An air-chamber-based microfluidic stabilizer for attenuating syringe-pump-induced fluctuations

Syringe pumps are commonly used in microfluidic systems to provide flows with precise control. But small periodic fluctuations on flow induced by the stepper motor in syringe pumps are a problem that influences the characteristics of the microfluidic system. This paper presents a microfluidic stabilizer which contains an air chamber. A specific amount of air is sealed in the air chamber and will attenuate the flow fluctuations by expanding or shrinking its volume. A theoretical model based on Euler equation is developed to clarify the characteristics of the microfluidic stabilizer. The result of simulations by finite element analysis is in good agreement with the theoretical model. A new method based on fluorescence detection and three-dimensional hydrodynamic focusing is developed to measure the flow fluctuations induced by the pumps and also to characterize the buffering capacity of the stabilizer. It is experimentally demonstrated that the fluctuation amplitude is cut to 46% by one microfluidic stabilizer and reduced to 14% by two series connected stabilizers.