The development of MEMS mass spectrometers

Lab-on-a-chip devices have had a major impact on analytical chemistry. Integration allowed manipulation of minute quantities of reagent, reduced dead volumes and minimised peak broadening. Integrated electrospray nozzles allowed analysis immediately after separation. By comparison, the effort devoted to mass spectrometers has been small. Although attempts were made to miniaturise most common filters, fabrication involves the formation of complex electrodes that generate precise electric fields. Consequently, mass resolution has been poor. High voltages also limited mass range, while poor sample introduction limited sensitivity. Consequently, little progress was made until recently in miniaturizing the electrospray mass spectrometer. These difficulties have been overcome. Greatly improved filters have been developed, vacuum interfaces have been constructed and bench-top ESI-MS is commercially available. This paper summarizes recent developments.