An integrated cell counting and continuous cell lysis device using an optically induced electric field

This paper reports an integrated microfluidic device capable of performing online cell counting and continuous cell lysis by using an electric field induced by projected optical images. This device can be used to quantify the number of lysed cells, which is essential for molecular diagnosis. First, cells are hydrodynamically focused in the middle of a channel and then are counted using a pair of buried optical fibers. After cell counting, a projected optical image is used to induce an electric field, which arises from the use of a photoconductive material deposited on an indium-tin-oxide substrate. The cells can be lysed continuously due to the generation of a transmembrane potential. For cell counting, a total of 97 fibroblast cells have been perfectly counted without any miscounts. The optically induced electric field can be easily fine-tuned by adjusting the exposure time and the illumination power intensity. Experimental data showed 93.8% cells (45 out of 48 cells) are successfully lysed when they passed the projected optical patterns at an applied voltage of 7 Vpp and an illuminated power density of 100 kW/m2. The development of this integrated device provides a promising tool for a variety of applications for cell-based analysis and molecular diagnosis.