In-Channel Constriction Valve for Cerebrospinal Fluid Sampling

This paper describes a new multiphase modeling for oil bubble actuation in microchannel with cerebrospinal fluid (CSF). The sampling method is based on an oil droplet microvalve to measure the conductivity and impedance of the CSF in a non-moving liquid. The proposed system was simulated using the finite element software Comsol Multiphysics. For the fluidic modeling and simulation, the multiphase flow level set package of Comsol was used to describe the interaction between oil and CSF. Regarding the electric force computation, the Maxwell stress tensor was explicitly computed in Comsol and then coupled to the fluid dynamics. The values of permittivity of oil (ε_oil) and CSF (ε_CSF) were used, respectively, 2.2 and 109. Simulation results show the actuation of an oil droplet inside a constriction valve, demonstrating the operation of the sampling system.