Apparatus for electrospray emission

An electrospray apparatus comprising:

• a substrate defining a channel;
• a plurality of chevron shaped emitters, each emitter of the plurality defining an indentation in fluid communication with the channel, wherein a working material within the indentation is exposed to an external environment proximal the emitter, wherein a height of an emitter of the plurality of emitters is between 50 and 200 pm, and wherein the chevron shape is an open chevron shape and the emitters protrudes directly from the substrate.