Electrospray Based High Vacuum Diffusion Pump for Mass Spectrometers

Mass spectrometers necessitate a partial pressure zone to allow for the process of mass characterization of the analyte under consideration. The reasons for transforming neutral molecules into charged ions include (1) the ability to control the trajectories and destinations of charged species by appropriate combinations of electric and magnetic fields and (2) detectability that is generally much greater for ions than for neutral molecules because each ion gives rise to at least one electron in a primary signal current that can be greatly amplified by known techniques. The miniaturization of mass spectrometers suitable for handheld form factor has been principally hampered by a lack of new vacuum pump technology. Attempts to miniaturize turbomolecular pumps for portability suffer number of drawbacks in these applications. Chief among these are high cost, limited life, complexity, susceptibility to torque-induced gyroscopic precession, and a potential for catastrophic failure which may subject the user to possible shrapnel. An alternative is proposed whereby electrosprays of nonvolatile fluids may be employed as a new generation of high vacuum diffusion pump. Electrospray pumps do not require the heaters or cooling found in conventional oil based diffusion pumps, offering milliwatt instant-on operation, no moving parts, axis insensitivity, and low cost.