Abstract
Electrohydrodynamic jet (e-jet) printing is a high-resolution additive manufacturing process that uses an electric field to extract polarizable ink from a nozzle. The high-resolution capabilities of e-jet printing are very favorable for the fabrication of printed electronics and biosensors, which is typically achieved using a highly controllable pulsating jet. In this regime, high voltage pulses are superimposed over a baseline DC voltage, which primes the meniscus for the subsequent pulse. While a higher baseline voltage reduces the response time of the system, values above a certain threshold can cause the printing to transition toward an uncontrollable jetting regime in which the natural dynamics of the ink instigate pulsating jet behavior. To characterize the effect of these unwanted transitions on the final print, key parameters of the natural pulsating jet mode must be identified. This work presents findings on the relevant time constants and volume measurements of jet printing at various subcritical voltages. While the impingement time of the jet was found to be proportional to the applied voltage, the volume of the initial droplet increasingly varied. Conclusions regarding permissible pulse widths and system predictability as a function of voltage were made.
