A printing device comprising print heads having discharging elements arranged in linear array and a control method thereof is disclosed enabling to overcome or at least reduce the visibility to the human eye of systematic image dot-size variations, i. The operation of these devices may facilitate restoring conductivity of neural signals or responses within severed or damaged nerve cells. The drive applies voltage signals to the squeezers and monitors one or more of a voltage across the squeezer, a capacitance change with the fiber, a force applied to the squeezer, a force applied to the fiber, and a resonance of one or more squeezers.