Development and Study of Self-Assembled Microthermometers

CBET-0755704Sokolov远程微型温度计用于测量和研究各种热传输过程，包括生物技术、微反应器、微流体、环境研究等。目前，各种染料、颜料、微胶囊染料和液晶被用来绘制大体积流体中的温度。所有这些染料和微粒都有严重的局限性：要么温度敏感度太低，要么温度工作范围太窄，它们可能会污染所使用的介质，和/或温度信号可能与介质化学变化引起的信号混淆。在此，我们建议开发一种新型的胶体荧光二氧化硅颗粒，它将能够“测量”环境的温度，并且将不会出现上述问题。温度将作为粒子荧光的函数来获得。为了制造这样的颗粒，我们建议使用最近发现的自组装微米级纳米多孔二氧化硅胶体。荧光分子将被封装在这些粒子的圆柱形纳米通道中。这种粒子/探测器可用于研究液体和环境中的温度和传输现象。荧光染料在纳米通道的有效一维受限几何中的光学行为的研究也是基本感兴趣的。除了增强的温度敏感性，我们的初步研究表明，一些荧光染料的包裹导致了相当高的荧光，例如，比最近报道的嵌入量子点的类似尺寸的聚合物粒子的荧光高170-300倍。这使得这些颗粒成为有史以来合成的最亮的荧光珠。因此，建议的温度计将很容易被追踪。智能价值：这项研究的发现将导致开发和理解新型超亮荧光粒子，这些粒子将用作微米尺寸的温度计。每个这样的温度计都可以通过测量这些粒子辐射的荧光来远程访问。我们将研究荧光染料在限定的纳米通道中的光学行为。我们将研究包裹染料后温度敏感度增强的本质。这将允许开发针对灵敏度、重复性和稳定性进行优化的微型温度计。广泛的影响：微型温度计将用于研究和工业应用，这些应用需要研究大量透明介质中的温度分布和流动。这项拟议的研究预计将对社会产生很大影响。粒子的良好视觉外观和迷人的内部结构将有助于制作获胜的公开演示文稿和有吸引力的出版物。这项研究的结果将通过互联网、专业出版物、通俗文学传播，并将在包括学生会议在内的会议上公布。这将帮助更多的美国学生接触科学，向他们展示科学研究可以提供的真正兴趣和兴奋。变革性：拟议的微型温度计预计将在广泛的应用中使用：作为绘制温度场的“智能灰尘”，以优化建筑物、办公室、工厂中的热流，最大限度地减少建筑物、办公室、工厂中的能量损失；作为固体中的温度标签，使人们从根本上了解高能光束(如激光)与固体表面的相互作用。此外，这些颗粒表面是二氧化硅，在生物上是良性的，因此它们可以用于生物医学应用，需要可视化器官和材料中的温度分布。最后，微型温度计将被用来研究亚微米范围内的热传递，这对能量转换、生物技术、微电子学和生化检测仍然具有重要意义。

CBET-0755704SokolovRemotely accessed microthermometers are of great interest for measuring / studying various thermal transport processes, including biotechnology, microreactors, microfluidics, environmental study, etc. At the present time, various dyes, pigments, microencapsulated dyes, and liquid crystals are used to map the temperature in bulk fluid. All these dyes and particulates have serious limitations: either rather small temperature sensitivity or too narrow working range of temperatures, they can contaminate the medium in which they are being used, and/or the temperature signal can be confused with the signals from a possible change of the medium chemistry.Here we propose to develop a novel class of colloidal fluorescent silica particles which will be able to "measure" the temperature of the environment, and which will be free from the problems listed above. The temperature will be obtained as a function of the fluorescence of the particles. To make such particles, we propose to use recently discovered self-assembled micron-sized nanoporous silica colloids. Fluorescent molecules will be encapsulated inside the cylindrical nanochannels of those particles. Such particles/detectors can be used to study temperature and transport phenomena in both liquids and the ambient environment. The study of the optical behavior of fluorescent dyes in effectively one-dimensional confined geometries of nanochannels is also of fundamental interest. Apart from the enhanced temperature sensitivity, our preliminary study shows that encapsulation of some fluorescent dyes results in a rather high fluorescence, which is, for example, 170-300 times higher than fluorescence of similar-sized polymeric particles with embedded quantum dots reported recently. This makes these particles the brightest fluorescent beads ever synthesized. Thus, the proposed microthermometers will be easily traceable.Intellectual Merit: findings of this study will result in the development and understanding of novel ultra-bright fluorescent particles that will act as thermometers of micron size. Each such thermometer will be remotely accessible by measuring the fluorescent light radiated by these particles. Optical behavior of fluorescent dyes in a confined well-defined geometry of nanochannels will be studied. We will study the nature of the enhancement in temperature sensitivity after encapsulating the dyes. This will allow development of the micro-thermometers optimized for sensitivity, repeatability, and stability.Broader impact: Microthermometers will be used for both research and industrial applications which require studying temperature distributions and flows in a bulk of transparent media. The proposed research is expected to have a high impact on society. Great visual appearance of the particles and fascinating internal structure will help to make winning public presentations and attractive publications. The results of this research will be disseminated over the Internet, professional publications, popular literature, and will be presented at conferences, including student conferences. This will help to bring more American students to science by showing them the real interest and excitement that scientific research can provide.Transformative nature: The proposed microthermometers are expected to be used in a broad variety of applications: as "smart dust" for mapping temperature fields to optimize the heat flows to minimize energy losses in buildings, offices, factories, optimizing energy-consuming manufacturing processes, etc; as temperature tags in solids to bring fundamental understanding of the interaction of energetic beams, such as lasers, for the solid surfaces. Furthermore, being silica on the outside, these particles will be biologically benign, so they can be used in biomedical applications that require visualization of the temperature distributions in organs and materials. Finally, the microthermometers will be used to study heat transfer at the scales down to the submicron range, which is of continuing importance to energy conversion, biotechnology, microelectronics, and biochemical detection.