Optically clear biomicroviscometer with modular geometry using disposable PDMS chips

Abstract

ii AbstractWe have designed and fabricated a biomicroviscometer platform for measurement of microflows of biological fluids. The biomicroviscometer combines an optically clear biocompatible polydimethylsiloxane (PDMS) channel with on-chip integrated microfluidic differential pressure sensors and capabilities of modular channel geometries. This setup allows for a direct measurement of the change in pressure and flow rate, increasing the overall accuracy of the measurement of viscosity and optical observation. We present an introduction of this combined method of measurement with different channel dimensions, using Newtonian and non-Newtonian fluids, and the corresponding calculations. This measurement technique has potential applications in measuring rheological properties at the micro level to further blood disease analysis, and lab-on-a-chip fabrication and analysis.Acknowledgements iii

Comparison of PDMS and NOA Microfluidic Chips: Deformation, Roughness, Hydrophilicity and Flow Performance

“…The geometries of the microfluidic chips used were previously designed in Niko Lee-Yow's study and consist of two tapered chambers connected with parallel channels (Figure 1) [22]. The chip has an inlet path and two outlet paths.…”

“…where ∆P is the difference of pressure, R hyd is the hydrodynamic resistance of the microfluidic device and Q is the flow. The theoretical hydrodynamic resistance of the devices is computed by summing the individual resistances in series or parallel as with electrical circuits using the following equations [22]:…”

“…The hydrodynamic resistance of the rectangular cross-section channels can be calculated using the Hagen-Poiseuille equation as follows [22]: R = 12 µL…”

“…where h is the height of the channel, w is the width of the channel, µ is the viscosity of the fluid, and L is the length of the channel in question. The hydrodynamic resistance of the tapered channels can be calculated using the Darcy law, as follows [22]:…”