Effect of the detector parameters on the sensitivity of contactless conductivity detector for microchip electrophoresis

The contactless conductivity has attained great attention in the last decade. But the application of contactless conductivity is restricted by its sensitivity, how to improve the sensitivity has become the key of contactless conductivity. Some simple equivalent circuits have been used to explain the basic functioning of a capacitively coupled contactless conductivity detector, it can not explain some experiment phenomena. A new equivalent circuit of the cell is given in this paper according the physical structure of cell, which takes into account the effects of the spatial component of the solution conductivity as the electrophoretic zones pass inside the detector. The effect of the detector geometry on the sensitivity of contactless conductivity is studied. By simulation, the optimal parameters were found. This paper has guidance to improve the sensitivity of contactless conductivity.