Real-Time Detection of Droplet Velocity Using Open-Source Computer Vision on EWOD Device

Abstract

Electrowetting on dielectric (EWOD) evolved as a new promising fluid handling technology in digital microfluidics (DMF) field. It involves the generation and manipulation of droplet volumes inside microdevices. The monitoring of droplet velocity and its dependence on the applied voltage is an important parameter in this study. In this paper, open EWOD-based device is presented. The array of square electrodes with different electrode size is realized. Biocompatible polydimethylsiloxane (PDMS) is used both as dielectric and a hydrophobic material. The device is tested by using homemade developed droplet controlling system. The droplet motion is successfully performed on a device. The real-time velocity of the droplet as a function of applied voltages and different electrode sizes is obtained. The droplet velocity calculation is done by simple and precise image acquisition-based technique using open-source computer vision (OpenCV) tool. The speed of droplet for 2 × 2 mm square electrode at 350 VDC with 80 µm electrode gap is 9.75 mm/s.