Method for Flow Measurement in Microfluidic Channels Based on Electrical Impedance Spectroscopy

TL;DR

This paper introduces two innovative microfluidic flow sensors that utilize electrical impedance spectroscopy to measure flow rates, offering simple fabrication, compact design, and easy integration into microfluidic systems.

Contribution

The paper presents novel micro flow sensors based on impedance measurements at metal-liquid interfaces, with detailed analysis and design guidelines for high sensitivity and low noise performance.

Findings

Impedance of metal-liquid junctions varies with flow rate.

Sensors demonstrate high sensitivity and low noise.

Design guidelines enable optimized sensor performance.

Abstract

We have developed and characterized two novel micro flow sensors based on measuring the electrical impedance of the interface between the flowing liquid and metallic electrodes embedded on the channel walls. These flow sensors are very simple to fabricate and use, are extremely compact and can easily be integrated into most microfluidic systems. One of these devices is a micropore with two tantalum/platinum electrodes on its edges; the other is a micro channel with two tantalum /platinum electrodes placed perpendicular to the channel on its walls. In both sensors the flow rate is measured via the electrical impedance between the two metallic electrodes, which is the impedance of two metal-liquid junctions in series. The dependency of the metal-liquid junction impedance on the flow rate of the liquid has been studied. The effects of different parameters on the sensor's outputs and its noise behavior are investigated. Design guidelines are extracted and applied to achieve highly sensitive micro flow sensors with low noise.