Flow visualization in microbioreactors: Techniques, applications, and challenges in bioprocessing

Microbioreactors are crucial in both laboratory research and industrial applications across chemical engineering, biomedical diagnostics, and bioprocessing. Understanding fluid dynamics at the microscale has become increasingly important since there is a growing interest in improving microbioreactor performance through design modifications in shape, materials, and operational conditions. This paper provides an extensive review of flow visualization techniques used in microbioreactors, including both experimental and computational approaches. The article discusses how various flow visualization methods such as micro-Particle Image Velocimetry (µPIV), Laser-Induced Fluorescence (LIF), Computational Fluid Dynamics (CFD) etc. can be utilized for evaluating microscale flow and mixing efficiency. The impact of micromixing on microreactor performance, affected by parameters such as temperature, pH, pressure, and reactor geometry, is investigated using case studies and theoretical research. The analysis also highlights existing flow visualization problems, notably those related to scale-up and real-time monitoring. The future possibilities for improving microbioreactor design and operation include high-resolution 3D imaging techniques along with CFD simulations, which provide predictive insights into flow behaviors at different operating conditions and provide deeper insights into complex flow patterns. This study provides a roadmap for scientists and engineers looking to improve microbioreactor systems for high-performance bioprocessing applications.