Differentially polarized interface (DPI) digital microfluidics (DMF) platform for biomedical applications
Razu, Md Enayet
Direct Current (DC)-Digital microfluidics (DMF) enables the manipulation of droplets to revolutionize medical diagnostics, environmental assays, and fundamental biology. However, DC-DMF requires high voltages to generate droplet motion, which often breaks dielectric layers at the micro/nano scale, causing electrolysis. To minimize these issues, oil-fillers are commonly used to decrease a voltage requirement by reducing surface tension of the droplet to the surrounding fluid. However, these oil-fillers increase DC-DMF complexity and decreases versatility. In this study, by adapting a differentially polarized interface (DPI) to generate an effective electromechanical force, the voltage required to manipulate a droplet was reduced from 600 V to 85 V without oil-filler or special dielectric materials. By analyzing the temporal profiles of the contact angles during droplet motion under this DPI condition, this study, for the first time, distinguished the contributions of electrowetting and electromechanical forces to the translational movement of droplets. Characterizing the critical change in mass of a single healthy cell as compared to its unhealthy counterpart is of great interest for unraveling the causal mechanism of diseases. In this work, inspired by the pump less transport and controllability of discretized nano-pico liter droplet by digital microfluidics (DMF), the feasibility investigation of cell mass measurement in DMF is performed. Unlike conventional DMF using DC or AC, the developed method by using DMF increases the functionality of DMF by eliminating the need for oil (required by DC), high voltage, and frequency tuning (required by AC), which facilitates high throughput cell mass measurement with maintaining critical cell environment.