V-PAM assisted rapid biofluid filling in irregular microfluidic geometries with dead-end channels. (a) Original photo of leaf venation. Photo permission of SmugMug, Inc. (b) Microfluidic leaf patterns and V-PAM vacuum channels were filled with blue and maize dye solutions, respectively, for visualization. (c) Bright field images showing rapid filling of a green dye solution in microfluidic leaf patterns with V-PAM activated. P: 2 psi. (d) Original image depicting the human blood circulation system. Note red and blue vessels correspond to arterial and venous systems, respectively. Image courtesy of the Access Excellence, National Health Museum. (e) Microfluidic human (µMan) chip filled with red and blue dye solutions to visualize the vessel and V-PAM pattern, respectively. (f) Bright field images showing rapid filling of the µMan chip with blue and maize solutions through two inlets at two palms. P: 12.5 psi. In all cases, S: 1.6 krpm, and V: 12.5 psi.