Microfluidic flow transducer based on the measurement of electrical admittance

A new flow transducer for measuring the flow rate of a conducting fluid in a microchannel is reported. In this paper, the measure of flow of such fluid under laminar flow conditions based on the change of electrical admittance is established with the aid of a pair of electrodes parallel to the line of flow in a glass-PDMS microfluidic device. This flow sensor is simple in design and can be integrated to most of the microfluidic platforms. The effect of flow rate of the electrolyte, the frequency of the applied ac voltage, the voltage applied across the detector electrodes, and the conductivity of the electrolyte are varied to optimize for high sensitivity. The optimized values are then used to demonstrate the measurements of very low flow rates (<1 nL s(-1)). This flow sensor can be extended towards the measurement of chemical and biochemical buffers and reagents.