A silicon beam-based microcantilever nanoelectrosprayer

Silicon microtechnology is used to fabricate microcantilever based nanoelectrospray emitter chips. The chips are composed of beam-based microcantilevers which form a microfluidic capillary slot terminating in a tip having micrometric dimensions. An original combined microfluidic and micromechanical analysis takes into account microfluidic capillary forces encountered at microsystems dimensions; we propose that such forces can be positively harnessed to effectively reduce tip dimensions to a sub-micron scale. An optimised fabrication process is presented based on silicon-on-insulator technology. The emitter chips were characterised using electrospray ionisation mass spectrometry; we were able to detect the protein lysozyme at a concentration as low as 100 fmol μL−1 (100 nM) and additionally generate peptide mass fingerprints from enzymatic proteolysis of the protein myoglobin. Together these data clearly indicate the usefulness of such electrospray ionisation emitter chips in biomolecular work in general and potentially in the field of proteomics.