An electrospray emitter (10) for emitting a liquid comprising a sheet (40) having a channel (65) opening to an aperture (55) on a flat emitter surface extending across the sheet (40). A charging electrode (80) coupleable to an electrical supply and arranged to apply an electrical charge to liquid passing into the channel (65). A control electrode (50) proximal to the channel (65) for controlling electrospray emission, that may be embedded in the sheet. A non-wetting or insulating layer (30) may be applied to the sheet.