Methods and apparatus for droplet deposition

The present invention relates to methods and apparatus for depositing droplets of fluid onto a medium, particularly in the field printing. The apparatus 10 comprises an array of chambers including a first plurality of chambers 12 arranged to selectively deposit droplets of fluid and a second plurality of chambers 13 not configured for selective deposition of droplets of fluid. The plurality of first chambers 12 are arranged in pairs separated from adjacent pairs by at least one chamber 13 of the second plurality of chambers. Each chamber is separated from adjacent chambers by walls 14, the walls 14 being actuable to eject droplets of fluid from the chambers 12. Each active chamber has a first electrode 1a on a surface of the second wall 14-2 internal to the active chamber 12 and a second electrode 1b on an opposed surface of the second wall, external to the active chamber; and a surface of the first wall 14-1 located internally to the active chamber, the surface of the first wall having either no electrode thereon or having a third electrode thereon.