Design optimization of drug delivery nozzle based on RSM techniques

The present study elucidates the design optimization of a shock wave-assisted drug delivery nozzle to enhance the efficiency of transdermal drug delivery. The system employs a high-pressure shock wave produced from a shock tube to propel liquid drugs contained within a delivery nozzle. A solid elastic membrane separates the shock tube from the delivery nozzle chamber. This membrane undergoes an elastic deformation upon incidence of shock wave, which leads to the ejection of liquid medicine through the nozzle outlet. The geometry of the nozzle influences the behaviour of the liquid jet emanating from the nozzle outlet. Thus, optimizing the drug delivery nozzle is critical for precise dosage, homogeneous flow, and efficient targeting of medicines with minimal drug waste. Hence, optimization of the delivery nozzle geometry using response surface methodology (RSM) based on a Box-Behnken design framework is employed to achieve an optimal nozzle geometry. Multiple geometric and operational variables are systematically varied, and a desirability function is constructed to guide the optimization process. The regression analysis and maximization of the obtained second-order equation of drug ejection velocity ( V jet ) help in determining the optimum geometric parameters for the delivery nozzle. The results demonstrate that the RSM-based approach effectively identifies an optimized nozzle design. With a maximum V jet of 99.258 m/s, the optimum nozzle radius ( r d ) of 0.063 mm, the convergence angle ( θ ) of 60 o , and the length ( L d ) of 25 mm of the nozzle chamber is achieved. It clearly demonstrates the capability of the proposed RSM framework to optimize jet performance within clinically relevant velocity thresholds.