Computational and experimental studies of electrospray deposition process in pharmaceutical micro-pattern formation

Electrospray deposition on a substrate through a mask is a simple (single-step) yet versatile and robust approach to generate biodegradable polymeric particle patterns. Different methods including photolithography, soft lithography and ink jetting have been employed for automated micro-pattern fabrication; however, most of them are limited to the investigation of material properties of substrates with high-cost and complex procedures. In the present work, two slightly different experimental setups were used to investigate the effect of different operational parameters in electrospray particle deposition on both mask and substrate. The sample consists of an aqueous solution of polymer, solvent and drug. In addition to the experimental section, a mathematical model was developed to track the particle trajectories and focusing effect in electrospray deposition process on the substrate.The final results confirm that the clearest particle pattern and the best focusing effect on the substrate can be achieved with long distance between the nozzle and the substrate, high voltage difference between the nozzle and the mask, short process time and low solution flow rate. On the contrary, a smooth and integrated layer on the mask can be formed with a short distance between the nozzle and substrate in which no clear pattern can be recognized. Furthermore, micro-fibers can be observed on the mask when the voltage difference between the nozzle and substrate is not high.

► We have presented a comprehensive study which includes the most important operational parameters on the electrospray deposition in pharmaceutical processes.
► A finite-element model was developed to track the particle trajectories in electrospray deposition process for particle patterning.
► Factors affecting the clearance of the pattern and the density of particle patterning were analyzed theoretically and experimentally.
► The best particle pattern was obtained with high voltage difference and low solution flow rate.
► Short distance between nozzle and substrate and high voltage difference enhances particle deposition efficiency.