Nanofluidic system with electrochemical and flow mixing capabilities for in-liquid electron microscopy studies - Phase I

为了实现透射电子显微镜（TEM）和电子衍射/散射（TED）测量，对纳米级甚至可能低至原子级的液体样品的研究需要将非常专业的纳米流体电池系统（NFCS）集成到电子显微镜中。因此，NFCS是一种高科技设备（或TEM配件），能够操纵并将微量液体输送到电子束路径进行观察。纳米流控柱包括纳米流控池（NFC）和纳米流控支架（NFCHs），它们相互密封以防止液体泄漏并保持电子显微镜柱内的真空完整性。nfcs的设计在概念上很简单；然而，实现对液体流动的真正控制，以及在一定程度上达到NFC可视窗口上液体层的厚度，仍然是当前NFCS制造商面临的一个未解决的挑战。由于电子与物质的强烈相互作用，需要以极薄的氮化硅薄膜（10nm - 100nm）为窗口实现极短的电子束（通常在100nm - 1000nm之间）。虽然毛细管力最初可能会有帮助，但纳米通道截面积的减小会产生很大的流动阻力，从而在入口形成压力。尽管它们的成本非常高，但商业上最先进的nfcs的设计过于简单，无法确保真正的液体流动；也就是说，液体流过纳米通道的阻力非常大，以至于大部分液体会绕着NFC三明治流动，而任何强迫液体路径的努力都会导致窗口膨胀和图像质量恶化。UW纳米流体技术规避了上述问题，实现了对液体流速的真正控制，结合流体混合和原位电化学能力，将允许实现新的和令人兴奋的原位TEM实验。预计将在滑铁卢地区成立一家初创企业（约2020年秋季）。

The study of in-liquid samples with nanometre and potentially down to atomic resolution requires the integration of a very specialized nanofluidic cell system (NFCS) into the electron microscope in order to enable transmission electron microscopy (TEM) and electron diffraction/scattering (TED) measurements. A NFCS is therefore a high-tech device (or TEM accessory) capable of manipulating and delivering tiny amounts of liquid to the electron beam path for observation. The NFCS comprises and a nanofluidic cell (NFC) and a nanofluidic holder (NFCHs), which are mutually sealed to prevent liquid leaks and preserve the vacuum integrity inside the electron microscope column. The designs of NFCSs are conceptually simple; however, achieving true control of the liquid flow, and up to some extend of the thickness of the liquid layer across the viewing windows of the NFC continues to be an unsolved challenge for current NFCS manufacturers. The strongly interacting nature of electrons with matter leads to the necessity of implementing a very short electron beam (often within 100 nm - 1000 nm) with very thin silicon nitride films (10 nm - 100 nm) as windows. Although capillary forces may initially help, the reduced cross-sectional area of the nanochannel creates a large resistance to flow and with that pressure builds up in the inlet. Despite their very high cost, the design of commercial state-of-the-art NFCSs is way too simple to ensure true liquid flow; i.e. the resistance for liquid to flow through the nanochannel is so large that most of the fluid goes around the NFC sandwich while any effort to force the liquid path would lead to window bulging and the deterioration of image quality. UW nanofluidic technology circumvented the aforementioned issues, enabling true control of the liquid flow rate, which in combination with fluid mixing and in situ electrochemistry capabilities will allow for realization of new and exciting in situ TEM experiments. The creation of a start-up in Waterloo region is anticipated (ca. fall 2020).