Closed-loop pressure feedback control of a pressure-driven microdroplet generator

To predict the size of droplets formed by pressure-driven flows, the droplet size as a nonlinear function of the pressure ratio is measured experimentally. The mathematical model of the pressure-driven microfluidic device is established, and by varying the volume of a container, comparative and quantitative measurements of the response speed and control accuracy of pressure-driven flows are presented. In particular, a closed-loop control system with feedback of the driven pressure is demonstrated, and the deviation between the measured and the predicted value of the driven pressure can be eliminated by using a PI controller. As a result, by accurately controlling the driven pressure of pressure-driven flows, monodisperse droplets with a desired size can be formed for pressure-driven microdroplet generators.