A New Online Monitoring Method for Water-in-Oil Droplet Based Microfluidic Devices

The online water-in-oil (w/o) droplet monitoring is essential for the uniformity of based microfluidic devices. In this work, a contactless impedance detection (CID) method w/o in devices proposed. proposed method, new CID sensor, which can work at low working frequency and overcome unfavorable influence coupling capacitance, developed to obtain information droplet. Based on obtained information, measurement models are established realize drop length dispersed phase holdup. Then coefficients variation (CVs) two measured parameters calculated evaluate droplets monitoring. Online experiments were carried out device with 500 $\mu \text{m}\,\,\times $ \text{m}$ microchannel. experimental results verify effectiveness method. sensor lower than 50kHz. holdup useful droplets. With models, maximum relative error less 10% range 1.5mm-3.5mm. And 5% 0.20-0.67.