Surface bound adsorption in a microfluidic T-sensor: Numerical comparison and optimization of 2D and 3D models and of sensor designs

We compare models in two and three spatial dimensions for describing the interplay of convection, diffusion and adsorption in the main channel of a microfluidic T-sensor. A two dimensional model with additional parameters for quantifying film diffusion is shown to describe the sensor equally well but with significantly reduced computational effort as compared to the three dimensional model. Optimal values of the additional parameters are determined and discussed for varied diffusion coefficients and channel heights. The two dimensional model is then applied for studying the impact of varied geometries of a functionalized surface region on the obtained signals. Finally, a specific combination of geometries and measurement times is proposed and computationally verified for achieving almost linear sensor signals over wide concentration ranges.