Micromachined low frequency rocking accelerometer with capacitive pickoff

Patent · Mon Jan 01 00:00:00 EST 2001

OSTI ID:873725

Lee, Abraham P ^[1]; Simon, Jonathon N ^[2]; McConaghy, Charles F ^[3]

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1. Arlington, VA
2. San Leandro, CA
3. Livermore, CA

A micro electro mechanical sensor that uses capacitive readout electronics. The sensor involves a micromachined low frequency rocking accelerometer with capacitive pickoff fabricated by deep reactive ion etching. The accelerometer includes a central silicon proof mass, is suspended by a thin polysilicon tether, and has a moving electrode (capacitor plate or interdigitated fingers) located at each end the proof mass. During movement (acceleration), the tethered mass moves relative to the surrounding packaging, for example, and this defection is measured capacitively by a plate capacitor or interdigitated finger capacitor, having the cooperating fixed electrode (capacitor plate or interdigitated fingers) positioned on the packaging, for example. The micromachined rocking accelerometer has a low frequency (<500 Hz), high sensitivity (.mu.G), with minimal power usage. The capacitors are connected to a power supply (battery) and to sensor interface electronics, which may include an analog to digital (A/D) converter, logic, RF communication link, antenna, etc. The sensor (accelerometer) may be, for example, packaged along with the interface electronics and a communication system in a 2".times.2".times.2" cube. The proof mass may be asymmetric or symmetric. Additional actuating capacitive plates may be used for feedback control which gives a greater dynamic range.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 6230566
• OSTI ID: 873725
• Country of Publication: United States
• Language: English

Related Subjects

micromachined
frequency
rocking
accelerometer
capacitive
pickoff
micro
electro
mechanical
sensor
readout
electronics
involves
fabricated
deep
reactive
etching
central
silicon
proof
mass
suspended
polysilicon
tether
moving
electrode
capacitor
plate
interdigitated
fingers
located
movement
acceleration
tethered
moves
relative
surrounding
packaging
example
defection
measured
capacitively
finger
cooperating
fixed
positioned
500
hz
sensitivity
minimal
power
usage
capacitors
connected
supply
battery
interface
analog
digital
converter
logic
rf
communication
link
antenna
etc
packaged
times
cube
asymmetric
symmetric
additional
actuating
plates
feedback
control
dynamic
range
dynamic range
power supply
feedback control
rocking accelerometer
capacitive pickoff
power usage
minimal power
frequency rocking
mechanical sensor
communication link
capacitive plate
capacitor plate
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