Surface Tension Flows inside Surfactant-Added Poly(dimethylsiloxane) Microstructures with Velocity-Dependent Contact Angles

Micromachines

Jyh Jian Chen²  Shih Chuan Liao²  Mao Hsun Liu³  Jenn Der Lin¹  Tsung Sheng Sheu⁴ 

[1] Department of Power Mechanical Engineering, National Formosa University, 64, Wunhua Road, Huwei, Yunlin 63201, Taiwan; E-Mail:;Department of Biomechatronics Engineering, National Pingtung University of Science and Technology, 1, Shuefu Road, Neipu, Pingtung 91201, Taiwan; E-Mails:;Department of Mechanical Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan; E-Mail:;Department of Mechanical Engineering, Chinese Military Academy, 1, Weiwu Road, Fengshan, Kaohsiung 83059, Taiwan; E-Mail:

关键词: microfluidics;    dynamic contact angle;    gas-liquid interface;    surface tension;    filling process;   

DOI  :  10.3390/mi5020116

来源: mdpi

【 摘 要 】

Filling of liquid samples is realized in a microfluidic device with applications including analytical systems, biomedical devices, and systems for fundamental research. The filling of a disk-shaped polydimethylsiloxane (PDMS) microchamber by liquid is analyzed with reference to microstructures with inlets and outlets. The microstructures are fabricated using a PDMS molding process with an SU-8 mold. During the filling, the motion of the gas-liquid interface is determined by the competition among inertia, adhesion, and surface tension. A single ramp model with velocity-dependent contact angles is implemented for the accurate calculation of surface tension forces in a three-dimensional volume-of-fluid based model. The effects of the parameters of this functional form are investigated. The influences of non-dimensional parameters, such as the Reynolds number and the Weber number, both determined by the inlet velocity, on the flow characteristics are also examined. An oxygen-plasma-treated PDMS substrate is utilized, and the microstructure is modified to be hydrophilic. Flow experiments are conducted into both hydrophilic and hydrophobic PDMS microstructures. Under a hydrophobic wall condition, numerical simulations with imposed boundary conditions of static and dynamic contact angles can successfully predict the moving of the meniscus compared with experimental measurements. However, for a hydrophilic wall, accurate agreement between numerical and experimental results is obvious as the dynamic contact angles were implemented.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.