Improvement of rectification effects in diffuser/nozzle structures with viscoelastic fluids

• Main Authors: Nguyen, Nam-Trung, Lam, Yee-Cheong, Ho, Soon-Seng, Low, Cassandra Lee-Ngo
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics
• Online Access: https://hdl.handle.net/10356/100167; http://hdl.handle.net/10220/24103
• Institution: Nanyang Technological University

This paper reports the improvement of rectification effects in diffuser/nozzle structures with viscoelastic fluids. Since rectification in a diffuser/nozzle structure with Newtonian fluids is caused by inertial effects, micropumps based on this concept require a relatively high Reynolds numbers and high pumping frequencies. In applications with relatively low Reynolds numbers, anisotropic behavior can be achieved with viscoelastic effects. In our investigations, a solution of dilute polyethylene oxide was used as the viscoelastic fluid. A microfluidic device was fabricated in silicon using deep reactive ion etching. The microfluidic device consists of access ports for pressure measurement, and a series of ten diffuser/nozzle structures. Measurements were carried out for diffuser/nozzle structures with opening angles ranging from 15° to 60°. Flow visualization,pressure drop and diodicity of de-ionized water and the viscoelastic fluid were compared and discussed. The improvement of diodicity promises a simple pumping concept at low Reynolds numbers for lab-on-a-chip applications.