The present study reports an investigation of capillary transport with a suspension of microbeads and biomolecules. Series of experiments are performed to deduce the concentration based surface tension and contact angle expression for microbead and biomolecule suspension. It is observed that, the microbead suspension restricts the spreading of the fluid front. Hence a decrease in the surface tension and an increase in the contact angle is observed as the concentration of suspension is increased. Different expressions for contact angle and surface tension depending on the range of the microbead concentrations are deduced. Theoretical model to predict the capillary transport in rectangular microchannel considering the change in physical and surface properties of the fluid is developed. The capillary transport in a microfabricated silicon microchannel is observed for fluid with and without microbead. Theoretical and experimental observations match quite well, whereas the quantitative difference in case of transport with microbead suspension is observed. Thus, the effect of suspension on the fluid properties can not be neglected in a capillary transport.

Date Published: 17 February 2010
PDF: 9 pages
Proc. SPIE 7593, Microfluidics, BioMEMS, and Medical Microsystems VIII, 75930O (17 February 2010); doi: 10.1117/12.842215

Published in SPIE Proceedings Vol. 7593:
Microfluidics, BioMEMS, and Medical Microsystems VIII
Holger Becker; Wanjun Wang, Editor(s)