Numerical modeling and experimental validation of uniform microchamber filling in centrifugal microfluidics

Abstract

In this paper, a comprehensive approach to numerical and experimental analysis of microchamber filling in centrifugal microfluidics is presented. In the development of micro total analysis systems, it is often necessary to achieve complete, uniform filling of relatively large microchambers, such as those needed for nucleic acid amplification or detection. With centrifugal devices, these large microchambers must often be orientated perpendicularly to the direction of centrifugal force and are usually bounded by materials with varying surface properties. The resulting fluidic flow in such systems can be complex and is not well characterized. To gain further insight into complex fluidic behavior on centrifugal microfluidic platforms, numerical modeling using the Volume of Fluids method is performed to simulate microchamber filling in a centrifugal microfluidic device with integrated sample preparation, amplification, and detection capabilities. Parametric analyses are performed using numerical models to predict microchamber filling behavior for a range of pressure conditions. High-speed flow visualization techniques are used to track the liquid meniscus during filling of the microchambers, and comparison to the numerical predictions for experimental validation is achieved by analyzing the liquid volume fraction as a function of the non-dimensional temporal profile during filling. When channel filling profiles are compared, the numerical model predictions utilizing static conditions are in strong agreement with the experimental data. When dynamic modeling conditions are used, the numerical predictions are extremely accurate as compared to the experimental data.

Whole Blood Immunoassay Based on Centrifugal Bead Sedimentation

“…Extensive development efforts have yielded multiple types of immunoassay applications, including simple modifications of data compact discs, sophisticated assay platforms, and printed protein arrays (4 -11 ). In addition, there has been substantial progress toward centrifugal systems with self-contained sample processing capabilities for detection of both DNA/RNA and protein (12)(13)(14)(15)(16)(17). In a notable recent example, researchers at the Samsung Advanced Institute of Technology developed a fully integrated, portable immunoassay platform capable of directly processing whole blood (11 )…”

System-level simulation of liquid filling in microfluidic chips

“…As a commercial software package, the VOF module in CFD-ACE+ has been widely validated for liquid filling and droplet evolution in microchannels and chambers by experimental results from various sources. [18][19][20][21][22][23] The parameters used in the simulation include the density of the liquid, = 1000 kg/ m 3 , the surface tension coefficient, = 0.0725 N / m, and the dynamic viscosity of the liquid, = 8.9ϫ 10 −4 m 2 / s. An automatic adaptive time step approach is used in CFD-ACE+ simulation and a constant small time step size of 0.0005 s is used in the system-level model to ensure high accuracy for all case studies in the paper. The average grid densities in CFD-ACE+ simulation are 20 nodes/mm in the longitudinal direction of the microchannel and 100 nodes/mm in the transverse direction.…”

Experimental validation of numerical study on thermoelectric-based heating in an integrated centrifugal microfluidic platform for polymerase chain reaction amplification

“…25 In this study, when the thermocycling experiments are performed on the centrifugal microfluidics platform, the temperature gradient due to heat conduction is expected to be higher along the thickness of the centrifugal disc (CD), especially because of the small size of the PCR microchamber. Numerical analysis was performed for predicting the transient thermal response of the PCR microchamber in order to explore the effect of the various design parameters (e.g., microchamber dimensions, material properties, power input, or heater layout).…”