Multiple-frequency impedance measurements in continuous flow for automated evaluation of yeast cell lysis

This paper reports on an electrical lysis device integrating multiple-frequency impedance measurements for automated evaluation of the lysis efficiency and counting of the lysed cells. Conventional techniques use chemical reagents to dissolve the cell membrane, causing unwanted interference with possible intracellular content analysis downstream. Conversely, electrical lysis does not use reagents but electrical fields to disrupt the membrane, and is easy to integrate with microfabrication techniques. Besides, yeast cell lysis is difficult to evaluate, as it induces no significant visual difference. The presented device uses an innovative approach allowing automated evaluation of the lysis efficiency in continuous flow by multiple-frequency impedance measurements. This technique is able to count and differentiate living and dead cells without optical setup, providing an estimation of the sample viability after lysis. Counting the cells effectively lysed is essential for downstream analysis in order to provide an estimate of the analyte concentration per cell. The lysis is performed using AC electrical fields and so-called liquid electrodes, leading to an efficiency of 98%. (C) 2010 Elsevier B.V. All rights reserved.