https://www.youtube.com/watch?v=qHrBhgwq__Q&feature=player_detailpage Don Pettit, unfortunately, narrates, but doesn't explain much. The main needle is Teflon and the other needle by the injection of the water droplets (seen near the end of the vid) is Nylon. The site asks about the choice of materials. It seems the Nylon needle imparts a charge to the droplets. Is that possible without touching the droplets?