Reversal current observed in micro- and submicro-channel flow under non-continuous DC electric field

Abstract

In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate and analyze the characteristics of single bio-molecules. To accurately and flexibly control the movement of single molecule within micro-/submicro-fluidic channels, the characteristics of current signals at the initial stage of the flow are systematically studied based on a three-electrode system. The current response of micro-/submicro-fluidic channels filled with different electrolyte solutions in non-continuous external electric field are investigated. It is found, there always exists a current reversal phenomenon, which is an inherent property of the current signals in micro/submicro-fluidics Each solution has an individual critical voltage under which the steady current value is equal to zero The interaction between the steady current and external applied voltage follows an exponential function. All these results can be attributed to the overpotentials of the electric double layer on the electrodes. These results are helpful for the design and fabrication of functional micro/nano-scale fluidic sensors and biochips.

Effect of mono-/divalent metal ions on the conductivity characteristics of DNA solutions transferring through a microfluidic channel

“…Duan et al found that utilization of this three-electrode system reduces the recovery time in the current response of the detector, and improves the stability of the measurements. [17,18,21] Moreover, this integrated system was fixed in a grounded Faraday cage to shield external electromagnetic interference. The potentiostat could provide external voltages ranging from −10 V to 10 V with an accuracy of 1 µV, which was connected to the electrodes to provide stable and accurate voltage.…”

“…Previous studies have found that there are several factors that affect the electrical characteristics of mixed solutions of DNA and metal ions as they pass through a micro-/nanochannel, such as the concentration and PH values of the electrolyte, the material and inner diameter of the micro-/nanochannel, etc. [17][18][19] Further research indicates that the interaction between DNA molecules and metal ions promotes or inhibits the concentration or mobility of the charged particles in the mixed solution, leading to different electrical characteristics, [20] however, how the interaction works remains unclear.…”