Plasma surface activation and TiN coating of a TPV substrate for biomedical applications

Abstract

A thermoplastic vulcanizate (TPV) substrate was coated with a thin conductive film of titanium nitride (TiN), by dc reactive sputtering, aiming to develop polymer-based electrodes for bio-signal acquisition, namely for electroencephalographic (EEG) and electrocardiographic (ECG) applications. After the preparation process, TPVs were characterized in terms of their mechanical and surface properties. A detailed experimental protocol was followed in order to improve the adhesion of the film, consisting of a three-stage plasma treatment in an argon atmosphere. The electrochemical properties of the coated samples were studied in synthetic sweat solutions by open circuit potential (OCP) measurements and electrochemical impedance spectroscopy (EIS). The results showed that the surface plasma treated TPV with a 60% EPDM and 40% PP composition coated with a nanometric TiN film exhibited good mechanical properties and electrochemical behavior, according to the main requirements of an electrode to be used in common EEG and ECG exams.