Percolation in Isotropically Directed Lattices of Liquid Diodes

We experimentally study the percolation of liquid through a disordered network of liquid diodes. We focus on isotropically directed percolation, where each bond between nearest neighbor sites in a lattice may be bidirectional, unidirectional, or absent. We design and 3D-print liquid diodes, or repeating units that feature a geometrical structure, adjustable in height, which, tuned with the surface tension of the flowing liquid, determines whether the bond is bidirectional or unidirectional. Hence, for a given network, by changing the chemical composition of the liquid, a fraction of the bonds will switch behavior. We vary the fraction of absent bonds between samples, and for each sample, we vary the fraction of unidirectional bonds, and observe a percolation transition as a function of these fractions. The perfect agreement between experimental measurements and theoretical simulations demonstrates the suitability of 3D-printed liquid diodes for the study of percolation phenomena.