Electrical separation and detection
Capillary electrophoresis is a separation technique that has been very successful in the analysis of DNA fragments and other biomolecules.
In capillary electrophoresis, small amounts of fluids are injected into a separation channel by using plug injection. Substances are separated based on their electrophoretic mobility, which is proportional to their charge to size ratio.
Fast separation by CE
Capillary electrophoresis with microfluidic chips offers advantages over traditional CE. Having an integrated injection structure enables injection of much smaller volumes than would be possible in standard CE. This means the separation channels can be very short (a few centimeters) for certain applications, which results in much faster analysis. An additional advantage of using chips is that the detection can be integrated in the chip.
Electrochemical Impedance Spectroscopy (EIS) Chip
The use of electrochemical impedance spectroscopy (EIS) as an inline monitoring system for the accurate detection and counting of droplets, cells or particles has now been realized in a single compact microfluidic chip. The EIS chip (figure 1) is designed to give accurate detection as particles or cells pass between the out-of-plane electrodes. These specially designed out-of-plane electrodes (figure 2B) achieve a more parallel and uniform electric field when compared to in-plane electrodes (figure 2A). This increased field uniformity enables better particle detection by data acquistion systems, such as those designed by our development partner Zurich Instruments. Additional stability to the inline monitoring is enabled by Fluigent’s accurate flow control systems. Micronit has also developed an interfacing system (figure 3) based on the Fluidic Connect Pro platform, featuring both fluidic and electrical interfacing to the chip.