S. Revathi

Bio: S. Revathi is an academic researcher from VIT University. The author has contributed to research in topics: Micropump & Diffuser (thermodynamics). The author has an hindex of 4, co-authored 6 publications receiving 33 citations.

Design and Development of Piezoelectric Composite-Based Micropump

Abstract: Valveless micropumps are extensively used in micro fluidic systems, including health care monitoring and diagnostic devices, computer devices, and so on, as it forms the critical component in the microsystem for precise and controlled fluid handling. This paper proposes the design and development of a novel, significantly low cost, planar micropump with piezoelectric polymer composite, consisting of lead zirconate titanate and polyvinylidene fluoride, for actuation. The novelty lies in the synthesis and use of the piezoelectric polymer composite as the actuating mechanism and the diffuser/nozzle design around the line of appreciable stall to achieve maximum flow rate for the given boundary conditions. The parametric study on the micropump geometry, including, chamber depth and diameter as well as diffuser/nozzle was carried out by using numerical simulations in COMSOL multiphysics, to analyze the fluid flow rate. The response of piezoelectric polymer to the applied sinusoidal voltage causes flow rectification in the micropump. An aspect ratio (diffuser length/diffuser width) of 15 produces maximum fluid flow rate. The designed micropump can achieve maximum fluid flow rate at low applied voltage and frequency of operation. [2018-0166]

Synthesis, Structural, Optical and Dielectric Properties of Nanostructured 0-3 PZT/PVDF Composite Films.

Abstract: Nanostructured PbZr0.52Ti0.48O3 (PZT) powder was synthesized at 500 °C-800 °C using sol-gel route. X-ray diffraction and Rietveld analysis confirmed the formation of perovskite structure. The sample heat treated at 800 °C alone showed the formation of morphotropic phase boundary with coexistence of tetragonal and rhombohedral phase. The PZT powder and PVDF were used in 0-3 connectivity to form the PZT/PVDF composite film using solvent casting method. The composite films containing 10%, 50%, 70% and 80% volume fraction of PZT in PVDF were fabricated. The XRD spectra validated that the PZT structure remains unaltered in the composites and was not affected by the presence of PVDF. The scanning electron microscopy images show good degree of dispersion of PZT in PVDF matrix and the formation of pores at higher PZT loading. The quantitative analysis of elements and their composition were confirmed from energy dispersive X-ray analysis. The optical band gap of the PVDF film is 3.3 eV and the band gap decreased with increase in volume fraction of PZT fillers. The FTIR spectra showed the bands corresponding to different phases of PVDF (α, β, γ) and perovskite phase of PZT. The thermogravimetric analysis showed that PZT/PVDF composite films showed better thermal stability than the pure PVDF film and hydrophobicity. The dielectric constant was measured at frequency ranging from 1 Hz to 6 MHz and for temperature ranging from room temperature to 150 °C. The composite with 50% PZT filler loading shows the maximum dielectric constant at the studied frequency and temperature range with flexibility.

A design analysis of piezoelectric-polymer composite-based valveless micropump

Abstract: This paper presents the three-dimensional numerical simulation of a micropump, including diffuser and analytical modelling of the micropump flow rate. The numerical simulation of the diffuser is pe...

Study of the effect on flow rate for planar type polymer-based diaphragm piezoelectric actuated valveless micropump for insulin delivery

Abstract: Micro-electromechanical systems are electrically sensed and actuated mechanical devices that are in micrometre-sized overall dimensions. The microsize of the system enables it to be used in several critical applications including healthcare where the system performance can be precisely controlled. One such application is micropump for drug delivery. Micropumps can be either valve based or valveless. Valve-based micropumps have mechanical check valves to control and deliver drugs through flaps or membranes. In valveless micropumps, the control is made through a diffuser/nozzle arrangement which regulates the liquid flow rate. In this paper, a valveless insulin pump based on piezoelectric actuation made of polymer-based material as diaphragm in planar type is constructed and the dependency of flow rate with material properties and size is studied. The modelling of the pump is carried out using COMSOL Multiphysics by coupling fluid structure interaction (fsi) and piezoelectric (pzd) physics module. T...

Analytical modelling and numerical simulation of 0–3 PZT/PVDF composite actuated micropump

Abstract: In this paper the flow characteristic of laminar flow through planar diffuser was studied for different flow regime and its geometry, including angle, length and width were optimized. The diffuser ...

Piezoelectric micropumps: state of the art review

Abstract: The purpose of this paper is to present an overview of problems and some research gaps for better understanding of piezoelectric micropump studies. Micropumps have important and diverse application areas in health and engineering applications. In recent years, researchers have carried out simulations, analytical and experimental studies to develop these technologies with different methods for the same purpose. It has been determined that piezoelectric micropumps as MEMS devices have an effective deep interest. It is worth mentioning that piezoelectric material has been considered by researchers as an attractive actuator due to its high-performance, potential cost and design convenience. This paper comprehensively reviews the studies that bring innovations in the literature of piezoelectric micropumps. Analytical characterization and modeling procedures studied by various scientists in the field of the piezoelectric actuators are also presented in detail. The analytical section will mainly focus on the studies related to the static and dynamic behaviours of circular piezoelectric actuators. Moreover, the advantages and disadvantages of the various components used to fabricate micropumps have been investigated according to the available information in the literature. Consequently, this review enables researchers a useful reference on piezoelectric micropump parameters such as modeling, flow rate, shape control, geometry, and size optimization for key engineering applications.

3-D Design and Simulation of a Piezoelectric Micropump

Abstract: The objective of this paper is to carefully study the performances of a new piezoelectric micropump that could be used, e.g., for drug delivery or micro-cooling systems. The proposed micropump is characterized by silicon diaphragms, with a piezoelectric actuation at a 60 V input voltage, and by two passive valves for flow input and output. By means of a 3-D Finite Element (FE) model, the fluid dynamic response during different stages of the working cycle is investigated, together with the fluid-structure interaction. The maximum predicted outflow is 1.62 μL min - 1 , obtained at 10 Hz working frequency. The computational model enables the optimization of geometrical features, with the goal to improve the pumping efficiency: The outflow is increased until 2.5 μL min - 1 .

Design and optimization of MEMS based piezoelectric actuator for drug delivery systems

Abstract: In this paper, piezoelectric principle based an actuator is design for a micropump, which is suitable for drug delivery systems. The natural frequency and stress analysis have been performed to determine the reliability of the device in terms of minimum safety factor. We have observed the uniform deflections of the actuators by varying the thicknesses of the piezoelectric layer of the actuator. The design of the actuators is considered in circular and rectangular geometry. The materials are selected appropriately such that the component is biocompatible and can be used in biomedical applications. Among the various considerations made on dimensions and geometry, it is observed that the circular piezoelectric actuator undergoes a high displacement of 2950 μm at an infinitesimal thickness of 0.1 μm. At minimum safety factor of one, the maximum stress and voltage the actuator can hold is 596 GPa and 8500 V respectively.

Fully coupled modeling and design of a piezoelectric actuation based valveless micropump for drug delivery application

Abstract: The precise control over the drug delivery involved in several vital applications including healthcare is required for achieving a therapeutic effect. For such precise control/manipulation of the drugs, micropumps are used. These micropumps are basically of two types viz. check valve-based and valveless micropumps. The valveless micropumps are preferable due to the congestion-free operation of diffuser/nozzle valves. In this paper, design optimization of a valveless piezo-electric actuation based micropump is carried out using COMSOL Multiphysics 5.0 by coupling two Multiphysics interface modules namely fluid–structure interaction and piezoelectric physics modules. Using simulation studies, the influence of pump design parameters including diffuser angle, diffuser length, neck width, chamber depth, chamber diameter and diaphragm thickness on net flow rate is studied. An optimal set of design parameters for the proposed micropump is identified. Further, the influence of actuation frequency on the flow rate is analysed. It is found that the proposed micropump is capable to deliver a net flow rate of 20 µl/min and a maximum back pressure attainable is 200 Pa.