Three Dimensional Transient Multifield Analysis of a Piezoelectric Micropump for Drug Delivery System for Treatment of Hemodynamic Dysfunctions

Abstract

In this paper, we present design of a transdermal drug delivery system for treatment of cardiovascular or hemodynamic disorders such as hypertension. The system comprises of integrated control electronics and microelectromechanical system devices such as micropump, micro blood pressure sensor and microneedle array. The objective is to overcome the limitations of oral therapy such as variable absorption profile and the need for frequent dosing, by fabricating a safe, reliable and cost effective transdermal drug delivery system to dispense various pharmacological agents through the skin for treatment of hemodynamic dysfunction such as hypertension. Moreover, design optimization of a piezoelectrically actuated valveless micropump is presented for the drug delivery system. Because of the complexity in analysis of piezoelectric micropump, which involves structural and fluid field couplings in a complicated geometrical arrangement, finite element (FE) numerical simulation rather than an analytical system has been used. The behavior of the piezoelectric actuator with biocompatible polydimethylsiloxane membrane is first studied by conducting piezoelectric analysis. Then the performance of the valveless micropump is analyzed by building a three dimensional electric-solid-fluid model of the micropump. The effect of geometrical dimensions on micropump characteristics and efficiency of nozzle/diffuser elements of a valveless micropump is investigated in the transient analysis using multiple code coupling method. The deformation results of the membrane using multifield code coupling analysis are in good agreement with analytical as well as results of single code coupling analysis of a piezoelectric micropump. The analysis predicts that to enhance the performance of the micropump, diffuser geometrical dimensions such as diffuser length, diffuser neck width and diffuser angle need to be optimized. Micropump flow rate is not strongly affected at low excitation frequencies from 10 to 200 Hz. The excitation voltage is the more dominant factor that affects the flow rate of the micropump as compared with the excitation frequency. However, at extremely high excitation frequencies beyond 8,000 Hz, the flow rate drops as the membrane exhibits multiple bending peaks which is not desirable for fluid flow. Following the extensive numerical analysis, actual fabrication and performance characterization of the micropump is presented. The performance of the micropump is characterized in terms of piezoelectric actuator deflection and micropump flow rate at different operational parameters. The set of multifield simulations and experimental measurement of deflection and flow rate at varying voltage and excitation frequency is a significant advance in the study of the electric-solid-fluid coupled field effects as it allows transient, three dimensional piezoelectric and fluid analysis of the micropump thereby facilitating a more realistic multifield analysis. The results of the present study will also help to conduct relevant strength duration te...

Design, Fabrication and Analysis of Silicon Hollow Microneedles for Transdermal Drug Delivery System for Treatment of Hemodynamic Dysfunctions

“…In our previous study we presented the design of a controlled drug delivery system for the treatment of cardiovascular or hemodynamic disorders such as hypertension (Nisar et al 2008). In this work we present design and fabrication of hollow out-of-plane silicon microneedles to integrate with previously fabricated piezoelectrically actuated valveless micropump (Nisar et al 2008).…”

“…In this work we present design and fabrication of hollow out-of-plane silicon microneedles to integrate with previously fabricated piezoelectrically actuated valveless micropump (Nisar et al 2008). All the numerical studies reported in literature on the design and analysis of silicon microneedles cover either structural or fluid analysis only.…”

Multifield analysis of a piezoelectric valveless micropump: effects of actuation frequency and electric potential

“…The mass flow rate is provided per unit depth of the device (a two-dimensional model is considered). While the previous studies [2,4,6,7,10,18,19] report on the maximum value of instantaneous flow rates, instantaneous velocities are integrated along the outlet at each time step during one perturbation cycle in the present study. The instantaneous flow rates can be adjusted by varying parameters such as applied electric potential, actuation frequency, and geometric variables.…”

Pump Design for a Portable Renal Replacement System

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“…From this equation, the current that is required to contract the Flexinol during the given contraction time can be calculated. V required V = current × resistance (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) No. of Flexinol/finger refers to number of Flexinols that should be connected to each finger.…”