Highly stretchable conductive polypyrrole film on a three dimensional porous polydimethylsiloxane surface fabricated by a simple soft lithography process

Highly stretchable conductive materials provide unique advantages for flexible electronics and many other advanced fields. In this study, we create an elastic porous polydimethylsiloxane (p-PDMS) highly stretchable conductive substrate. The p-PDMS surface is fabricated by a simple soft lithography process that replicates the 3D corrugated porous microstructures from a low-cost commercially available abrasive paper. Conductive polypyrrole (PPy) is polymerized on the p-PDMS surface by UV/Ozone (UVO) surface treatment to create the highly stretchable conductive PPy/p-PDMS film. The PPy/p-PDMS film shows a high stretchability maximum up to 80% strain. PPy/p-PDMS electrical properties based on the effects of critical PPy/p-PDMS process parameters such as UVO treatment time, deposition time, and abrasive paper grit size are evaluated in this paper. Results indicate that the highest electrical conductivity of 34.9 S m^-1 is produced from the optimized PPy/p-PDMS process conditions. Reliability testing expressed through cyclical bending and stretching of PPy/p-PDMS films, up to 1000 cycles, is also reported as good PPy/p-PDMS repeatability with maximum 5% (bending) and 36% (20% strain stretching) resistance increases after 1000 repeating cycles.