Nano Science and Technology InstituteNano Science and Technology Institute
Nano Science and Technology Institute 2003 NSTI Nanotechnology Conference & Trade Show
Nanotech 2003
BioNano 2003
Program
Sunday
Monday
Tuesday
Wednesday
Thursday
Index of Authors
2003 Sub Sections
Proceedings
Organization
Press Room
Sponsors
Exhibitors
Venue
Organizations
NSTI Events
Subscribe
Site Map
Nanotech Proceedings
Nanotechnology Proceedings
Supporting Organizations
Supporting Organizations
Event Contact
696 San Ramon Valley Blvd., Ste. 423
Danville, CA 94526
Ph: (925) 353-5004
Fx: (925) 886-8461
E-mail:
 
 

A New Method of Excluding The External Acceleration’s Effect

: J-M. Cho, K. S. Kim, S. D. An, H. J. Park and G. Hahm
Navigation MEMS Lab., Central R&D Center, Samsung Electromechanics Co., LTD., KP

Keywords: magnetometer-accelerometer, silicon micromachining, silicon-on-glass wafer, low vacuum, current flow

Abstract:
A new type of magnetometer-accelerometer is developed with a silicon micromachining. The operation principle of the sensor is based on the well known Lorentz force caused by the interaction of a current and an external magnetic field on a suspended conducting beam. The resonant magnetometers that use the Lorentz force have been reported but they have the critical problem of failing to exclude the effect of acceleration when a magnetic field and acceleration are applied simultaneously. Therefore, we have conceived a new resonant micro sensor detecting both acceleration and the geomagnetic field simultaneously and minimizing the interference with each other. To realize this concept, a conducting line is formed on a spring part of a silicon accelerometer having two mass plates as shown in Fig. 1. The upper sensing electrode detects acceleration in the perpendicular direction and a magnetic field in the parallel direction to the substrate. The vertical displacement of the structure is converted into a capacitance change by the mass and the upper sensing electrode, which form a parallel-plate capacitor. The vibrating mass and springs are fabricated on a silicon-on-glass (SOG) wafer and packaged by a silicon-gold eutectic bonding. Gold is evaporated on the silicon of SOG and acts as a current carrying conductor and a eutectic counterpart. Indeed, the resonant operation in high vacuum condition is successful in increasing the sensitivity. But it causes unwanted problems such as the lack of shock reliability, reproducibility, etc. In order to solve this problem, we have tried it in a very low vacuum (about Q-factors below 10). To operate the sensor, an ac current of its mechanical resonant frequency is driven through the conducting line. The measured current flow and resistance are 10 mA and 10 Ω respectively, so 1 mW is consumed in the current driving element. When 1g (= 9.8 m/s2) of acceleration and 70 mTpp of magnetic field (in South Korea) are applied to the sensor, the measured sensitivity are 300 mV/g for accelerometer and 290,000 V/A·T for magnetometer, respectively. This newly developed sensor can be used in a portable navigator such as SmartPhones and PDAs that need a small, low cost and low power electronic compass.

NSTI Nanotech 2003 Conference Technical Program Abstract

 
Featured Sponsors
Nanotech Sponsors
News Headlines
NSTI Online Community
 
 

© Nano Science and Technology Institute, all rights reserved.
Terms of use | Privacy policy | Contact