Numerical study on the fluid-structure interaction and species transport in a piezoresistive microcantilever-based biosensor

In this study, we present numerical simulations of the flow-induced deflection of a microcantilever beam and the distribution of a passive analyte inside a microfluidic cell for a piezoresistive biosensor. The numerical implementation was validated using semi-analytical models and previously reported experimental measurements. The primary objective of the study is to understand the impact of the flow on the cantilever's behavior and use this knowledge in the decision-making process for a microfluidic cell design for a piezoresistive biosensor. To accomplish this, the results for three different inlet/outlet configurations allow us to describe the dynamics of the fluid-structure interaction, finding that, for small times, the flow is symmetrical around the microcantilever. As time passes, two vortices surround the microcantilever, resulting in an asymmetric flow distribution. Throughout the entire range of analyzed inlet flow rates, it is evident that the inlet/outlet configuration significantly influences the deflection and stress sustained by the cantilever. Similarly, these configurations affect how the concentration of an analyte sample distributes on the detecting surface. The in-depth understanding of the flow dynamics within the microfluidic cell and its effect on the cantilever, as provided by the simulations, can be used to propose design recommendations aimed at reducing the noise due to the flow, ultimately achieving high sensitivity in these types of devices.