Experimental validation of computational models for mass transport through micro heterogeneous membranes

This work describes a setup for the experimental and theoretical study of the mass transport of a penetrant through a two-dimensional model-material microstructure consisting in a homogeneous matrix with slender obstacles. Experiments were performed using polydimethylsiloxane (PDMS) specimens with a controlled pattern of randomly distributed laser-ablated microscopic slender holes that mimic the obstacles to the diffusion of the penetrant, 1-octadecanol (ODOL). Mass transport of ODOL throughout the patterned PDMS matrix was monitored by means of Confocal Raman microscopy. Rigorous numerical simulations of ODOL transport in transient regime were performed using the Boundary Element Method for exactly the same model-material microstructure topology used in the experimental tests. It was found that both, experiments and BEM simulations very well capture local barrier effects of the obstacles to the ODOL transport. The whole strategy provides a valuable base for validation and experimental verification of theoretical models of mass transport through heterogeneous membranes with complex barrier structure.