A dual-axis MEMS capacitive inertial sensor with high-density proof mass

This paper introduces a prototype of the inertial sensor based on electromagnetic suspension. By analyzing and simulating the change of the magnetic field, the dynamic equation of proof mass has been deduced. The device has the characteristics of a high-frequency accelerometer and a vibration frequency sensor, and the horizontal and vertical frequency ranges of the magnetic suspension acceleration measurement system are 50–500 Hz and 35–650 Hz, and the acceleration measurement ranges are ±3.3 m/s 2 and ±10 m/s 2 , respectively. Compared with the MPU6050 accelerometer, this measurement method has higher sensitivity and retains more vibration acceleration information of the measured object. This paper provides a new idea for the design of the acceleration sensor.

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A Micromachined Earth Sensor Based on Measuring the Gravity Gradient Torque

Volume 12: Micro and Nano Systems, Parts A and B ◽

10.1115/imece2009-12762 ◽

2009 ◽

Author(s):

K. Ghose ◽

H. R. Shea

Keyword(s):

Proof Mass ◽

Inertial Sensor ◽

Low Earth Orbit ◽

Relative Orientation ◽

Gravity Gradient ◽

Earth Orbit ◽

Optical Access ◽

The Earth ◽

Ir Emission

We present the fabrication and testing of a novel MEMS inertial sensor that directly measures the gravity gradient in low Earth orbit in order to sense the relative orientation of a satellite with respect to the Earth. Instead of the current Earth sensing methods that determine the Earth vector by sensing the Earth’s IR emission, we present a much lighter and more compact MEMS-based approach that determine the Earth vector by measuring the Gravity Gradient Torque on an elongated silicon proof mass. Current Earth sensors require optical access on multiple faces of the satellite. This MEMS-based approach does not require optical access.

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Design and Simulation of MEMS Based Tuning Fork Micro-Gyroscope

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.110-116.5036 ◽

2011 ◽

Vol 110-116 ◽

pp. 5036-5043

Author(s):

Suthin Khankhua ◽

Muhammad Waseem Ashraf ◽

Nitin Afzulpurkar ◽

Shahzadi Tayyaba ◽

Chumnarn Punyasai

Keyword(s):

Vibration Amplitude ◽

Tuning Fork ◽

Proof Mass ◽

Inertial Sensor ◽

Sense Mode ◽

Small Vibration ◽

Common Mode ◽

Microelectromechanical System ◽

Proposed Model ◽

Simulation Results

In this paper, design, analysis and simulation of microelectromechanical system (MEMS) based inertial sensor type of tuning fork micro gyroscope have been presented. CoventorWare has been used for design and simulation. The proposed design has improved the performances and structure for small vibration amplitude to minimize the mechanical crosstalk. Simulation results show that the capacitance in sense mode, which is detected by variable-gap capacitors, is equal to 2.68 pF in each side of sense mode. Oscillations in drive and sense electrodes with 1-DOF and proof mass with 2-DOF ensure that the proposed model has no common mode that causes mechanical crosstalk.

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Planar defects in ordered (Ga,In)P

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106570 ◽

1988 ◽

Vol 46 ◽

pp. 902-903

Author(s):

S. McKernan ◽

C. B. Carter ◽

D. Bour ◽

J. R. Shealy

Keyword(s):

Electron Diffraction ◽

Vapor Phase ◽

Growth Direction ◽

High Density ◽

Ordered Structure ◽

Planar Defects ◽

Diffraction Patterns ◽

Ternary Semiconductors ◽

Anion Species ◽

Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

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Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138932 ◽

1995 ◽

Vol 53 ◽

pp. 512-513

Author(s):

L. Mulestagno ◽

J.C. Holzer ◽

P. Fraundorf

Keyword(s):

Sample Preparation ◽

Milling Time ◽

High Density ◽

Low Density ◽

Ion Milling ◽

High Quality ◽

Variable Angle ◽

Major Disadvantage ◽

Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

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Using the scanning electron microscope for failure analysis of high density magnetic media

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126755 ◽

1987 ◽

Vol 45 ◽

pp. 392-393

Author(s):

Evelyn R. Ackerman ◽

Gary D. Burnett

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Failure Analysis ◽

High Density ◽

Magnetic Media ◽

Specific Data ◽

Retrieval Systems ◽

Operating Environments ◽

The Media ◽

Scanning Electron

Advancements in state of the art high density Head/Disk retrieval systems has increased the demand for sophisticated failure analysis methods. From 1968 to 1974 the emphasis was on the number of tracks per inch. (TPI) ranging from 100 to 400 as summarized in Table 1. This emphasis shifted with the increase in densities to include the number of bits per inch (BPI). A bit is formed by magnetizing the Fe203 particles of the media in one direction and allowing magnetic heads to recognize specific data patterns. From 1977 to 1986 the tracks per inch increased from 470 to 1400 corresponding to an increase from 6300 to 10,800 bits per inch respectively. Due to the reduction in the bit and track sizes, build and operating environments of systems have become critical factors in media reliability.Using the Ferrofluid pattern developing technique, the scanning electron microscope can be a valuable diagnostic tool in the examination of failure sites on disks.

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