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。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。光遗传学和基因编码电压传感器使神经元的光调制和记录成为可能。为了充分利用这一能力，PI建议开发一种快速而轻薄的设备，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聚焦与皮质柱相同数量级的光。使之成为可能的技术是最近发明的介电元表面，这种结构比波长更薄，可以前所未有地控制自由空间传播的光。该技术的独特之处在于，它能够以光刻技术将相板放置在非常接近的位置（几十微米），并像微机电设备（MEMS）一样使用静电力以高速驱动它们。如果成功，该项目将使设备能够扫描皮层柱中的许多神经元，具有单一动作电位的时间分辨率，从而导致该柱中的神经回路的解构。这个跨学科的项目将为培养纳米光子学和生物显微学的研究生提供机会。学生将模拟和制造这些设备，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。除了研究生教育外，本科生将通过加州理工学院的SURF项目为该项目做出贡献。PI和研究生将参与纳瓦霍预备高中的外展活动，这是一所位于新墨西哥州法明顿的美国本土高中。该活动将包括前往法明顿教授科学课程，描述研究，并为参观加州理工学院的高中生进行演示。

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.