Comparison of different modifications of screen-printed working electrodes of electrochemical sensors using carbon nanotubes and plasma treatment

Abstract

The screen-printed working electrode (WE) of an electrochemical sensor was modified with multi-walled carbon nanotubes (MWCNTs) and a plasma treatment. The plasma treatment was performed using radio frequency capacitively coupled discharge in Ar/O2, Ar/cyclopropylamine and Ar/NH3. The surface of the WEs was characterized by scanning electron microscopy and their electrochemical behaviours were studied using potassium ferro/ferricyanide and dopamine as standard electrochemical probes. The most promising results were obtained with the electrodes modified by oxygen plasma because the reversibility and the current response were both improved significantly. The peak-to-peak separation improved from 879 to 116 mV after the oxygen plasma treatment of the bare DuPont 7102 electrode. Spray-coated MWCNTs had a positive effect on the performance of the screen-printed DuPont 7102 WE if the sprayed MWCNTs layer was thicker. However, this improvement did not reach the performance of the screen-printed DuPont electrode modified by plasma oxidation. The modification by Ar/NH3 had weak influence on the response depending on the type of the electrode and plasma treatment in Ar/cyclopropylamine plasma led to an inhibition of the electrochemical reactivity due to a preparation of too thick insulating film. MWCNTs modified screen-printed disposable electrochemical microsensor for trace detection of various substances in a droplet.