Direct Handwriting Manipulation of Droplets by Self-Aligned Mirror-Ewod Across a Dielectric Sheet

In this paper, we demonstrate a novel approach to generate electrowetting on a dielectric sheet over a liquid electrode. A 12.5 μm-thick PVDC film (Saran wrap) was used as the dielectric sheet. Two important phenomena were found: (1) EWOD not only occurs on the manipulated droplet, but also the liquid electrode (mirror-EWOD), (2) the mirror-EWOD causes the manipulated droplet and the liquid electrode self-aligned when they are in comparable sizes. Based on these discoveries, a direct handwriting droplet manipulation platform was designed and fabricated, in which droplets can be transported by a droplet-tipped stylus across a dielectric sheet. PVDC film was also applied in conventional EWOD devices as a disposable dielectric layer.