CAREER: Thermal Gradient Microflow Calorimetry using Anisotropic Temperature Sensors

Louisiana Tech University, Ruston LA

Investigators

Abstract

PI: Crews CBET-1151148 The 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.