Electrohydrodynamic “drop-and-place” particle deployment

The “drop-and-place” paradigm aims at delivering and positioning liquid drops using a pulsed electrohydrodynamic jet. On-demand drops much smaller than the diameter of the delivery nozzle may also contain particles. We report proof-of-concept experiments on the delivery of single 2μm diameter particles using a 50μm nozzle and identify the control parameters for dosing and positioning accuracies. A positioning accuracy at the micrometer level is achieved by eliminating contact line pinning on a hydrophobic surface and minimizing impingement-induced motion. The dosing statistics follow the random Poisson distribution, indicating that single-particle accuracy can be achieved using a gating mechanism.