PDMS elastomer (Sylgard 184) and the curing agent were procured from Dow Corning Corp. Method of preparation of microchannels embedded inside PDMS layer: Microchannels of different diameter were embedded inside PDMS films by the method described previously . Briefly, PDMS oligomer, mixed with the curing agent at 10:1 w/w ratio was dispensed on a plasma oxidized glass slide. Steel rods of diameter 450-550 m, used as templates, were then placed horizontally on this slide inside the pool of liquid. An OTS coated glass plate was placed on this liquid pool such that the liquid remained confined between the two parallel plates, with the gap between them maintained by using two spacers of specific thickness placed in-between. The liquid was crosslinked for 72 hours at 24 o C which. Preliminary experiments suggested that crosslinking of the film for a smaller duration: for 48-24 hours, led to its partial curing, because of which, the film underwent undesired deformation and rupture during removal of the template. Films cured at this condition were found to have Young's modulus of 1.25 E  MPa (Figure ) which was small enough to allow probing of the elasto-capillarity induced deformation, yet was large enough to render sufficient mechanical integrity to the material. The steel rods were gently removed and the channel surface was cleaned with aqueous solution of Ethanol (aqEth) and degassed water and was blow dried with Nitrogen. Fig. shows the schematic of a typical channel-embedded layer. It shows also the magnified view of the lateral cross-section of the film. The thickness, h of the PDMS layer was maintained slightly larger than the channel diameter, d with minimum wall thickness, 0 t h d   , varied from 5-66 m.