Electrowetting measurements were performed using an Autolab PGSTAT302N potentiostat (Metrohm) operated via Nova 1.11.2 software. The experimental procedure followed for monitoring the contact angle dependence on the applied bias was comprised of consecutive potential pulses from 0 V to either -1.5 V or +1.3 V with a step of 50 mV. The duration of the pulses was adjusted to 10 s.