Electroactive paper (EAPap) is ordinary cotton-based paper, similar to the material used to make US bank notes, coated on each side with a thin layer of gold. The smart paper has been made by researchers from Inha University, South Korea, and Texas A & M University, US
Unlike ordinary paper, EAPap bends as a result of two effects working together. When a voltage is applied, the gold coating on one side of the paper becomes a positively charged while the other side becomes negatively charged. Sodium ions in the paper move towards the negative electrode, taking water molecules with them. This makes that side of the paper expand, causing it to bend.