作者感激地感谢北卡罗来纳州立大学提供的财政支持。米拉德 Abolhasani 和罗伯特 w. 无害技术有限公司感激地承认从 unc 研究机会倡议 (unc ROI) 赠款的财政支持。

1. 反应堆总成
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57666/57666fig1.jpg"> 图 1.示例平台程序集过程的分步说明.这些面板显示了一个示例平台装配过程的分步演示, 详细介绍了 (i) 在安装面包宽上的平移阶段和光学后端的初始排列, (ii) 前置管安装阶段的安装和流单元到光学柱上, (iii) 将微流控管附着在具有透明度的自定义交叉路口上, 以显示流动通路, (iv) 在同时定位第一取样单元时, 确保前体油管的安全 (v)随后, 附加取样单位与反应堆油管的连接贯穿每个模块, (vi) 反应堆延伸单元的油管通路, (vii) 确保最后取样单元的安全, 以支持结构和光学哨所。<a href="/files/ftp_upload/57666/57666fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
注: 由于多种可能的配置, 微流控平台的精确装配过程可能会有所不同;然而, 所有安排的一般方法都是相同的。下面和图 1中详细说明了在 14th取样端口之后具有单个扩展单元的双前体、多相流格式的平台组装过程。
<ol><li>确保翻译阶段和开机自检者对光学案板。将接合安装阶段和流动单元连接到柱子上, 并将其固定在平台上。</li>
	<li>将反应堆油管和前体进给线连接到自定义交叉路口, 并通过所提阶段的通道给油管喂食。确保每个油管段被切割到一个长度, 可以舒适地达到各自的注射器泵或收集瓶。</li>
	<li>将第一取样端口单元连接到接合阶段, 并将前置线盖固定在凸起的安装阶段, 确保所有管状元件和第一取样单元就位。</li>
	<li>通过在所需组件上运行反应器油管, 并将各段连接到组装结构的其余部分, 添加额外的模块化反应器单元。从接合处建立单元, 直到得到所需的长度和排列。 注: 反应堆油管应牢固地安装在每个单元内。油管 (拉伸、压接等) 的变形对光信号强度有显著影响。</li>
	<li>将支撑结构固定在最后一个取样段的出口上, 并确保对连接到案板的光学柱的支持。</li>
	<li>将流系统的进给线与计算机控制的注射器泵连接, 并将反应器出口进氮气加压 (~ 12 psig) 收集瓶中。</li>
	<li>将3光纤贴线连接到3个流单元端口, 并将其两端分别连接到光谱仪、LED 和氘卤素 (DH) 光源。确保电缆能够顺利地与整个转换阶段的长度, 并没有任何不必要的应变与流单元的连接, 以完成平台组件 (如图 2所示)。</li>
</ol>2. 前体准备
注: 反应筛选系统可应用于各种胶体半导体纳米晶的合成;但是, 为了平台开发和验证, CsPbBr3钙钛矿合成, 从伟et . 中改编。6为了更好地适应流分析, 被用作案例研究反应。前体制备过程详述如下。
<ol><li>在密封的14毫升瓶中结合109毫克的四正辛基溴、1毫升油酸和20毫升甲苯, 制备15毫升0.013 米溴化物前驱体。</li>
	<li>在室温下用力搅拌混合物, 直到得到明确的溶液。</li>
	<li>先将氢氧化铯的0.6 毫摩尔、0.6 毫摩尔 (II) 氧化物和3毫升的油酸, 用隔膜在密封的8毫升瓶中, 制备48毫升0.0021 米的铯-铅前驱体。<ol>
<li>刺穿隔膜与针通风和加热溶液在160°c 在油浴, 并大力搅拌, 直到一个明确的解决方案 (约15分钟)。</li>
		<li>将瓶子和针头移到烤箱中, 加热120摄氏度1小时, 然后取出排气针, 让溶液在露天冷却到室温。</li>
	</ol>
</li>
	<li>在密封的50毫升瓶中加入0.5 毫升高浓度铯-铅混合物, 在47.5 毫升甲苯中搅拌。</li>
	<li>载入溴前驱体并将铯铅前驱体稀释到各自的注射器中, 并在所需的条件下将两个前驱体一起流动, 开始自动表征过程 (见步骤 3)。 注: 对于在代表性结果下详细说明的实验, 体积注入比为 6.4: 1 的铯-导致溴化物和1:1 的气载相到净液在可变总流速下使用。</li>
</ol>3. 接口操作
注: 整个数据收集是通过自动反应平台进行的, 用户指定一系列的流量条件进行测试。下面详细介绍了在初始输入期间操作用户界面的一般过程。
<ol><li>打开自动操作软件以查看用户界面前面板 (如图 3所示)。</li>
	<li>移动到光谱仪设置面板, 然后开始填充所有输入。<ol>
<li>将所需的数据保存文件夹的文件路径粘贴到数据的文件根框中。</li>
		<li>在光谱仪签证下, 选择光谱仪的 USB 连接地址。如果不知道光谱仪 USB 地址, 请通过桌面的设备管理器页标识其位置。</li>
		<li>选择集成时间、每个样本平均值的光谱数, 以及(吸收 (Abs)和荧光 (流感) 的每个条件保存的光谱数。在步骤2中详细说明的情况下, 将12毫秒的吸收时间和4毫秒的荧光平均值定为10光谱。</li>
		<li>如果描述单相流, 请继续执行下一步, 使多相按钮处于关闭状态。如果对多相流进行了描述, 请选择 "多相" 按钮并设置最小采样长度, 以便大约2个完整的气液振荡可以通过取样点。然后在该取样窗口中分配样本数。 注: 多相流中的采样时间分辨率可能受光谱仪设置的限制, 如果寻求更高的分辨率, 则可能需要进行调整。</li>
	</ol>
</li>
	<li>移动到泵配置面板, 然后开始填充所有输入。<ol>
<li>在注射器 1 com、注射器 2 com、和双泵 com 中,将 USB 通信地址分配给所有泵。有关地址标识过程, 请参见步骤3.2.2。</li>
		<li>设置在所使用的所有注射器上, 可在泵接口或注射器手册中找到的注射器内径。对于不实施所有注射器的配置, 请将多余的注射器直径留在缺省值上。</li>
		<li>如果收集吸收参考光谱, 确定一个可接受的空白解决方案, 将其加载到附加的注射器中, 并将相应的注射器设置为相应的Ref 流量框中的适度流速 (大约300µL/分钟)。</li>
	</ol>
</li>
	<li>移动到系统配置面板并开始填充所有输入。<ol>
<li>如果已优化舞台位置并在舞台位置下正确显示, 请选择使用上一位置按钮并移动到下一步。如果尚未优化舞台位置, 请使用. csv 向量和文件路径框指定舞台位置窗口大小, 并将大致阶段位置 (在位置范围内) 链接。将舞台递增框保留为0.5 毫米,启动刀路框为8。</li>
		<li>计算从连接中心到最终取样端口的反应堆段的体积, 并将该值输入到系统卷框中。在十年代保持最小平衡时间。</li>
	</ol>
</li>
	<li>双击所有输入的准确性, 然后在接口的左上选择Run按钮。 注意: 一旦软件开始运行, 前面板上的输入可能不会更改。</li>
	<li>在保存参考光谱窗口中, 如果引用光谱将被保存或No , 则选择是。</li>
	<li>在设置条件流速窗口中, 选择多达30个所需的流量配置进行测试, 将所有未使用的注射器输入留空。</li>
	<li>选择确定并允许系统运行, 直到取样所有所需的条件为止;系统自行关闭。如果由于任何原因需要停止系统, 请选择 "早期停止" 按钮, 并允许进程关闭。 警告: 使用接口左上的中止按钮将不允许系统关闭泵或光源, 可能会损坏设备和/或通过紫外线照射造成重大的健康风险。</li>
</ol>4. 光谱分析更正
<ol><li>为了获得每个端口的光谱分析校正相关性, 首先将 perovskites 分散在甲苯中的稳定溶液注入反应器段, 直到反应器管均匀填充为止。</li>
	<li>对此统一解决方案运行自动采样过程, 以实现流单元的4个完整传递 (请参见操作过程的步骤 3)。</li>
	<li>对荧光光谱和吸收光谱进行基线校正, 然后对通过端口位置的刀路进行平均总体。将参照波长强度的所有曲线正常化为 455 nm 和 485 nm, 分别用于吸收和荧光 (请参见图 4)。</li>
	<li>使用计算在每个端口的正常化系数, 以比例缩放所有后续光谱的曲线。</li>
</ol>

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北卡罗来纳州立大学在讨论的微流控平台上提交了一项临时专利 (#62/558155)。

自动取样系统:采用中央控制有限状态机进行屏蔽平台的自主运行。这些状态之间的移动依次与多个递归段一起进行, 以允许在不同的采样条件下进行操作。一般系统控制可分为3个核心阶段。首先, 系统从初始化步骤开始, 通过每个 USB 控制组件建立通信, 自动定义文件保存路径, 并提示输入初始用户。然后, 该程序在采样过程中对每个进入的反应条件运行, 直到收集到所有所需的数据为止。最后, 终止过程会在结束脚本操作之前将所有硬件返回到起始位置。此软件中的常规移动在图 6中详细说明。
端口检测:在主要的自动化框架内有几个关键的 subfunctions, 使有效和有效的反应刻画。首先,图 7显示了 "初始化" 部分的一部分, 其中为转换阶段定义了取样端口位置。端口检测功能首先通过模拟反应器上的流动单元运动来稳定反应堆段8个完整的刀路。然后, 它通过在估计位置周围的1毫米窗口取样荧光强度, 并选择最大强度的位置来检测最佳端口位置。此位置为每个端口保存, 并在后续取样过程中用作舞台位置。
光源切换:采用自动光源切换系统对三端口流单元内的有效吸光度和荧光光谱取样进行了设计。在到达取样端口时, 在15毫秒积分时间和荧光在4毫秒积分时间内的10种吸收光谱可在400毫秒内收集. 当在取样位置之间移动时, DH 灯和指示灯都将关闭。在到达所需取样端口时, 会触发 DH 灯, 并在光谱仪上设置吸光度取样条件, 然后取样收集。然后在指示灯被切换时关闭 DH 灯。取样过程是重复的荧光条件, 然后两个灯被关闭。
蛞蝓检测:在多相流系统中, 有效的样本采集需要组合采样技术, 这取决于运动蛞蝓的速度。在大约11毫米/秒的情况下, 检测算法变得比简单平均值更有效的阈值塞速度。在低速系统的情况下, 单光谱取样以均匀的间隔进行, 长度估计为2个流体蛞蝓 (约1厘米)。在通过这个取样过程获得的光谱中, 10 最佳光谱在蛞蝓的散装流体中心被隔绝使用一个五点局部方差的一个给定的波长在时间-400 毫微米为荧光和380毫微米为吸收-如所示在图 8。然而, 在较高的流体速度系统中, 单个运动塞的可用取样窗口超过了光谱仪的有效采样率。在这些情况下, 平均在一起收集的10光谱在均匀间隔被发现是充足的。
系统规格:通过应用多个 87 cm 扩展单元, 取样端口可以定位在反应堆油管长度变化 3-196 厘米。变化的流速和流动细胞运动的结合使原位光谱特征在居住时间范围为100毫秒-17 分钟, 采样率高达3万光谱每天。此外, 每种吸收或荧光光谱都具有显著的低化学消耗, 在取样时只需要2µL, 每光谱20µL (从启动到关闭)。这种高采样率和效率可归因于在单个平衡系统中通过平移流单元收集多达40种独特的光谱。在应用了反应堆稳定化、端口对齐和光谱分析校正过程之后, 该平台被证明对流单元30以上的完整传递 (图 9) 是准确的。在对甲苯参考的各自光源信号强度的描述中, 发现每个端口的给定波长计数误差在荧光和吸收信号中的所有30个刀路中保持在1% 以内。反应堆测量系统的这种稳定性使大量的材料发现、筛选和优化研究能够以最少的人工干扰进行, 从而使得从同一批前体收集的数据更加一致。
扩展采样空间:在现有的综合筛选研究中, 流体流速与停留时间的关系常常被混淆。例如, 对于实现固定流单元的特征, 通过调整净流体速度得到可变停留时间。然而, 正如先前讨论的对纳米晶生长动力学调谐的评价, 这种反应表征方法可能不足以研究广泛的胶体半导体合成快速成核和生长动力学。应用便携式取样系统将停留时间与流体速度脱钩, 以以前未探讨过的方式扩展取样空间。因此, 开发的模块化技术能够对下一代胶体纳米材料进行发现和探索性研究, 大大提高了合成条件的精度和控制。

半导体纳米晶, 特别是量子点的出现, 推动了电子材料研究和制造领域的重大进步。例如, 量子点指示灯1已经在商用的 "QLED" 显示中实现。最近, 在这类半导体中, perovskites 已经引起了对高效率和低成本光伏技术的大量兴趣和研究。自从2009年第一次以钙钛矿为基础的光伏演示以来,2在历史上的任何光伏技术中, 以钙钛矿为基础的太阳能电池的实验室规模功率转换效率都以无与伦比的速度增长。3,4除了以钙钛矿为基础的 PVs 的驱动兴趣外, 最近的各种方法描述了钙钛矿纳米晶的简便胶体合成, 为钙钛矿 QDs 的低成本、溶液相处理创造了机会。商用电子产品。5,6,7,8,9,10,11,12,13,14
在对胶体钙钛矿 QDs 进行大规模纳米制造的努力中, 首先必须对纳米晶生长通路和有效控制反应条件有更好的基本认识。然而, 对这些过程的现有研究传统上依赖于基于烧瓶的方法。批综合策略在材料表征和生产方面呈现出各种固有的局限性, 但最显著的是, 基于烧瓶的技术在筛选时间和前体消耗方面效率极低, 并表明烧瓶尺寸依赖性传质性质, 抑制合成一致性。15为了有效地研究胶体半导体纳米晶的生长途径, 通过大量的报告合成程序, 并在广泛的相关样品空间内, 需要更有效的筛选技术。在过去的两年中, 开发了一系列微流控技术, 用于研究胶体纳米晶, 利用化学消耗大大降低, 高通量筛选方法的可获得性, 以及可能的连续合成系统中的过程控制实现。12,16,17,18,19,20
在这项工作中, 我们报告的设计和开发的自动化微流控平台的高通量原位研究胶体半导体纳米晶。一种新颖的平移流单元、高度模块化的设计, 以及现成的管式电抗器和射流连接的集成, 形成了一个独特且适应性强的可重构平台, 直接应用于发现、筛选和优化胶体纳米晶。利用我们的检测技术 (即三端口流单元) 的平移能力, 首次证明了混合和反应时间刻度的系统解耦, 同时改进了取样效率和收集率超过传统的固定流动细胞方法。利用该平台, 使胶体纳米晶合成的高通量和精密带隙工程朝着连续的纳米制造策略发展。

<table><tbody><tr><td>Toluene</td><td>Fisher Scientific</td><td>AC364410010</td><td>99.85% extra over molecular sieves</td></tr><tr><td>Oleic acid</td><td>Sigma Aldrich</td><td>364525&amp;nbsp;ALDRICH</td><td>technical grade 90%</td></tr><tr><td>Cesium hydroxide (50 wt% in water)</td><td>Sigma Aldrich</td><td>232041 ALDRICH</td><td>50 wt% in water &gt; 99.9% trace metals</td></tr><tr><td>Lead(II) oxide</td><td>Sigma Aldrich</td><td>211907 SIGMA-ALDRICH</td><td>&gt; 99.9% trace metals basis</td></tr><tr><td>Tetraoctylammonium bromide</td><td>Sigma Aldrich</td><td>294136 ALDRICH</td><td>98%</td></tr><tr><td>1/16&quot; OD, 0.04&quot; ID FEP tubing</td><td>MicroSolv</td><td>48410-40</td><td></td></tr><tr><td>1/16&quot; OD, 0.02&quot; ID ETFE tubing</td><td>MicroSolv</td><td>48510-20</td><td></td></tr><tr><td>0.02&quot; thru hole PEEK Tee</td><td>IDEX Health &amp;amp; Science</td><td>P-712</td><td></td></tr><tr><td>1/4-28 ETFE flangeless ferrule for 1/16&quot;</td><td>IDEX Health &amp;amp; Science</td><td>P-200N</td><td></td></tr><tr><td>1/4-28 PEEK flangeless nut for 1/16&quot;</td><td>IDEX Health &amp;amp; Science</td><td>P-230</td><td></td></tr><tr><td>4-way PEEK L-valve</td><td>IDEX Health &amp;amp; Science</td><td>V-100L</td><td></td></tr><tr><td>Syringe pump</td><td>Harvard Apparatus</td><td>70-3007</td><td></td></tr><tr><td>8 mL stainless steel syringe</td><td>Harvard Apparatus</td><td>70-2267</td><td></td></tr><tr><td>25 mL glass syringe</td><td>Scientific Glass Engineering</td><td>25MDF-LL-GT</td><td></td></tr><tr><td>Optical breadboard</td><td>ThorLabs</td><td>MB1224</td><td></td></tr><tr><td>300 mm translation stage</td><td>ThorLabs</td><td>LTS300</td><td></td></tr><tr><td>Optical post</td><td>ThorLabs</td><td>TR2-4</td><td>TR2, TR3, or TR4</td></tr><tr><td>Optical post holder</td><td>ThorLabs</td><td>PH4-6</td><td>PH4 or PH6</td></tr><tr><td>365 nm LED</td><td>ThorLabs</td><td>M365LP1</td><td></td></tr><tr><td>LED driver</td><td>ThorLabs</td><td>LEDD1B</td><td></td></tr><tr><td>600 micron patch cord</td><td>Ocean Optics</td><td>QP600-1-SR</td><td></td></tr><tr><td>Deuterium-halogen light source</td><td>Ocean Optics</td><td>DH-2000-BAL</td><td></td></tr><tr><td>Miniature spectrometer</td><td>Ocean Optics</td><td>FLAME-S-XR1-ES</td><td></td></tr><tr><td>Multifuction I/O device (DAQ)</td><td>National Instruments</td><td>USB-6001</td><td></td></tr><tr><td>Virtual Instrument Software</td><td>National Instruments</td><td>LabVIEW 2015 SP1</td><td></td></tr></tbody></table>

a modular microfluidic technology for systematic studies of colloidal semiconductor nanocrystals

胶体半导体纳米晶, 称为量子点 (QDs), 是一个快速增长的类材料在商业电子, 如发光二极管 (led) 和光伏 (PVs)。在这一物质群中, 无机/有机 perovskites 在高电荷载流子导纳和寿命的情况下, 对高效、低成本的光伏制造具有显著的改善和潜力。尽管钙钛矿 QDs 在大型光伏发电和 LED 应用方面有机会, 但缺乏对其生长途径的基本和全面的了解, 阻碍了它们在连续纳米制造战略中的适应能力。传统的烧瓶筛选方法一般是昂贵的, 劳动密集型的, 不精确的, 以有效地表征广泛的参数空间和合成品种有关的胶体的反应。在这项工作中, 开发了一个全自主的微流控平台, 系统地研究了在连续流格式中与纳米晶胶体合成相关的大参数空间。该系统通过应用一种新的三端口流单元和模块化反应器扩展单元, 可快速采集 3-196 厘米范围内的荧光光谱和吸收光谱。可调整的反应器长度不仅分离的停留时间从速度依赖的传质, 它也极大地提高采样率和化学消耗量由于40唯一光谱的描述在一个单一平衡系统。采样率每天可达3万种独特的光谱, 条件涵盖 100 ms-17 分钟不等的居住时间4级。该系统的进一步应用将大大提高今后研究中材料发现和筛选的速度和精确度。本报告中详细介绍了系统材料和组装协议, 其中概述了自动取样软件和离线数据处理。

示例频谱:利用所讨论的微流控平台, 通过监测其吸收和荧光光谱的时间演化, 可以直接研究胶体半导体纳米晶在合成温度下的成核和生长阶段。在均匀混合条件下形成的纳米晶。图 5A显示一组在三端口流单元格的单个传递中获得的光谱示例。虽然单独的发射波长分布为高品质 LED 制造的应用提供了宝贵的洞察力, 但在实验验证的有效质量逼近模型中, 拟合吸收和发射带隙能量能够在整个合成过程中连续监测纳米粒的分布。14在不同流速和反应器长度的情况下获得了等效的谱集, 允许在100毫秒-17 分钟的居住时间内进行数据收集。
动力学可调谐纳米晶: 在多相流的液段内形成的轴对称回流模式, 实现了速度依赖性的传质控制。21关于速度依赖性的混合时间刻度的研究表明了钙钛矿 QDs 纳米晶生长通路的动力学调谐 (参见图 5B)。我们开发的模块化平台首次允许系统地研究早期混合时间对形成的纳米晶最终光学性能的影响。通过反应塞速度的变化, 同时保持所有其他参数常数, 观测到在等效停留时间的峰值发射波长与 25 nm 的差异。对胶体系统的进一步评价表明, 观测到的发射波长的差异保持在较长的停留时间, 从而产生稳定的动力学可调谐纳米晶。15
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57666/57666fig2.jpg"> 图 2.全自动反应筛分平台。此图显示了一个在14和15取样端口之间使用单个反应器扩展单元的完全组装的自动反应屏蔽平台. <a href="/files/ftp_upload/57666/57666fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57666/57666fig3.jpg"> 图 3.用于自动化平台操作的用户界面。此面板显示用户界面, 它允许控制和调整参数 (如注射器流速、光谱仪测量条件和取样位置), 以便在各种胶体半导体上进行特性分析。纳米晶合成。<a href="/files/ftp_upload/57666/57666fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57666/57666fig4.jpg"> 图 4.光谱分析更正的过程.此面板显示使用a通过端口进行光谱分析更正的过程。吸收谱通过B收集了超过20个取样端口。光谱对 455 nm 上的吸光度进行正常化, 该溶液中的胶体 CsPbBr3 perovskites 分散在甲苯和C中。各自的光致发光 (PL) 光谱D。正常化为 485 nm 信号强度。适应于无害的et 。15在皇家化学学会的允许下。<a href="/files/ftp_upload/57666/57666fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57666/57666fig5.jpg"> 图 5。动力学调谐的样本谱和演示。这些面板显示A。在一个多相、反应 CsPbBr3钙钛矿系统中, 在流动单元的单个通量内收集的吸收 (A) 和荧光 (I) 光谱, 以大约0.2 厘米/秒的平均蛞蝓速度移动, 以及B。峰值荧光波长 (λP) 作为停留时间的函数, 绘制了11个不同的平均塞速度, 范围从0.6 到130毫米/秒, 样本荧光光谱显示在停留时间和200s 和1.0 毫米/秒的蛞蝓速度 (顶部), 0.9 s 和75毫米/秒 (中间), 0.9 s 和130毫米/秒 (底部)。适应于无害的et 。15在皇家化学学会的允许下。<a href="/files/ftp_upload/57666/57666fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/57666/57666fig6.jpg"> 图 6.整个软件控制数据收集过程的流程流程图.这包括进程硬件的初始化、递归采样进度和平台的最终关闭。适应于无害的et 。15在皇家化学学会的允许下。<a href="/files/ftp_upload/57666/57666fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/57666/57666fig7.jpg"> 图 7.端口位置分配方法的自动化软件流程流程图.该算法首先运行指定数量的流单元的稳定传递, 然后通过光谱仪读取 LED 信号强度来进行最佳端口检测。<a href="/files/ftp_upload/57666/57666fig7large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/57666/57666fig8.jpg"> 图 8.采样多相光谱隔离.这些面板显示了A的多相谱隔离示例。荧光在500毫微米和B。随着时间的推移, 吸光度在 380 nm 的溶液中 perovskites 分散在甲苯。绿色区域表示理想采样时间的范围。面板C。显示了吸收光谱 (荧光素溶液) 比较多相取样方法, 因为它涉及到的塞速度。"方法" 表明, 采用了插拔检测算法, "Avg" 表示采样时间间隔均匀, 平均在一起。请注意, 应用于慢速移动蛞蝓的插拔检测方法产生的等效谱是较高速度系统的简单平均值。适应于无害的et 。15在皇家化学学会的允许下。<a href="/files/ftp_upload/57666/57666fig8large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/57666/57666fig9.jpg"> 图 9.跨阶段传递的测量稳定性演示.这是使用a跨阶段传递的测量稳定性的演示。吸收信号强度在500毫微米和B。在甲苯参考上的荧光强度为 380 nm, 由端口位置正常化, 平均超过30个流单元的全通。误差线表示95% 置信区间, 没有任何值偏离平均读数的1%。适应于无害的et 。15在皇家化学学会的允许下。<a href="/files/ftp_upload/57666/57666fig9large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about A Modular Microfluidic Technology for Systematic Studies of Colloidal Semiconductor Nanocrystals at JoVE.com

A Modular Microfluidic Technology for Systematic Studies of Colloidal Semiconductor Nanocrystals

本文详细介绍了一种用于胶体半导体纳米晶合成系统表征的模块化微流控屏蔽平台的操作和组装协议。通过完全可调的系统安排, 高效率的光谱收集可以在一个质量转移控制取样空间内跨4级的反应时间尺度进行。

胶体半导体纳米晶系统研究的模块化微流控技术

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are a rapidly growing class of materials in commercial electronics, such as light ...

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Nanyang Technological University

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JoVE Journal

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9.5K 次观看.  North Carolina State University. 本文详细介绍了一种用于胶体半导体纳米晶合成系统表征的模块化微流控屏蔽平台的操作和组装协议。通过完全可调的系统安排, 高效率的光谱收集可以在一个质量转移控制取样空间内跨4级的反应时间尺度进行。

视频: A Modular Microfluidic Technology for Systematic Studies of Colloidal Semiconductor Nanocrystals

Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures

The behavior of confined colloidal suspensions with attractive interparticle interactions is critical to the rational design of materials for directed assembly1-3, drug delivery4, improved hydrocarbon recovery5-7, and flowable electrodes for energy storage8. Suspensions containing fluorescent colloids and non-adsorbing polymers are appealing model systems, as the ratio of the polymer radius of gyration to the particle radius&#160;and concentration of polymer control the range and strength of the interparticle attraction, respectively. By tuning the polymer properties and the volume fraction of the colloids, colloid fluids, fluids of clusters, gels, crystals, and glasses can be obtained9.&#160;Confocal microscopy, a variant of fluorescence microscopy, allows an optically transparent and fluorescent sample to be imaged with high spatial and temporal resolution in three dimensions. In this technique, a small pinhole or slit blocks the emitted fluorescent light from regions of the sample that are outside the focal volume of the microscope optical system. As a result, only a thin section of the sample in the focal plane is imaged. This technique is particularly well suited to probe the structure and dynamics in dense colloidal suspensions at the single-particle scale: the particles are large enough to be resolved using visible light and diffuse slowly enough to be captured at typical scan speeds of commercial confocal systems10. Improvements in scan speeds and analysis algorithms have also enabled quantitative confocal imaging of flowing suspensions11-16,37.&#160;In this paper, we demonstrate confocal microscopy experiments to probe the confined phase behavior and flow properties of colloid-polymer mixtures. We first prepare colloid-polymer mixtures that are density- and refractive-index matched. Next, we report a standard protocol for imaging quiescent dense colloid-polymer mixtures under varying confinement in thin wedge-shaped cells. Finally, we demonstrate a protocol for imaging colloid-polymer mixtures during microchannel flow.

Confocal microscopy is used to image quiescent and flowing colloid-polymer mixtures, which are studied as model systems for attractive suspensions. Image analysis algorithms are used to calculate structural and dynamic metrics for the colloidal particles that measure changes due to geometric confinement.

密闭静态和流动胶体聚合物混合物的共聚焦成像

The behavior of confined colloidal suspensions with attractive interparticle interactions is critical to the rational design of materials for directed ...

科研

化学

Fluorescence detection methods for microfluidic droplet platforms

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that accompany system miniaturisation. Advantages include the ability to efficiently process nano- to femoto- liter volumes of sample, facile integration of functional components, an intrinsic predisposition towards large-scale multiplexing, enhanced analytical throughput, improved control and reduced instrumental footprints.1
In recent years much interest has focussed on the development of droplet-based (or segmented flow) microfluidic systems and their potential as platforms in high-throughput experimentation.2-4 Here water-in-oil emulsions are made to spontaneously form in microfluidic channels as a result of capillary instabilities between the two immiscible phases. Importantly, microdroplets of precisely defined volumes and compositions can be generated at frequencies of several kHz. Furthermore, by encapsulating reagents of interest within isolated compartments separated by a continuous immiscible phase, both sample cross-talk and dispersion (diffusion- and Taylor-based) can be eliminated, which leads to minimal cross-contamination and the ability to time analytical processes with great accuracy. Additionally, since there is no contact between the contents of the droplets and the channel walls (which are wetted by the continuous phase) absorption and loss of reagents on the channel walls is prevented.
Once droplets of this kind have been generated and processed, it is necessary to extract the required analytical information. In this respect the detection method of choice should be rapid, provide high-sensitivity and low limits of detection, be applicable to a range of molecular species, be non-destructive and be able to be integrated with microfluidic devices in a facile manner. To address this need we have developed a suite of experimental tools and protocols that enable the extraction of large amounts of photophysical information from small-volume environments, and are applicable to the analysis of a wide range of physical, chemical and biological parameters. Herein two examples of these methods are presented and applied to the detection of single cells and the mapping of mixing processes inside picoliter-volume droplets. We report the entire experimental process including microfluidic chip fabrication, the optical setup and the process of droplet generation and detection.

Droplet-based microfluidic platforms are promising candidates for high throughput experimentation since they are able to generate picoliter, self-compartmentalized vessels inexpensively at kHz rates. Through integration with fast, sensitive and high resolution fluorescence spectroscopic methods, the large amounts of information generated within these systems can be efficiently extracted, harnessed and utilized.

荧光检测方法，为微流体液滴平台

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that ...

生物工程

Microfluidic Chips Controlled with Elastomeric Microvalve Arrays

Miniaturized microfluidic systems provide simple and effective solutions for low-cost point-of-care diagnostics and high-throughput biomedical assays. Robust flow control and precise fluidic volumes are two critical requirements for these applications. We have developed microfluidic chips featuring elastomeric polydimethylsiloxane (PDMS) microvalve arrays that: 1) need no extra energy source to close the fluidic path, hence the loaded device is highly portable; and 2) allow for microfabricating deep (up to 1 mm) channels with vertical sidewalls and resulting in very precise features.

The PDMS microvalves-based devices consist of three layers: a fluidic layer containing fluidic paths and microchambers of various sizes, a control layer containing the microchannels necessary to actuate the fluidic path with microvalves, and a middle thin PDMS membrane that is bound to the control layer. Fluidic layer and control layers are made by replica molding of PDMS from SU-8 photoresist masters, and the thin PDMS membrane is made by spinning PDMS at specified heights. The control layer is bonded to the thin PDMS membrane after oxygen activation of both, and then assembled with the fluidic layer. The microvalves are closed at rest and can be opened by applying negative pressure (e.g., house vacuum). Microvalve closure and opening are automated via solenoid valves controlled by computer software.

Here, we demonstrate two microvalve-based microfluidic chips for two different applications. The first chip allows for storing and mixing precise sub-nanoliter volumes of aqueous solutions at various mixing ratios. The second chip allows for computer-controlled perfusion of microfluidic cell cultures.

The devices are easy to fabricate and simple to control. Due to the biocompatibility of PDMS, these microchips could have broad applications in miniaturized diagnostic assays as well as basic cell biology studies.

We demonstrate protocols for manufacturing and automating elastomeric polydimethylsiloxane (PDMS)-based microvalve arrays that need no extra energy to close and feature photolithographically defined precise volumes. A parallel subnanoliter-volume mixer and an integrated microfluidic perfusion system are presented.

微流控芯片控制，弹性微阀阵列

Miniaturized microfluidic systems provide simple and effective solutions for low-cost point-of-care diagnostics and high-throughput biomedical assays.  ...

生物学

Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles

Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its transparency. Due to the softness of the PDMS material, however, it is challenging to use PDMS for building nanochannels. The channels tend to collapse easily during plasma bonding. In this paper, we present an evaporation-driven self-assembly method of silica colloidal nanoparticles to create nanofluidic junctions with sub-50 nm pores between two microchannels. The pore size as well as the surface charge of the nanofluidic junction is tunable simply by changing the colloidal silica bead size and surface functionalization outside of the assembled microfluidic device in a vial before the self-assembly process. Using the self-assembly of nanoparticles with a bead size of 300 nm, 500 nm, and 900 nm, it was possible to fabricate a porous membrane with a pore size of ~45 nm, ~75 nm and ~135 nm, respectively. Under electrical potential, this nanoporous membrane initiated ion concentration polarization (ICP) acting as a cation-selective membrane to concentrate DNA by ~1,700 times within 15 min. This non-lithographic nanofabrication process opens up a new opportunity to build a tunable nanofluidic junction for the study of nanoscale transport processes of ions and molecules inside a PDMS microfluidic chip.

We propose a simple self-assembly technique of silica colloidal nanoparticles to create a nanofluidic junction between two microchannels in polydimethylsiloxane (PDMS). Using this technique, a nanoporous bead membrane with a pore size down to ~45 nm was built inside a microchannel and applied to electrokinetic preconcentration of DNA samples.

通过胶体粒子自组装过程创建在PDMS微流控芯片分50纳米的纳米流体结

Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its ...

工程学

Millifluidics for Chemical Synthesis and Time-resolved Mechanistic Studies

Procedures utilizing millifluidic devices for chemical synthesis and time-resolved mechanistic studies are described by taking three examples. In the first, synthesis of ultra-small copper nanoclusters is described. The second example provides their utility for investigating time resolved kinetics of chemical reactions by analyzing gold nanoparticle formation using in situ X-ray absorption spectroscopy. The final example demonstrates continuous flow catalysis of reactions inside millifluidic channel coated with nanostructured catalyst.

Millifluidic devices are utilized for controlled synthesis of nanomaterials, time-resolved analysis of reaction mechanisms and continuous flow catalysis.

Millifluidics的化学合成和时间分辨机理研究

Procedures utilizing millifluidic devices for chemical synthesis and time-resolved mechanistic studies are described by taking three examples. In the ...

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 &#181;m grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography. As almost every crystal can be used for diffraction data collection, these microfluidic chips are a very efficient crystal delivery method.

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes in detail how to fabricate and operate microfluidic devices for X-ray diffraction data collection at room temperature. Additionally, it describes how to monitor protein crystallization by dynamic light scattering and how to process and analyze obtained diffraction data.

用于原位晶体 x 射线衍射和原位的微流控芯片系列晶体学的动态光散射

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The ...

Window on a Microworld: Simple Microfluidic Systems for Studying Microbial Transport in Porous Media

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in the environment, as well as directly for the transmission of pathogens to drinking water supplies. Natural porous media is composed of an intricate physical topology, varied surface chemistries, dynamic gradients of nutrients and electron acceptors, and a patchy distribution of microbes. These features vary substantially over a length scale of microns, making the results of macro-scale investigations of microbial transport difficult to interpret, and the validation of mechanistic models challenging. Here we demonstrate how simple microfluidic devices can be used to visualize microbial interactions with micro-structured habitats, to identify key processes influencing the observed phenomena, and to systematically validate predictive models. Simple, easy-to-use flow cells were constructed out of the transparent, biocompatible and oxygen-permeable material poly(dimethyl siloxane). Standard methods of photolithography were used to make micro-structured masters, and replica molding was used to cast micro-structured flow cells from the masters. The physical design of the flow cell chamber is adaptable to the experimental requirements: microchannels can vary from simple linear connections to complex topologies with feature sizes as small as 2 &mu;m. Our modular EcoChip flow cell array features dozens of identical chambers and flow control by a gravity-driven flow module. We demonstrate that through use of EcoChip devices, physical structures and pressure heads can be held constant or varied systematically while the influence of surface chemistry, fluid properties, or the characteristics of the microbial population is investigated. Through transport experiments using a non-pathogenic, green fluorescent protein-expressing Vibrio bacterial strain, we illustrate the importance of habitat structure, flow conditions, and inoculums size on fundamental transport phenomena, and with real-time particle-scale observations, demonstrate that microfluidics offer a compelling view of a hidden world.

Microfluidic devices can be used to visualize complex natural processes in real time and at the appropriate physical scales. We have developed a simple microfluidic device that mimics key features of natural porous media for studying growth and transport of bacteria in the subsurface.

窗口上的一个微观世界：简单的微流体系统为研究多孔介质中的微生物运输

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in ...

Microfluidic Platform with Multiplexed Electronic Detection for Spatial Tracking of Particles

Microfluidic processing of biological samples typically involves differential manipulations of suspended particles under various force fields in order to spatially fractionate the sample based on a biological property of interest. For the resultant spatial distribution to be used as the assay readout, microfluidic devices are often subjected to microscopic analysis requiring complex instrumentation with higher cost and reduced portability. To address this limitation, we have developed an integrated electronic sensing technology for multiplexed detection of particles at different locations on a microfluidic chip. Our technology, called Microfluidic CODES, combines Resistive Pulse Sensing with Code Division Multiple Access to compress 2D spatial information into a 1D electrical signal. In this paper, we present a practical demonstration of the Microfluidic CODES technology to detect and size cultured cancer cells distributed over multiple microfluidic channels. As validated by the high-speed microscopy, our technology can accurately analyze dense cell populations all electronically without the need for an external instrument. As such, the Microfluidic CODES can potentially enable low-cost integrated lab-on-a-chip devices that are well suited for the point-of-care testing of biological samples.

We demonstrate a microfluidic platform with an integrated surface electrode network that combines resistive pulse sensing (RPS) with code division multiple access (CDMA), to multiplex detection and sizing of particles in multiple microfluidic channels.

与复用电子检测的粒子的空间跟踪微流体平台

Microfluidic processing of biological samples typically involves differential manipulations of suspended particles under various force fields in order to ...

Generation of Dynamical Environmental Conditions using a High-Throughput Microfluidic Device

Mimicking in vivo environmental conditions is crucial for in vitro studies on complex life machinery. However, current techniques targeting live cells and organs are either highly expensive, like robotics, or lack nanoliter volume and millisecond time accuracy in liquid manipulation. We herein present the design and fabrication of a microfluidic system, which consists of 1,500 culture units, an array of enhanced peristaltic pumps and an on-site mixing modulus. To demonstrate the capacities of the microfluidic device, neural stem cell (NSC) spheres are maintained in the proposed system. We observed that when the NSC sphere is exposed to CXCL in day 1 and EGF in day 2, the round-shaped conformation is well maintained. Variation in the input order of 6 drugs causes morphological changes to the NSC sphere and the expression level representative marker for NSC stemness (i.e., Hes5 and Dcx). These results indicate that dynamic and complex environmental conditions have great effects on NSC differentiation and self-renewal, and the proposed microfluidic device is a suitable platform for high throughput studies on the complex life machinery.

We present a microfluidic system for high throughput studies on complex life machinery, which consists of 1500 culture units, an array of enhanced peristaltic pumps and an on-site mixing modulus. The microfluidic chip allows for the analysis of the highly complex and dynamic micro-environmental conditions in vivo.

使用高通量微流体设备生成动态环境条件

Mimicking in vivo environmental conditions is crucial for in vitro studies on complex life machinery. However, current techniques targeting live cells and ...

用于组合插头生产的微流体装置的设置

Bilayer Microfluidic Device for Combinatorial Plug Production

Droplet microfluidics is a versatile tool that allows the execution of a large number of reactions in chemically distinct nanoliter compartments. Such systems have been used to encapsulate a variety of biochemical reactions - from incubation of single cells to implementation of PCR reactions, from genomics to chemical synthesis. Coupling the microfluidic channels with regulatory valves allows control over their opening and closing, thereby enabling the rapid production of large-scale combinatorial libraries consisting of a population of droplets with unique compositions. In this paper, protocols for the fabrication and operation of a pressure-driven, PDMS-based bilayer microfluidic device that can be utilized to generate combinatorial libraries of water-in-oil emulsions called plugs are presented. By incorporating software programs and microfluidic hardware, the flow of desired fluids in the device can be controlled and manipulated to generate combinatorial plug libraries and to control the composition and quantity of constituent plug populations. These protocols will expedite the process of generating combinatorial screens, particularly to study drug response in cells from cancer patient biopsies.

作者聚焦：在精准肿瘤学中整合计算和实验方法

The fabrication of a polydimethylsiloxane (PDMS)-based bilayer device for the production of combinatorial libraries in water-in-oil emulsions (plugs) is presented here. The necessary hardware and software required to automate plug production are detailed in the protocol, and the production of a quantitative library of fluorescent plugs is also demonstrated.

用于组合塞生产的双层微流控装置

Droplet microfluidics is a versatile tool that allows the execution of a large number of reactions in chemically distinct nanoliter compartments. Such ...