Microreaction technologies are employed in various applications like space propulsion, atomization, drug delivery and in lab-on-chip applications. Mixing index measurement in micro reactors is essential to assess the performance of the proposed micro mixer. A major roadblock in the design of a micromixer is its assessment and determination of mixing index during the operation due to the complex flow characteristics and mass transfer that occur during the mixing of fluids or reactants. Sensor design is thus vital in analyzing the performance of micro mixers during operation. Infrared sensing is a versatile flow visualization technique which has been effectively used previously to characterize two phase flows in conventional macro channels. The present work develops a robust multiphysics simulation framework and provides a comprehensive characterization of an infrared sensor to perform online assessment of micromixers during their operation. This study considers the case of an optimized passive micromixer described in several literatures and models the microfluidic mixing between silica nanoparticles and distilled water at various concentrations. Further coupling was done by applying the physics of ray optics to understand the performance of an infrared sensor. The variation in infrared sensor output with the mixing index is presented based on the multiphysics coupling. With this analysis, the characteristic output of an infrared sensor can be inferred for any practical microfluidic mixing and microreactor application, thus helping the instrumentation design for online performance assessment of micromixers.

微反应技术用于各种应用，如空间推进、雾化、药物输送和芯片实验室应用。微型反应器中的混合指数测量对于评估所提出的微型混合器的性能至关重要。由于流体或反应物混合过程中发生的复杂流动特性和传质，微混合器设计的一个主要障碍是其在操作过程中对混合指数的评估和确定。因此，传感器设计对于分析微型混合器在运行期间的性能至关重要。红外传感是一种通用的流动可视化技术，以前已有效地用于表征传统宏通道中的两相流。目前的工作开发了一个强大的多物理场仿真框架，并提供了红外传感器的综合表征，以在微混合器的运行过程中对其进行在线评估。本研究考虑了多篇文献中描述的优化被动微混合器的情况，并对不同浓度的二氧化硅纳米粒子和蒸馏水之间的微流体混合进行建模。通过应用射线光学物理学来了解红外传感器的性能，完成了进一步的耦合。基于多物理场耦合呈现了红外传感器输出随混合指数的变化。通过这种分析，可以为任何实际的微流体混合和微反应器应用推断红外传感器的特征输出，