<p>A droplet actuator comprising: (a) one or more substrates arranged to form a droplet operations gap, the droplet operations gap comprising a region of gap height transition in which the gap height of the droplet operations gap transitions from a first gap height to a second gap height; (b) electrodes associated with the one or more substrates arranged for conducting droplet operations, the electrodes comprising a transition electrode which traverses the region of gap height transition. I At14d 15 2 130 ~' Jj 136 -------- 32a215 a. . 122t~122b 12-1</p>
