Abstract
This paper presents a novel capacitive microelectromechanical systems (MEMS) accelerometer with slanted supporting beams and all-silicon sandwich structure. Its sensing mechanism is quite similar to an ordinary sandwich-type MEMS accelerometer, except that its proof mass is suspended by a beam parallel to the {111} plane of a (100) silicon wafer. In this way, each sensing element can detect accelerations in two orthogonal directions. Four of these sensing elements could work together and constitute a 3-axis micro-accelerometer by using a simple planar assembly process. This design avoids the traditional 3-axis accelerometer’ disadvantage of possible placement inaccuracy when assembling on three different planes and largely reduces the package volume. The slanted-beam accelerometer’s performance was modeled and analyzed by using both analytical calculations and finite element method (FEM) simulations. A prototype of one sensing element was fabricated and tested. Measured results show that this accelerometer has a good bias stability 76.8 ppm (1σ, tested immediately after power on), two directional sensitivities (sensitivity angle α = 45.4°) and low nonlinearity (<0.5%) over a sensing range up to ±50 g, which demonstrates a great opportunity for future high-precision three-axis inertial measurement.
Highlights
Microelectromechanical systems (MEMS) accelerometers are used in a wide range of markets and applications and can be classified in several categories: consumer grade, tactical grade and navigation grade depending on their performances, reliability and cost [1,2]
A preliminary test was performed to validate the effectiveness of a fabricated slanted-beam accelerometer
Its output signal was recorded immediately after the power was turned on, and the result in Figure 7a shows that this accelerometer has demonstrated a short-time bias stability of
Summary
Microelectromechanical systems (MEMS) accelerometers are used in a wide range of markets and applications and can be classified in several categories: consumer grade, tactical grade and navigation grade depending on their performances, reliability and cost (see Table 1) [1,2]. Inertial Measurement Units) on the market are orthogonally assembled by three individual and identical single-axis accelerometers on three different planes [12,13] These MIMUs are suffering from the disadvantages of bulky package volume and possible assembly misalignment. The combination of two different sensing structures allows a full optimization of each sensing structure’s performance, but it will result in a much more complex fabrication process Another possible solution using slanted-beam sensing structures was investigated in this paper, which employs very simple bulk silicon micromachining technologies and can realize three-axis acceleration detection by fabricating four similar sensing elements on a single die. The fabricated prototype exhibits a good bias stability and low nonlinearity, experimentally demonstrating the effectiveness of our proposed design and fabrication technology
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