Concentration measurement of a mixture using an infrared transceiver

Abstract

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.