Wrinkles in platinum layers are affected by changes to the polymer substrate before deposition, according to researchers in Japan. 

When a layer of platinum is deposited on polydimethylsiloxane (PDMS), wrinkles form spontaneously. Takuya Ohzono and colleagues from RIKEN and Hokkaido University patterned a PDMS surface, before the platinum was deposited, using adhered polystyrene microspheres, and showed how wrinkles are influenced by those patterns.  

The microspheres act as a mask when the exposed surface is treated with oxygen plasma. When they are removed, by rinsing in benzene, ring-like ridges are seen. When platinum is then deposited onto this pre-treated PDMS, different wrinkle patterns form. These wrinkles depend on the size of the microspheres. 

Ohzono hopes this method of making polymer patterns on a substrate at the sub-micrometre scale will prove useful for technological applications that require precision, such as substrates for tissue growth or microfluidic channels.  

Caroline Moore