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Accelerometers tutorial

Modules

1. Introduction to Acceleration Measurement
2. Piezoresistive Accelerometers
3. Capacitive Accelerometer

pages: 1 2 3 4 5 6 7 | next

 Bulk micromachined capacitive accelerometers

  • Bulk anisotropic etching of silicon is a well-developed technology

  • Comparing to pressure sensors, accelerometers require more sophisticated anisotropic etching (double-sided etching)

  • Size of bulk micromachined accelerometers is typically a few millimetres

 

Surface micromachined capacitive accelerometers

  • Proof mass and its suspensions are fabricated by techniques using LPCVD or electroplating

  • Sacrificial spacing layer is removed after the structural film is deposited to release the structure from the substrate

  • Sensors are typically few hundreds of micrometers on each side, with the thickness of each layers determined
    by the deposition times of those layers

  • Performance of these devices depends critically on

    • Uniformity and mechanical properties of the deposited layers

    • Effects of residual stress in the films

  • Interface electronics are often integrated on the same chip because the sensing element is small and on only one side
    of the wafer

  • Different variations of the basic capacitive principles employ lateral, transversal, or torsional movement
    of either one movable electrode or of a set of interdigitated electrodes.

1. Introduction to Acceleration Measurement
2. Piezoresistive Accelerometers
3. Capacitive Accelerometer

pages: 1 2 3 4 5 6 7 | next

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