Control of high-resolution Electrohydrodynamic jet printing

This paper discusses a run-to-run iterative learning control (ILC) algorithm for Electrohydrodynamic jet (E-jet) printing. E-jet printing is a nano-manufacturing process that uses electric field induced fluid jet printing through nano-scale nozzles for achieving better control and resolution than traditional jet-printing processes. The printing process is controlled by changing the voltage potential between the nozzle and the substrate. However, it is difficult to maintain constant operating conditions such as stand-off height during a run of the printing process. The change in operating conditions results in fluctuating jet frequency. For stabilizing the jetting frequency across a single run, we propose a proportional ILC algorithm. We determine the jetting frequency by recording the electric current pulses when ink droplets are released from the nozzle. The frequency profile obtained from current measurements is then used to shape the voltage profile across a run to compensate for changing operating conditions. Experimental results are presented to validate the proposed control method.