We present a design for integrated lab-on-chip microsystems dedicated to mass spectrometry analysis based on the fabrication of watertight microchannels for the circulation of liquids. In this paper, we demonstrate how to fabricate complete polymer microchannels using the negative photoresist SU-8 which has the advantage of being compatible with protein analysis by mass spectrometry. Our method of fabrication requires novel technological steps involving SU-8 multi-layer processing, improved SU-8 adhesion and the use of SU-8 wafer bonding for the watertight closing of the microchannels with a Pyrex wafer. This technique also encompasses the design of various microfluidic elements such as tapered recesses for the housing of capillary tubes allowing the connection of the channels to external systems. Following this, the capillary tubes were used to test the hydrodynamic behaviour of the channels and consequently the efficiency of our technological process in achieving fully watertight structures within our flow rate and pressure specifications.

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We present a novel nanoelectrospray emitter tip based on the principle of a nib rather than a nozzle for nano-electrospray ionization-mass spectrometry (ESI-MS) applications. The fabrication of the micro-nibs relies on micromachining techniques using the epoxy-based negative photoresist SU-8. A double exposure photolithographic process has been employed to form a nib in a membrane-like structure. The nibs contained a capillary slot measuring 20 µm at the tip end. The nib sources were successfully tested on an ion trap mass spectrometer using standard peptide samples at low concentrations, down to 1 µM. High voltage (HV) supply was achieved using platinum wire inserted in a liquid reservoir. A Taylor cone was clearly seen protruding from the nib tip and was determined by the dimensions of the capillary slot.