The disclosed invention relates to electrospray and more specifically to wick based electrospray of analytes. The disclosed invention provides a means for improved electrospray extraction of analytes using a capillarity based fluid delivery system. The disclosed invention employs a wire screen mesh sandwiching the substrate media, without impeding capillarity of a wetting solvent spray fluid applied to the substrate. A further benefit is that electrical contact can be made to the substrate. Yet another benefit is that the substrate and wire mesh can be further enclosed in a polymer or other insulating sleeve that is flat and very thin, the preferred form factor is very similar to that of a credit card.