Precise Manual Assembly of Microfabricated Components

Technology #12069

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Generalized assembly of a planar array of features, e.g., an electrospray thruster array, fabricated according to invention
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Inventors
Professor Akintunde Akinwande
Department of Electrical Engineering and Computer Science, MIT
External Link (www-mtl.mit.edu)
Luis Fernando Velasquez-Garcia
Microsystems Technology Laboratories, MIT
External Link (www-mtl.mit.edu)
Blaise Laurent Patrick
Managed By
Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

Precise hand-assembly of microfabricated components

US Patent 7,900,336
Publications
CNT-Based MEMS/NEMS Gas Ionizers for Portable Mass Spectrometry Applications
Journal of Microelectromechanical Systems,, Vol. 19, No. 3 2010
A Microfabricated Planar Electrospray Array Ionic Liquid Ion Source with Integrated Extractor
Journal of Microelectromechanical Systems,, Vol. 18, No. 3 2009, pp. 679-694
Precision In-Plane Hand Assembly of Bulk-Microfabricated Components for High Voltage MEMS Arrays Applications,
Journal of Microelectromechanical Systems,, Vol. 18, No. 2 2009, pp. 332-326
An Application of 3-D MEMS Packaging: Out-of-Plane Quadrupole Mass Filters
Journal of Microelectromecahnical Systems, Vol. 17, Issue 6 2008
Precision Hand Assembly of MEMS subsystems using DRIE-patterned deflection Spring Structures: An Example of an Out-of-plane Substrate Assembly
Journal of Microelectromecahnical Systems, Vol. 16, No. 3 2007, pp. 598-612
A Micro-Fabricated Linear Array of Electrospray Emitters for Thruster Applications
Journal of Microelectromecahnical Systems, Vol. 15, Issue 5 2006

This novel assembly technique allows for the efficient construction of three-dimensional Micro-Electromechanical  System (MEMS) components, the decoupling of  subsystem process flows, and the integration of subsystems that have characteristic length scales of different orders of magnitude. 

Applications

  • Rod assembly in a linear quadrupole
  • Alignment of extractor and accelerator electrodes in electrospray arrays
  • Precision manual assembly of micro-fabricated components
  • Gridded analyzers, e.g. plasma retarding potential analyzers
  • Field emission electron sources

Problem Addressed

Micro electro-mechanical systems (MEMS) often must be finely tuned to ensure proper device performance. For example, electrodes in electrospray emitter arrays must be tuned to handle high voltages, transmit signals between components of very different length scales, and eliminate misalignment of the electrode-emitter components that introduce irregularities in the emitted stream and reduce device performance. In linear quadrupole mass filters, resolution and ion transmission are greatly affected by the misalignment of the rods and tapers in the device.  In a gridded sensor, e.g. an RPA, the misalignment between the apertures of two adjacent grids decreases the signal that is transmitted, causing a geometric reduction of the signal across the electrode stack. In many cases, the assembly requires active compensation of external effects such as vibration, thermal expansion, etc. to avoid drifts and long-term deterioration of the performance of the device. Also, in certain cases it is highly desirable to decouple the process flows of systems if a technology that allows to precisely putting together the subsystems is utilized; for example, a field emission electron source that uses carbon nanotubes CNTs) would benefit from decoupling the electrode grid to the growth of CNTs from the deposition of dielectric in the electrode edge provided it is possible to to bring together the grid and CNTs with good alignment.

Technology

The inventors describe a technique for the efficient construction of three-dimensional MEMS components, the decoupling of subsystem process flows, and the integration of subsystems with varying characteristic length scales. In this method, components are fortified with features that force proper alignment and cantilever deflection springs that hold the components together once they have been correctly aligned. The technique is applied to the construction of massive electrospray arrays for nanosatellite propulsion and ionization of liquid samples, to the construction of miniaturized linear quadrupoles for portable mass spectrometry, ,to the construction of gridded sensors such as plasma retarding potential analyzers, and to the construction of CNT-based field emission electron sources..

Advantages

  • Allows precision assembly of quadrupole rods, electrodes, and other MEMS components, particularly those that operate at high bias voltages, without using any specialized/precision equipment - to the point to even allowing the assembly of the components by hand
  • Enables precision assembly of reusable MEMS that perform under different conditions of pressure, voltage, and frequency
  • Supports efficient alignment of of arrays of features, e.g. electrode grids to arrays of emitters, electrode grids to arrays of CNTs, or electrode grids part of an electrode stack, and rods in linear quadrupoles