Design, fabrication and test of a microfluidic nebulizer chip for desorption electrospray ionization mass spectrometry.

This paper presents design, microfabrication, and test of a microfluidic nebulizer chip for desorption electrospray ionization mass spectrometry (DESI-MS) in proteomic analysis. The microfluidic chip is fabricated using cyclic olefin copolymer (COC) substrates. The fluidic channels are thermally embossed onto a base substrate using a nickel master and then a top substrate is thermally bonded to seal the channels. Carbon ink embossed into the top COC substrate is used to established electrical connection between the external power supply and the liquid in the channel. The microfluidic chip to external capillary connection is fabricated using Nanoport() interconnection system. Preliminary leakage test was performed to demonstrate the interconnection system is leak-free and pressure test was performed to evaluate the burst pressure. Finally, the nebulizer chip was used to perform DESI-MS for analyzing peptides (BSA and bradykinin) and reserpine on the nanoporous alumina surface. DESI-MS performance of the microfluidic nebulizer chip is compared with that obtained using a conventional DESI nebulizer.