Producing and Measuring Oscillatory Shear in a Novel Microfluidic Chip

Purpose: To demonstrate the effectiveness of a novel microfluidic device mimicking oscillatory blood flow, allowing cell biologists to examine how endothelial cells respond to a range of oscillatory shear stress levels. Methods: The microfluidic chip consists of a circular-shaped reservoir, leading to a rectangular channel that is examined under a microscope. The plunger is connected to a speaker system and oscilloscope, allowing the plunger to apply a range of frequencies (5-60Hz) and voltages (5-10 V, leading to a variety in oscillation amplitudes) to the reservoir region. 1.1 um fluorescent particles diluted in distilled water were used for tracking. Processing was done through particle image velocimetry (PIV) which uses a cross-correlation algorithm. We used matlab to plot average velocity profiles for a cycle, and extracted data points along the centre of the velocity profiles corresponding to the maximum velocities. Results: The oscillatory chip demonstrated the ability to effectively and accurately deliver oscillatory flow between 10-60Hz using 5-10V, resulting in a variety of oscillation frequencies and amplitudes. Plotting velocity maximum values vs. voltage for frequencies 10-60 Hz demonstrated a linear trend. 3D oscillatory-flow paraboloids can be used in calculating maximum shear stress values for oscillatory flow. Conclusions: Our analysis demonstrates that this microfluidic chip is able to execute controlled shear stress conditions to test how endothelial cells respond to oscillatory shear