me3281 lab question paper

8/12/2019 ME3281 Lab Question Paper

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Assignment (laboratory session)

Objective:

Assignment (laboratory session) is designed to maximize the students understanding of the basics of a

microfabricated resonator - one of the key elements that make up todays micro systems.

Device:

Fig .1 !er!ie" of the de!ice layout

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Anchors

'o!able fingers

- m

Anchor

.% m

.% m

$ m

$. m

- m

123 movable comb fingers on each side (top &

bottom)

1$&% m

1

&.&m

1& m

.%m

/ength0 1 m2 3idth m2

4hickness0 $ m2

1 m

% m

5 m

% m

Area0

6%57 m$


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4he de!ice to be tested is a '8'-dri!en micro gyroscope "ith optical readout. 4he gyroscope is

dri!en electrostatically "ith a comb-dri!e resonator. *n this experiment7 "e "ill focus on the fre9uency

characteristics of the '8' comb-dri!e resonator. :ey dimensions of the resonator are sho"n in the

abo!e figures0 (4hickness of the structure is $ m7 gap spacing bet"een the structure and substrate is $

m). 'ore details can be found in the de!ice layout design0 ;4esting$. ?ra" a mechanical e9ui!alent model of the microresonator. @i!en a polysilicon structure

thickness of $ m7 oungs 'odulus of 1.6% B 1%11Ca7 material density of $% kgDm7 and

!iscosity of the air of 1. B 1%- sDm$7 estimate the e9ui!alent spring constant7 mass7 and

damping coefficient of the model.

>. 8stimate the resonant fre9uency and > factor of the resonator.

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Session 2: estin! of microresonator ("ab Session)

@eneral teps0

1. #arefully put the de!ice on the probe station7 adEust the microscope7 and !isually check the de!ice.

$. Align and position the probes under the microscope7 place them carefully on the bonding pads7 and

make sure they are electrically connected to the pads.

. #onnect the probes to the signal generators and !oltage sources.

&. 4urn on the C#7 and run the image capturing soft"are.

. #apture the de!ice image under operation7 and measure the !ibration amplitude and record.

>&. ingle-side dri!ing

#onnect the signal generators and !oltage sources according to the follo"ing schematic diagram.

Apply bG % olts7 and acG %cos($ft) olts. can the fre9uencyffrom kHz to :Hz "ith

incremental steps of 1%% Hz. At each dri!ing fre9uency7 record the !ibration amplitude of the de!ice.

Ieport your experimental results and explain the phenomenon obser!ed.

Comb

Drive

Ground PlaneFolded-beamFlexure

Vb

Movable

Shuttle

CoriolisSensing

Vac

Fig. 'icro resonator single-side dri!ing mechanism

>. Cush-pull dri!ing

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#onnect the signal generators and !oltage sources according to the follo"ing schematic diagram.

Apply bG % olts7 ac1G 1%cos($ft) olts and ac$G 1%cos($ftJ1%) olts. can the fre9uencyf

from kHz to :Hz "ith incremental steps of 1%% Hz. At each dri!ing fre9uency7 record the !ibration

amplitude of the de!ice. Ieport your experimental results and explain phenomenon obser!ed.

Comb

Drive

Ground PlaneFolded-beamFlexure

Vb

Movable

Shuttle

CoriolisSensing

Vac1 Vac2

Fig.& 'icro resonator push-pull dri!ing mechanism

>6. Ieport the experimental resonant fre9uency and >-factor of the de!ice.

>K. Are there any discrepancies bet"een the analytical and experimental resultsL 8xplain.

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me3281 lab question paper

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