In this work, fluid–structure interaction (FSI) simulations, as well as non-FSI ones, are conducted to study the behavior of a functionally graded (FG) pH-sensitive micro-valve. The FEM analysis of the hydrogel is performed in ABAQUS while the fluid domain is analyzed in ANSYS fluent. To investigate the FSI and FG effects, both FSI and non-FSI simulations are performed for pH-sensitive micro-valve with homogeneous cross-linking distribution beside the FG cases. Two simulation domains are coupled by using a third-party software named MpCCI for both FSI and non-FSI simulations. For the FG hydrogel, linear and exponential property distributions are considered. The obtained results show a significant difference between the FG and homogeneous hydrogel behavior for both simulation methods. Additionally, the results emphasize that FSI consideration has a crucial role in the design of these smart devices. Especially, remarkable difference is observed for the closing pH of the micro-valve as well as the flow-rate diagrams. For example, a leakage is observed in FSI simulations for the closing pH of the non-FSI simulations that indicates the importance of the FSI effect. Finally, the effect of the cross-linking density distribution and the inlet pressure of micro-valve are studied and the results are analyzed.
