Microfluidic flow control strategies for organ-on-a-chip devices: a critical review

Abstract Organs-on-a-chip has become a powerful tool in the fields of molecular biology and biomedical engineering, allowing the simulation of organ conditions for toxicological and pharmacological tests. The platform allows for the variation of test parameters, enabling the evaluation of different and specific scenarios. The correct control of these parameters is crucial for determining the effectiveness of the test and must be considered in project planning. This review briefly presents the common types of flow in microchannels. Furthermore, three main forms of flow control in organs-on-a-chip will be discussed: (1) The use of micropumps (hydraulic, electric, and pneumatic); (2) Using hydrostatic pressure (gravity and pressure columns); and (3) Using pneumatic pressure. Along with the presentation of each method, an overview of the types of cell culture applied in each case, the simulation parameters, and the main benefits and challenges of using such approaches will also be discussed. This work aims to be a guide on different flow application methods, considering experimental goals, compatibility with the cell culture, and simulation conditions.