The drop delay is the distance in time between the interrogation point and the droplet break-off point (Figure 1), and it determines how long the system must wait before it applies a charge once a target cell is detected.
The drop delay is reported in droplets periods, calculated as 1/droplet frequency. For example, a drop delay of 24 means that the equipment needs to wait for 24 droplet cycles before applying the electrical charge. This parameter is critical for the cell sorting performance.
Figure 1. Electrostatic sorting scheme.