Steady Cone-Jet Mode of Electrospray for Single-Cell Deposition

We propose using the electrospray cone-jet mode operated near its minimum-flow-rate stability limit for single-cell deposition. Because the jet is much thinner than the cells themselves, individual cells can be clearly visualized or detected during deposition. At such low flow rates, individual cells could potentially be placed at distinct, user-defined locations, even at relatively high cell concentrations. In this sense, our approach provides a spatial resolution at the scale of a single cell. We demonstrate the method's capabilities by depositing cells onto a millimeter-scale droplet of a standard cell-culture medium. Cell viability assays indicate that many cells maintain membrane integrity after exposure to the electrosprayed liquid, suggesting that the process can preserve cell integrity in a substantial fraction of cells under the tested conditions.