This study demonstrates that the Marangoni flow in a channel network can solve maze
problems such as exploring and visualizing the shortest path and finding all possible
solutions in a parallel fashion. The Marangoni flow is generated by the pH gradient in a
maze filled with an alkaline solution of a fatty acid by introducing a hydrogel block soaked
with an acid at the exit. The pH gradient changes the protonation rate of fatty acid molecules,
which translates into the surface tension gradient at the liquid–air interface through the …