p recision e ngineering r esearch g roup

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

Snap Through of Bistable Beam 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 (parts mostly made with the waterjet) Precision Engineering

Research Group

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

Pictures of Prober Tips Precision Engineering Research Group

Flextester

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 !