Integration of ring nanoelectrodes into microwell for the bioelectrochemical analysis in sub-picoliter volumes

We report here the fabrication and the electrochemical characterization of recessed ring nanoelectrodes (RNE) integrated in microwell arrays. Such configuration has all advantages of microelectrodes arrays but is more suitable for electrochemical analysis in sub-picoliter volumes. The technological process based on the reactive ion etching of a SiO₂/Ti/Pt/Ti/SiO₂ stacking is optimized in order to develop for the first time functional electrochemical microdevices on glass substrate. Electrochemical characterizations are finally conducted in order to study the amperometric behavior of recessed ring nanoelectrodes and to define design rules for optimizing the electrochemical detection properties of RNE-based microwell arrays. Finally, a “generation - collection mode” approach is proposed to define the effective collection factor of RNE into microwell. All these results demonstrate that recessed ring nanoelectrode arrays are fitted to the statistic analysis of single cells and to the detection of electrochemical species at the nanoscale.