On effect of viscoelastic characteristics of polymers on performance of micropump

Abstract

Micropumps are the most important components of lab-on-a-chip devices, which are becoming popular recently due to their enormous advantages. Among the different designs of micropumps, the nozzle–diffuser valveless design is the most preferred one due to simplicity in manufacturing. For the simulation of these pumps, the local fluid–structure interaction modeling is important to get the performance accuracy. To capture fluid–structure interaction accurately, an appropriate selection of the fluid as well as the structural modeling approaches are very essential. It is well known that the polydimethylsiloxane materials behave as a viscoelastic material. However, most of the earlier studies on polydimethylsiloxane micropump modeling have considered polydimethylsiloxane as a linear elastic material. In this article, a nozzle–diffuser-based valveless micropump is modeled using a fluid–structure interaction approach along with a linear viscoelastic model for polydimethylsiloxane. The mechanical properties of the polydimethylsiloxane material are experimentally obtained using dynamic mechanical analysis for the range of micropump operating frequencies. These viscoelastic properties of polydimethylsiloxane, with varying proportionate of curing agent, are introduced in the fluid–structure interaction model of micropump using the Kelvin–Voigt model. The results are presented in the form of micropump performance parameters such as diaphragm deflection, von-Mises stresses, swept volume, and fluid flow rate.