The invention provides related apparatus and methods of making an
integrated electrospray tip by depositing ionic and/or electronic
conductor materials onto a planar substrate. The invention also features
methods of forming an electrospray apparatus comprising coupling a first
planar substrate to the surface of a second planar substrate, wherein a
surface on at least one of the substrates includes one or more
microfluidic channels and/or reservoirs which are at least partially or
totally enclosed therebetween. The conductive regions of the apparatus do
not intersect the microfluidic channels within other portions of the
apparatus provided preferably. The invention further provides related
apparatus and methods for manufacturing and using microfluidic devices
with integrated electrodes for electrospray ionization. The electrospray
apparatus in some embodiments may include an electronic conductor
electrode or an ionic conductor electrode formed from a microfluidic
channel containing a conductive material selected from a variety of
solutions and gels.