Effect Of Electrode Surface Charge Effect On Micro - Flow Control Current Signal Detection

The surface charge effect is becoming apparently significant as the miniaturization of micro/nano-fluidic devices. In the micro/nanochannel fluidics, compared to the channel surface charge effects, the electrode surface effects have the same important influence on the current signals as the channel surface effects. In this paper, when aqueous solution are driven with external electric field force, the characteristics of current signals of the fluid transferring through microfluidic channel are systematically studied. Main contents and achievements are summerized as follows,(1) The current response has a start-up peak and then decays with time until reach a steady state. This can be explained by the interaction of EDL and overpotential.(2) Six modes of current signal are summarized. The probabilities of the positive current signal is larger than that of the corresponding negative current signal, and the probabilities of any special current signals increase with the channel diameter enlarging.(3) The current response reversed with the increase of voltage when the effective area of the auxiliary electrode larger than the working electrode, this is due to the competition effect of the external electrical field and the screening field.(4) The critical voltage of the current response reversal increases with the enhancing of electrode area ratio of cathode and anode and solution pH, while it decreases with the raising of ion concentration.(5) It was found that the three electrodes systerm can significantly decreases the critical voltage and recovery time.These results are helpful to accurately analyze the current characteristics in micro/nanochannel fluidics, and hold a great deal of potential for further miniaturization and precision of micro/nanofluidic devices.