备（MEMS）中。如果成功的话，这个项目将使设备可以扫描许多神经元在一个皮层柱与单一的动作电位时间分辨率，从而导致解构的神经回路在该列。这个跨学科的项目将提供机会，培养研究生在纳米光子学和生物显微镜。学生将模拟和制造设备，将开发一个复杂的显微镜设置，并将对大脑样本进行双光子显微镜测量。除了研究生教育，本科生将通过加州理工学院的SURF计划为该项目做出贡献。PI和研究生将参与纳瓦霍预备高中的外展活动，纳瓦霍预备高中是一所位于新墨西哥州法明顿的美国土著高中。该活动将包括前往法明顿教授科学课程，描述研究，并为访问加州理工学院的高中生设置演示。

AbstractFaraon1512266Understanding how the brain works is one of the main scientific challenges of this generation. Optical techniques for neural imaging, excitation and recording play a crucial role in deconstructing the neural circuitry. Optical modulation and recording from sets of neurons is enabled by optogenetics and genetically encoded voltage sensors. To fully use this capability, the PI proposes to develop a fast and slim device capable of focusing light in a volume on the same order of magnitude as a cortical column at speeds faster than an action potential and spatial resolution smaller than a neuronal cell body. The enabling technology is the recent invention of dielectric meta-surfaces, structures thinner than a wavelength that allow for unprecedented control of free-space propagating light. The uniqueness of the technology stems from the capability to lithographically place the phase plates in very close proximity (tens of microns) and to actuate them at high speeds using electrostatic forces like in micro electro-mechanical devices (MEMS). If successful, this project will enable devices that could scan many neurons in a cortical column with single action potential temporal resolution, thus resulting in deconstruction of neural circuitry in that column.This interdisciplinary project will provide the opportunity to train a graduate student in nano-photonics and biomicroscopy. The student will simulate and fabricate the devices, will develop a complex microscope setup, and will do two-photon microscopy measurements on brain samples. In addition to graduate student education, undergraduate students will contribute to the project through the SURF program at Caltech. The PI and the graduate student will be involved in an outreach activity with the Navajo Preparatory High School, a native American high school located in Farmington, New Mexico. The activity will consist in travelling to Farmington to teach science lessons, describing the research, and setting up demonstrations for high school students visiting Caltech.