Pouya Firuzy Rad, Hamed Ghafarirad, Seyed Mahdi Rezaei,
Volume 24, Issue 10 (October 2024)
Abstract
In this study, a droplet injection system based on a piezoelectric actuator was designed and built to evaluate the system's performance in producing droplets of varying volumes. Droplet injection systems are crucial in many biological and biomedical applications. These systems contain numerous adjustable parameters, making it challenging to predict the resulting droplet volume. To analyze the influence of different input parameters and predict droplet volume, a statistical design of experiments approach was employed using response Surface methodology. Five main factors were investigated in this research, including three parameters related to the input signal (rise time, fall time, open time, and signal amplitude), back pressure, and nozzle diameter. Different levels were considered for each parameter, and their independent and interactive effects on droplet volume were analyzed. The results indicated that all factors had a p-value of less than 0.05, confirming their significant impact on the output volume. The regression model obtained, with R2 of 0.98, showed strong predictive capability for droplet volume. Furthermore, the inverse performance of the regression model was analyzed using parameter optimization, and a comparison with the experimental setup demonstrated an error of less than 5%. This model enables the optimization of design parameters and enhances the system's performance, significantly improving the accuracy and efficiency of such devices in targeted applications
Amir Hossein Moradi, Hamed Ghafarirad, Seyed Mehdi Rezaei, Mohammad Zareinejad, Pouya Firuzy Rad,
Volume 24, Issue 10 (October 2024)
Abstract
This article focuses on the design, manufacturing, and dynamic modeling of a piezoelectric pneumatic servo valve based on a compliant mechanism. The use of piezoelectric actuators in these valves, due to their fast dynamic response and high precision, significantly improves the speed of pressure control. To this end, the structure of the pneumatic servo valve and the function of its components were initially investigated. To enhance the valve's orifice opening, a rhombus type compliant mechanism was designed to amplify the displacement range of the piezoelectric actuator. Subsequently, a comprehensive dynamic model of the system was presented. After identification and validating the proposed dynamics, the results of air pressure control for both steady and time-varying reference inputs were provided. Experimental results indicate that the proposed dynamic model for the manufactured valve has a maximum error of 25%. Additionally, frequency analysis results show that the valve has a dynamic bandwidth of 90 Hz and a natural frequency of 56 Hz, highlighting its applicability for high-frequency operations. The results of pressure control demonstrate a step response time of approximately 21 milliseconds at a pressure of 2 bar, indicating its capability to respond to rapid pressure changes. Furthermore, the ability to track input pressures with varying frequencies and amplitudes was also evaluated
