A microengineered alignment bench for a nanospray ionization source

A microengineered alignment bench for a nanospray ionization system is described. The bench combines a V-groove mount for a capillary-based nano-ESI source with an extraction electrode and allows accurate axial and transverse alignment of the capillary. An input channel and plenum for nebulizer gas are also demonstrated. The structure is formed in two halves, which are assembled by stacking. Electrically conducting features are constructed by crystal plane etching, deep reactive ion etching and metallization of silicon, while the insulating base is formed in a photopatterned plastic. Low voltage (about 850 V) positive ion emission is demonstrated using commercial nanospray (15 μm ID) capillaries, with total ion currents >10 nA. The structures are robust, and can survive voltages >1 kV and immersion in common solvents. Mass spectrometry is carried out using a commercial atmospheric pressure ionization instrument, and high signal stability is demonstrated.