Flow Control Based on Constant Pressure Microfluidic Pump System

摘要

Microfluidic driving and controlling techniques are fundamental and important in microfluidic applications. Traditional reagent driving systems of microfluidic chips such as syringe pump and piezoelectric actuator have their inherent shortcomings. Syringe pumpis easy to deformation and screw motion is unstable mayaffect flow rate. Whilethe flow range of piezoelectric actuator is too narrow. To solve these problems we establisheda constant pressure pump by maintaining stable pressure in a cylinder through the switch of electromagnetic valves, and then liquidin the pressurized reservoiris driven out. A simple PID algorithm is utilized to balance cylinder pressure, while flow rate is measured by a flow sensor. This setup contains a wireless module that can communicate with a PC through Wi-Fi. We use 50μm inner diameter flow resistors with different lengths to verify the relationship among flow rate, flow resistor length and pressure drop. The pump could generate a constant pressure in cylinder and the fluctuation of liquid flow is small. This system can be used as injection system of microfluidic chips and it can also be applied to other biochemical reaction. Operation is easy and users can control the system at a distance.