Precision Engineering Research Group Massachusetts Institute of Technology An Instrument to Measure the Force- Displacement Characteristics of MEMS Mechanisms Supervisors: Alexander H. Slocum, Jeffrey H. Lang Jin Qiu, Joachim Sihler, Jian Li
Jan 04, 2016
Precision Engineering Research Group
Massachusetts Institute of Technology
An Instrument to Measure the Force-Displacement Characteristics of MEMS Mechanisms
Supervisors: Alexander H. Slocum, Jeffrey H. Lang
Jin Qiu, Joachim Sihler, Jian Li
In itia l shape as etchedw ith no in ternal stress.
Second stable positionafter snap through
in itia l apex height d0
Actuation forcecauses deflection
Snap through
current
Bistable Relay Principle Precision Engineering Research Group
Front side Back side
Precision Engineering Research Group
Fabrication Imperfectness
Unpredictable tapering of the DRIE process requires post manufacture minitoring to verify mechanical properties
Prototype Close-ups Precision Engineering Research Group
Data acquisition unit with reference flexure, amplification lever, and displacement sensos
Needle used for mechanical contact
FMEMS
F()
F
Fundamental Goal:Measure the stiffness of a MEMS flexure
MEMS flexure
0 1 2 3 4 5 6 7 8 9
0 1 2 3 4 5 6 7 8 9
9 8 7 6 5 4 3 2 1 0
9 8 7 6 5 4 3 2 1 0
reference flexure
FMEMS
d d1
MEMS flexure
=d2-d1
FMEMS=kref * d2
kMEMS=FMEMS /
MEMS flexure reference flexure
Fundamental F-D curve principle Precision Engineering Research Group
Functionality of the Amplification Lever Design Precision Engineering
Research Group
d 2
a
d1
b
l
M EM S flexurereference flexure
b
t
F M dM
d2+d2 d 1+d1
d2d1
HP Barcode Readers as Displacement Sensor
10 nm resolution
bar codereader 1
bar codereader 2
d1 d2
d
m irror1
m irror2
d=d1-d2
d
i
4.5 m m3 m m 6 m m
linearrange
0.5 m m
Reference: Colin J.H. Brenan et al.: “Characterization and use of a novel optical position sensor for microposition control of a linear motor” , Rev. Sci. Instrum. 64(2), February 1993.
Precision Engineering Research Group
Displacement Sensors 2 and 3 in differential configuration
Precision Engineering Research Group
Displacement Sensor 1
Fundamental Principle Animation
Actual Measurement Data
Force error +/- 6.5 % (not to scale)
displacement error +/- 10 nm (not to scale)
Precision Engineering Research Group
Market Potential Precision Engineering Research Group
Bistable microrelay used in automotive applications:
•20 milion cars/year (20*106 relays/year)•5 % of cars/year using it (1*106 relays/year)•20 relays/car/year (20*106 relays/year)•1000 relays/wafer (20*103 wafers/year)•200 days per year=========================================100 wafers/day !