Integratable Capacitive Sensor for Identification of Microfluidic Two-Phase Flow Patterns in Lab-on-Chip Devices

This paper presents a feasible solution for a real-time sensing of microfluidic two-phase flow in lab-on-chip devices. A capacitive flow pattern sensor has been realized by employing an interdigital electrode configuration and a thin dielectric film. Three main flow patterns were observed in the microchannel, namely, droplet, short slug, and long slug flows. The output signal from the sensor was a real-time capacitance variation induced by the different flow patterns passing the sensing area. Experimental results give an indication of the flow patterns, due to the profile of capacitance variation. Furthermore, the identification of the flow patterns was achieved by autocorrelation of the capacitance variation and evaluation of a constant, specific for a given flow pattern in terms of linear velocity relation. This two-phase flow pattern sensor has potential to be used with other fluids, as long as they are immiscible and have very distinct dielectric properties. [2015-0249]