Abstract: The invention relates to a micro-nozzle array comprising a plurality of capillaries comprising a first silica-based material and a second silica-based material substantially surrounding the first silica-based material of the plurality of capillaries, and a plurality of nozzles extending beyond a face of the micro-nozzle array, each nozzle corresponding to a single capillary, wherein each nozzle comprises the first silica-based material. The micro-nozzle array may be used in hydrodynamic or electro-osmotic applications. In one embodiment the micro-nozzle array is a multiple electrospray emitter. The invention also relates to methods for preparing and using micro-nozzle arrays.