Abstract
In this study, a hybridized neuro-genetic optimization methodology realized by embedding numerical simulations trained artificial neural networks (ANN) into a genetic algorithm (GA) is used to optimize the flow rectification efficiency of the diffuser element for a valveless diaphragm micropump application. A higher efficiency ratio of the diffuser element consequently yields a higher flow rate for the micropump. For that purpose, optimization of the diffuser element is essential to determine the maximum pumping rate that the micropump is able to generate. Numerical simulations are initially carried out using CoventorWare® to analyze the effects of varying parameters such as diffuser angle, Reynolds number and aspect ratio on the volumetric flow rate of the micropump. A limited range of simulation results will then be used to train the neural network via back-propagation algorithm and optimization process commence subsequently by embedding the trained ANN results as a fitness function into GA. The objective of the optimization is to maximize the efficiency ratio of the diffuser element for the range of parameters investigated. The optimized efficiency ratio obtained from the neuro-genetic optimization is 1.38, which is higher than any of the maximum efficiency ratio attained from the overall parametric studies, establishing the superiority of the optimization method.
Highlights
In recent developments, micropumps utilizing piezoelectric actuation have been commonly employed for directing the fluid purposes especially in BioMEMS and microfluidic systems [1,2,3,4,5,6].One of the essential features of micropump is the ability to direct the fluid flow as to flow in only one direction and this could be enhanced with the introduction of a check valve
Results of the volumetric net flow rate at the throat of the diffuser element obtained from CoventorWare® simulations for different diffuser angle is presented in Figure 6 while Figure 7 and Figure 8 shows the efficiency ratio of the diffuser element for variations in Reynolds number and aspect ratio
The efficiency ratio of the diffuser element has been successfully optimized for valveless diaphragm micropump applications
Summary
Micropumps utilizing piezoelectric actuation have been commonly employed for directing the fluid purposes especially in BioMEMS and microfluidic systems [1,2,3,4,5,6].One of the essential features of micropump is the ability to direct the fluid flow as to flow in only one direction and this could be enhanced with the introduction of a check valve. The earliest concept of valveless micropumps incorporating diffuser elements have been developed [8,9] with the hopes of eliminating the additional voltage requirement for operating the check valves while at the same time, improve the reliability aspect of the micropump since no mechanical moving parts are involved. It was not until 1997 that the first valveless diffuser micropump in silicon was introduced by Olsson et al [11], which subsequently led to great interest on diffuser elements for applications in micropumps
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