Intelligent droplet manipulation in electrowetting devices via capacitance-based sensing and actuation for self-adaptive digital microfluidics

In this work, we report on an integrated digital microfluidic system for precise sensing and automatic actuating droplets (ISPSAA) based on electrowetting on dielectric (EWOD). A feedback controller in the system is capable of locating, judging and controlling individual droplet independent of liquid composition. An integrated position sensor is capable of tracking the continuous displacement of a droplet between electrodes through the feedback of capacitance difference in real time, and thus improves the droplet control precision. Real-time droplet allocation and actuation have been achieved in a digital and precise way by combining the droplet sensing and driving functions. A defect electrode on the droplet transportation path can also be sensed and avoided in an intelligent way by adjusting corresponding electrodes and parameters to actuate the droplet to reach destination position based on the designed route with minimum number of actuated electrodes. Because of its portability, low cost, and adaptive functions, ISPSAA are helpful for further understanding and implementation of digital microfluidic systems for practical applications.