Batch Fabricated Rectangular Rod, Planar MEMS Quadrupole with Ion Optics

Technology #12717

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Rod Quadrupole Selector: (a) Cross Section of device across width. (b) Schematic of final device. (c) Cross section along length of device  with ion trajectories shownCompleted Quadrupole Mass Selector: (a) Device size compared to quarter. (b) Scanning electron micrograph of the the cross section along the dashed line in (a)
Professor Akintunde Akinwande
Deparment of Electrical Engineering and Computer Science, MIT
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Luis Fernando Velasquez-Garcia
Microsystems Technology Laboratories, MIT
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Kerry Cheung
Microsystems Technology Laboratories, MIT
Managed By
Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

Batch fabricated rectangular rod, planar MEMS quadrupole with ion optics

US Patent 7,935,924
Performance Characteristics of a MEMS Quadrupole Mass Filter with Square Electrodes - Experimental and Simulated Results
IEEE Trans. on Instrum. and Measurement, Vol. 59, No. 9, 2010, pp. 2458-2467
Chip-Scale Quadrupole Mass Filters for Portable Mass Spectrometry
Journal of Microelectromechanical Systems, Vol. 19, No. 3, 2010, pp 469-483

This  technology presents a method for batch fabricating MEMS quadrupoles to optimize low cost and microscale applications in mass spectrometry and gas chromotagraphy


  • Gas chromatography
  • Mass spectrometry
  • Charged beam manipulation

Problem Addressed

Demand for rugged, small, light, inexpensive, and power efficient gas chromatography and mass spectrometry systems has recently driven the development of miniaturized mass filters. Producing these devices involves combinations of precision machining or micro-fabrication, and downstream manual assembly, all of which are costly. In particular, manual assembly of mass filters is expensive and inefficient, requiring individual tuning of each filter as each filter has unique misalignment conditions.


This technology describes a method for batch fabrication of MEMS quadrupoles, utilizing economy of scale for production and distribution.  The quadrupole mass filters produced by this method have a rectangular electrode cross section. The performance reduction caused by the use of non-circular electrodes is compensated for by operating these devices in high-order stability regions that yield higher resolution. 

The use of batch fabrication techniques allows very precise manufacture of the quadrupoles; because the quadrupoles are batch-fabricated, quadrupoles from the same batch share the same misalignment configuration, which means tuning of the quadrupoles in an analytical system can be more easily performed. The invention includes a series of etch steps, electrical insulator growth/deposition steps, wafer bonding steps, and metal deposition that can be utilized to fabricate the device.


  • Miniaturization of quadrupole mass filters to enable portability and reduce power consumption.
  • Batch fabrication to produce low-cost quadrupoles mass filters in commercial quantities
  • Integrated optics, prefileters, drive signal processing, allow operating devices in high stability regions to meet performance requirements.