All-3D Printed Microelectrodes

In this work, microelectrodes were prepared entirely by the fused deposition modeling 3D printing method. The obtained systems were characterized with good reproducibility in terms of electrode area and electrochemical performance typical for microelectrodes. Application of 3D-printed microelectrodes in voltammetric pH sensing, postmodification with redox-active, pH-dependent reagent syringaldazine, highlights the effect of electrode housing materials. It is clearly shown that application of poly(lactic acid), the most common polymer used for preparation of electrochemical sensors using the 3D printing approach, results in local stabilization of the pH close to the microelectrode. This effect results from spontaneous hydrolysis of poly(lactic acid) and formation of products locally buffering pH or partially blocking the electrode active surface. Thus, to prepare miniature pH voltammetric sensors, a glycol-modified polyethylene terephthalate filament was used to prepare microelectrode housing. The obtained microelectrode sensors were characterized with a linear Nernstian dependence of the redox peak positions on pH within the range from 9 to 3.