Microstructured Photonic Fibers as Multichannel Electrospray Emitters

Novel multichannel electrospray emitters are presented that use silica-based microstructured fibers (MSFs) to split the flow allowing efficient desolvation during electrospray. The MSFs investigated in this study possess 30-168 individual fluidic channels (each channel being 5 mu m in diameter) that form a 2D emitting array. Multiple flow paths afford stable electrospray at flow rates ranging from the microspray (e.g., 1000 nL/min) to the nanoelectrospray (e.g., 10 nL/min) regime with moderate to negligible flow-induced backpressures. The electrospray stability of highly aqueous solutions (up to 99.9% water with 0.1% acetic acid) is enhanced through modification of the emitting surface with a hydrophobic silylation reagent (chlorotrimethylsilane). Furthermore, by successfully spraying highly concentrated salt solutions, this study demonstrates that multichannel MSF emitters provide enhanced robustness to clogging, leading to increased operational throughput.