A method for dynamic system characterization using hydraulic series resistance

Abstract

The pressure required to drive flow through a microfluidic device is an important characteristic of that device. We present a method to measure the flow rate through microfluidic components and systems, including micropumps and microvalves. The measurement platform is composed of two pressure sensors and a glass tube, which provides series resistance. The principle of the measurement is the fluid dynamical equivalent of Ohm's law, which defines the relationship between current, resistance, and voltage that are analogues to flow rate, hydraulic resistance, and pressure drop, respectively. Once the series resistance is known, it is possible to compute the flow rate through a device based on pressure alone. In addition, the dynamic system characteristics of the device—resistance and capacitance—can be computed. The benefits of this method are its simple configuration, capability of measuring flow rate accurately from the more easily measured pressure, and the ability to predict the dynamic response of microfluidic devices.