Current characteristic signals of aqueous solution transferring through microfluidic channel under non-continuous DC electric field

Abstract

The surface effect is becoming apparently significant as the miniaturization of fluidic devices. In the micro/nanochannel fluidics, 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 non-continuous DC electric field force, the characteristics of current signals of the fluid transferring through microfluidic channel are systematically studied. Six modes of current signal are summarized, and some new significant phenomena are found, e.g. there exists a critical voltage at which the steady current value equals to zero; the absolute value of the steady current decreases at first, however, it increases with the external voltage greater than the critical voltage as the electrode area ratio of cathode and anode is 10 and 20; the critical voltage increases with the enhancing of electrode area ratio of cathode and anode and solution pH, while it decreases with the raising of ion concentration. Finally, the microscopic mechanism of the electrode surface charge effects is discussed preliminarily. The rules will be helpful for detecting and manipulating single biomolecules in the micro/nanofluidic chips and biosensors.

Molecular dynamics simulation of graphene-based thin films for seawater desalination

“…results demonstrate that the λd increases when the feed salinity C decreases, in agreement with the previously reported results [284,285].…”

Effect of Mono- and Divalent Metal Ions on Current–Voltage Features of a λ-DNA Solution Electrically Driven in a Microfluidic Capillary

“…One possible explanation is that the crowding effect inhibits the actual C i or b i of the charged species, which in turn leads to a smaller g m . I s,0 and the jump in g m could be attributed to the different polarizations on the anode and cathode of different areas . Because the reaction areas of the solution with the anode or cathode are different, different numbers of free charges emerge on the two electrodes and show different polarization strengths.…”

“…All electrodes were made of platinum and wrapped with a 2 mm thick PTFE layer on the side surface. This setup reduced the recovery time of the detector’s current response and improved the stability of the measurements …”

“…28 The anode [working electrode (W)] and an additional reference electrode [reference electrode (R)] were inserted into the cis chamber, and the cathode [counter electrode (C)] was placed in the trans chamber. The surface area of the counter electrode was 20 times larger than that of the working electrode, 29 i.e., asymmetric electrodes. All electrodes were made of platinum and wrapped with a 2 mm thick PTFE layer on the side surface.…”

“…This setup reduced the recovery time of the detector's current response and improved the stability of the measurements. 29 A precision potentiostat (EA162, eDAQ) was employed to provide an accurate and stable voltage. We used a microcurrent detector (EA 162, e-corder 401, eDAQ) with high precision and sensitivity to monitor the current in the capillary.…”