CAREER: Thermal Gradient Microflow Calorimetry using Anisotropic Temperature Sensors

PI：CrewsCBET-1151148拟议的工作将寻求表征和应用一种独特类型的单向温度传感器。这种传感器的实用性将在差示扫描量热法（DSC）领域内最能感受到。DSC是一门广泛的科学，它检查给定物质在由温度变化引发的分子间反应期间释放或吸收的能量。这些能量变化通常在样品随时间稳定加热或冷却时测量。这种方法本质上是一种缓慢的方法，因为在任何时刻物质内温度变化的存在都会给系统带来误差。本项目将寻求改变这种模式。温度梯度本身可以用作分析的中心驱动机制，而不是使加热减速以使温度梯度无关紧要。这可以在没有信号失真的情况下通过采用单向温度传感器来实现，使得由快速加热引起的温度变化对于能量测量基本上是不可见的。这将允许以更快的速率进行高精度DSC，从而揭示分子间反应的最难以捉摸的动力学。此外，这种方法将允许DSC仪器被设计用于现场采样，因为驱动分析的温度梯度自然地由常见事件产生，例如：将探针插入烘箱或熔炉中，局部点火或燃烧过程，或者甚至简单地通过管呼气。正是这种独特的传感器使温度梯度能够发挥作用，而不是出现问题。虽然有很多潜在的有用性，这种拟议的分析技术，它代表了一个显着的偏离标准做法，有根本不同的热传输行为。因此，围绕其效用的基础科学目前还不完整。 该提案的智力价值与这种新DSC技术的性能表征有关。所提出的系统是独特的，因为它将检测反应热作为功率而不是能量。该项目将评估这将对热信号的产生、积累、检测和随后的消耗产生的影响。这种提出的DSC方法也被独特地表征为稳定的热传递（称为“等通量”），而不是可忽略的热传递（称为“准平衡”）环境。这项工作将评估两种情况下的相对测量灵敏度，以及每种类型的系统在分析之间返回其基线温度分布的速度。还将努力发现一种优化方案，通过该方案可以进一步提高等通量系统的性能。除了这项工作将对量热科学界产生直接影响外，这项工作还包含一个教育部分，将为多个团体服务。许多新的学习机会将通过新课程开发，高级设计团队赞助和学生研究机会的延续在大学内提供。这项工作的范围还包括扩大正在进行的努力，以扩大微流体研究技术的可及性。将开展更多的外联活动，影响任职人数不足的群体。一个非常成功的夏令营计划-部分通过NSF赞助开发-将被修改为便携式格式。然后，教育工作者将能够在整个地区建立这一计划。这将对经济紧张的地区产生特别影响，在这些地区，参加集中营方案一般不现实。

PI: CrewsCBET-1151148The proposed effort will seek to characterize and apply a unique type of one-directional temperature sensor. The utility of such a sensor will be most felt within the field of differential scanning calorimetry (DSC). DSC is a broad science that examines the energy given off or absorbed by a given substance during intermolecular reactions triggered by temperature change. These energy changes are typically measured while a sample is steadily heated or cooled over time. This approach is innately a slow one, since the presence of temperature variation within the substance at any moment introduces error into the system. This project will seek to change that paradigm. Rather than decelerate heating to make temperature gradients insignificant, temperature gradients themselves can be used as the central driving mechanism of the analysis. This can be achieved without signal distortion by employing a one-directional temperature sensor in a way that the temperature variation caused by rapid heating is essentially invisible to the energy measurement. This will allow for high-precision DSC at faster rates, thereby exposing the most elusive kinetics of the intermolecular reactions. Moreover, this approach will allow for DSC instrumentation to be designed for field sampling, since the temperature gradients driving the analysis naturally result from common events, such as: insertion of a probe into an oven or furnace, a localized ignition or combustion process, or even simply exhaling through a tube. It is the unique sensor that will enable temperature gradients to be functional rather than problematic. Although there is much potential usefulness for this proposed analytical technique, it represents a significant deviation from standard practice, having fundamentally different thermal transport behavior. Therefore, the basic science surrounding its utility is currently incomplete. The intellectual merit of the proposal relates to the performance characterization of this new DSC technique. The proposed system is unique in that it will detect the heat of reaction as power rather than as energy. This project will evaluate the impact this will have on the generation, buildup, detection, and subsequent depletion of heat signatures. This proposed DSC methodology is also uniquely characterized as a steady heat transfer (called "iso-flux") rather than a negligible heat transfer (called "quasi-equilibrium") environment. This work will evaluate the relative measurement sensitivities of both scenarios, as well as the speed with which each type of system will return to its baseline temperature distribution between analyses. Effort will also be made to discover an optimization scheme by which isoflux system performance can be further enhanced.In addition to the direct impact this effort will have on the calorimetric science community, this work contains an educational component that will serve multiple groups. Many new learning opportunities will be made available within the university through a continuation of new course development, senior design team sponsorship, and student research opportunities. The scope of this work also includes an expansion of ongoing efforts to expand the accessibility of microfluidic research technologies. Additional outreach activities will be performed which will impact under-represented populations. A highly successful summer camp program - developed in part through NSF-sponsorship - will be modified into a portable format. Educators will then be able to establish this program across the region. This will have particular impact on the economically-stressed areas, where participation in the centralized camp programs is not generally realistic.