Femtoliter and attoliter electrochemical cells on chips

Chip electrochemistry is one of the top ambitions of today's electrochemistry. Here, a study for manufacturing electrochemical microcells on chips in a cost-effective, facile, and mass-producible way is presented. The ultrasmall, planar electrochemical cells, ranging from 140 femtoliter to 14 attoliter, can work independently as electroanalytical devices with embedded functional microelectrodes. Electrochemical responses of the miniaturized cells have been characterized by cyclic voltammetry. Ideal steady-state voltammograms were recorded with femtoliter volume cells, indicating the domination of a radical diffusion regime and a greatly improved signal/background ratio. Quasi-thin-layer behavior was observed for attoliter volume cells, which exhibited a special capability of offering accurately confined domains for redox processes. Positive feedback effect of the cells indicated that interactions between the close-by working and reference/counter microelectrodes can be well developed and potentially utilized for trace level electroanalysis. This study vividly offers i) a new protocol of electrochemical chip for applications, ii) a new tool for trace electroanalysis, and iii) a more approachable insight for single molecule electrochemistry in the near future.