Electrical Detection and Ejection of Beads in a One-Cell-Per-Drop Microdispenser

We present developments on a one-cell-per-drop microdispenser for cell-based assays. This device has been designed to detect individual cells inside a microfluidic channel and eject them in nanoliter-size droplets with the advantage of dispensing a precise number of cells at a given spot on a receptor slide. Detection of beads or cells is based on the electrical measurement of a small section of the microfluidic channel. The detection triggers the opening of a valve and consequently the ejection of a droplet containing the cell. We demonstrate electrical detection and controlled ejection of beads, and we introduce the dispenser robot for arraying of cell-containing droplets.