Reduction in buckling of deposited thin film on PDMS elastomer by engineering the substrate topology

Elastomers by granting mechanical flexibility have provided huge potential to be exploited in MEMS (Micro electro-mechanical-systems) technology. The large mismatch in thermo-mechanical properties of thin-film and elastomeric base is a major cause of buckling in the bi-layer system. The wrinkle patterns of the buckled film can cause malfunctioning or catastrophic failure of device fabricated on elastomeric base. If the underlying topology of the film is modified, the stress on bi-layer system does not remain equi-biaxial. Thus by engineering the surface topology of elastomeric substrate, the stress developed on the deposited thin film can be substantially reduced, for its meaningful applications. In the present work the planar topology of an elastomeric base (PDMS) was engineered into array of parallel ridges and it was verified with simulations and experiments that by varying the width of the ridges it is possible to control the stress magnitude below the critical value, thereby reducing the occurrence of wrinkles of the film surface over the ridge area.