micro stereo lithography

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presentedby

a a

IITKharagpur

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ob ects

Micro

stereolithography is

useful

for

instantaneous

Packagingofsensorsetc.

cromo ng

as

master

pattern

Microdevices

Biomedical

Microrobotics

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Im lementation

Point

by

point

or

line

by

line

scanning

technique o e ayer nonego w t t e e po act vemas

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MiniatureSizeControl

XY

Plane :

by

laser/lightsource

Zdirection :

Controlthepenetrationdepth

andtherebythe

cur ng ept o eachpolymerised

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MiniatureSizeControlAworkingcurveforcontrollingcuringdepthinSLbasedonthephotopolymers

thresholdexposure:

Cd =Dpln(E/Ec),where Cd=thecuringdepth, = aserpower Ec =thresholdpowerforpolymerizationtooccur, Dp =thepenetrationdepthofthelaserintothesolution,

Dp isdefinedviatheBeerLambertlawas:

Dp =1/{2.3(I[I]

+UVA[UVA])}

w ere I= molarextinctioncoefficientoftheinitiator, [I]=initiatorconcentration, UVA=molarextinctioncoefficientoftheUVabsorber [UVA]=UVabsorberconcentration.

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ACOUSTOOPTIC

MODULATOR

n sanacous oop c crys aw erethelightpassingthroughthecrystalis

diffractedor

transmitted

depending

on

the

.

Whenthefixedfrequencydrivesignalis

thesignal

is

off

the

light

passes

through

the

crystalwithoutdiffraction.

Theamountoflightdiffracteddependson

the

amplitude

of

the

drive

signal.

Thedrivesignalisgeneratedfromthepatterntobeexposed.Bycontrollingthe

ofthe

exposure

beam

is

controlled.

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cous o

p c

o u a or

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AcoustoOptic

Deflector

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gratinggenerated

by

an

acoustic

wave

inside

asolid

medium.

Thecompressionandrarefactionsofmediumgeneratedbytheacousticwaveproduceaperiodicindexvariationandformaphasegrating.

Alaserbeamisdiffractedaccordingtothegratingformulam. =

2d

sin

wheremisaninteger, thewavelengthoflaser,anddisthegratingspacing.

Ifthewavelengths oftheacousticwaveisequaltod,the

diffraction

condition

for

m=1

becomessin = /2s Foranacousticwavelengthofabout103 m,thediffractionorder

istypica yont eor ero 103 ra . Thediffractionangleofthelaserbeamischangedwhen

frequencyof

the

acoustic

wave

is

swept

from

f1to

f2

Acousto OpticalDeflector isusefulwhen ScanFieldissmall HighScanRateandRandomaccessibilityisimportant.

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di italmirrordevice

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PhotographsoftheintegratedmicrostereolithographyprototypeapparatusdevelopedatEPFL,Switzerland

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Features

Objectsmadeofafewhundredtoafewthousandsoflayers

About3to6layersperminute,whichcorrespondstoanaverage

of1.5

mm

per

hour.

Thisdevelopedsystemconsistsofeightelements: AComputerAidedDesignenvironmentsupportingsolidor

surfacemodellin ;

Aresin

bath

with

an

integrated

high

resolution

translation

stage

andcomponentbuiltplatform; . Anopticalshutter;

Adiffractive

optical

element

designed

to

re

distribute

the

rra anceo e aser eam roma auss an oa op a pro e; Apolysilicon thinfilmtwistednematic SVGAresolution(800

multipliedby600)spatiallightmodulator; Amultielementlithographicreductionlenssystem;and a

comprehensivecontrol

system.

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Ste s

Each

layer

image

of

object

is

transferred

to

the

Digital

resin

illuminated

resintocreatethenext10mlayerontopofthe

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Ca abilities

Process

time

2

3

hour

per

object as ess process

Layerbylayerfabricationofmicrostructuresby

pro ect on

o

s ce

magescreate

rom

3

computerdesign

tan ar e ormatrequ re

10

m

resolution;

lateral

and

verticalMaximumfieldsize10.24mmx7.68mm

Structuralhei htseveralmillimeters

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g ta

crom rror ev ce MEMSdevicedevelopedatTexasInstruments,in1987

ADMDchiphasonitssurfaceseveralhundred

thousand

microscopic

mirrors

arranged

in

a

rectan ulararra

which

corres ond

to

the

ixels

in

the

imagetobedisplayed.

MirrorsareofthinfilmofAluminiumalloyof16micronacross.

Thenumber

of

mirrors

corresponds

to

the

resolution

of

theprojectedimage.800x600,1024x768,1280x720

Themirrorscanbeindividuallyrotated1012,toanonoroffstate.

eitherthroughthelensorontoaheatsink (calledalightdump).

Two airsofelectrodescontrol ositionofmirrorb electrostaticattraction.

Capableof

operation

for

100000

hours

without

failure

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Di italMicromirror Device DMDThedigitalmicromirrordevice

is

amicro

electromechanicalsystems(MEMS)arrayofa um n um a oymicromirrors,

monolithicall inte ratedontoandcontrolledbyanunderlyingsiliconCMOS

-

memory(SRAM)array

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Creationofshadesb DMDTherapidrepositioningof

switchingbetween'on'and'off')allowstheDMD

to

vary

the

intensity

of

the

lightbeingreflectedout,

shadesofgreyinaddition

towhite

mirror

in

'on'

Top down view of landed mirrors

position)andblack(mirrorin'off'position).

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conventionalstereolitho ra h

Testcom onentmadewithaconventionalstereolithography

machine

Testcomponentmadewithsmallspot

technologyby

Proform Test

com onent

made

of

AG microstereolithography

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A lications

Scale model of a small car, madeof 673 layers of 5 micron each

Three interwoven springshaving smooth surfaces

Part of a hearing aid Double-end connector fluidic

pipes for cell-bilogy applications

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micro stereo lithography

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