Fabrication of patterned polypyrrole on fluoropolymers for pH sensing applications

Patterns of polypyrrole (PPy) have been fabricated on flexible poly(tetrafluoroethylene) (PTFE) films using a combination of micro-contact printing, electroless deposition of copper and electropolymerisation of pyrrole. A patterned elastomeric stamp was used to deliver a nitrogen-containing silane coupling agent to an argon plasma-pretreated PTFE surface. The surface was subsequently activated by PdCl2 and immersed in an electroless copper plating bath allowing selective metallisation. Electropolymerisation of pyrrole was performed on copper-patterned PTFE resulting in the formation of micrometer-scale PPy structures. Each modification and deposition step was characterised by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Potentiometric measurements have demonstrated that PPy-patterned PTFE has potential application as a pH sensor. The response times of the sensors have also been investigated. This study offers an interesting alternative to conventional polymer-based pH sensors in terms of production and mechanical support.