4D synchrotron microtomography and pore-network modelling for direct <i>in situ</i> capillary flow visualization in 3D printed microfluidic channels
Agnese Piovesan, Tim Van De Looverbosch, Pieter Verboven, Clement Achille, Cesar Parra‐Cabrera, Élodie Boller, Yin Cheng, Rob Ameloot, Bart Nicolaı̈
Abstract
Powder-based 3D printing was employed to produce porous, capillarity-based devices suitable for passive microfluidics. Capillary imbibition in such devices was visualized in situ through dynamic synchrotron X-ray microtomography performed at the European Synchrotron Radiation Facility (ESRF) with sub-second time resolution. The obtained reconstructed images were segmented to observe imbibition dynamics, as well as to compute the system effective contact angle and to generate a pore-network to model capillary imbibition. A contact angle gradient was observed resulting in a preferential wicking direction, with the central portion of the microfluidic channel filling faster than the edge areas. The contact angle analysis and the pore-network model results suggest that this is due to spatial variations in the material surface properties arising from both the 3D printing and the subsequent drying processes.