Smart Opto-mechanical actuators for tactile applications

290 Pages·2016·6.54 MB·English

Smart Opto-mechanical actuators
for tactile applications
Nu´ria Torras Andre´s
MicroelectronicsandElectronicSystemsDepartment
UniversitatAuto`nomadeBarcelona
Athesissubmittedforthedegreeof
PhilosophiæDoctor(PhD)inEngineering
September2014
ii
El Prof. Jaume Esteve Tinto´, professor d’investigacio´ de l’Institut de Micro-
electro`nica de Barcelona, IMB-CNM (CSIC), i el Dr. Jordi Roig de Za´rate, titular
d’universitatdelaUniversitatAuto`nomadeBarcelona,
CERTIFIQUEN:
que la memo`ria de la present tesi doctoral titulada “Smart Opto-mechanical ac-
tuators for tactile applications” presentada per Nu´ria Torras Andre´s per a optar al
graudeDoctoraenEnginyeriaperlaUniversitatAuto`nomadeBarcelonahaestatre-
alizadasotalasevadireccio´ ituteladinsdelprogramadedoctoratenMicroelectro`nica
iSistemeselectro`nicsdelaUniversitatAuto`nomadeBarcelona.
Bellaterra,
Setembre2014
Laautora:
Nu´riaTorrasAndre´s
DirectorsdeTesi:
Prof. JaumeEsteveTino´ Dr. JordiRoigdeZa´rate.
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Resum
La discapacitat visual e´s una greu amenac¸a que limita la capacitat de
les persones per comunicar-se. Amb els anys, s’han explorat diverses
propostes tecnolo`giques basades tan en est´ımuls auditius com ta`ctils per
aportar solucions reals a la gent que pateix aquest tipus de discapacitat.
Entre les me´s rellevants destaquen les te`cniques d’audiodescripcio´ i els
dispositius Braille basats en actuacio´ piezoele`ctrica, que so`n els que
actualmentestrobenalmercat.
Adiad’avui,alvellmigdelacursatecnolo`gica,hihaunademandacreixent
de comunicacio´ rica i fluida mitjanc¸ant el tacte. Tan e´s aix´ı que la majoria
interruptors, botons i tecles de gran part dels dispositius electro`nics del
nostreentornestanessentsubstitu¨ıtsperpantallesta`ctils, afegintbarreres
f´ısiquesiaugmentantlesdificultatsdecomunicacio´ delespersonescegues.
Novesgeneracionsdematerials,principalmentelspol´ımers,handespertat
ungranintere`senelsdarrersanysgra`ciesalessevesatractivespropietats,
que poden adaptar-se a la carta en funcio´ de les necessitats. De tots
ells, els elasto`mers de cristalls l´ıquids, LCE, en so´n un clar exemple. Els
LCE tenen la capacitat intr´ınseca d’auto-organitzar-se a nivell molecular,
desencadenant canvis controlats i totalment reversibles en les seves
dimensionsaescalamacrosco`pica,enrespostaadiversostipusd’est´ımuls
externs;canvisquepodenadaptar-seperdesenvoluparactuadorscapac¸os
deproduirtanesforc¸osmeca`nicsdetraccio´ comd’empenta.
Larecercapresentadaenaquestatesidescriulesprincipalscaracter´ıstiques
delsLCEdesdelpuntdevistadel’enginyeriaidiscuteixlessevespossibles
aplicacionscomaactuadors,ambelprincipalobjectiud’aportarsolucions
innovadores als actuals sistemes ta`ctils, a partir del disseny, fabricacio´ i
caracteritzacio´ dediferentsactuadorsbasatsenaquestsmaterialsilaseva
foto-actuacio´ a partir de llum visible. Propostes que combinen te`cniques
de processament de materials i tecnologia de microsistemes per aportar
solucionstecnolo`giquesinnovadorescapaunanovageneracio´ d’actuadors
⋅
intelligents.
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Abstract
Visual disability is a serious threat that limits the persons’ ability to
communicate. Over the years several attempts for the development of
technologies based on audio and tactile stimuli have been explored to
provide real solutions to individuals with this disability. Among them,
audio description techniques and Braille devices based on piezoelectric
actuationarethemostrelevantsolutionsonthemarket.
Nowadays, with all the technological improvements, there is a growing
demand for rich communication through touch. Thus switches, buttons
and keyboards of most commonly used electrical devices are being
replaced by tactile displays, adding new physical barriers and increasing
ffi
communicationsdi cultiesofblindpeople.
New generation of materials, especially soft polymer composites, have
beenofincreasedinterestinthelastfewyearsduetotheirmanyattractive
properties, which can be tailored on demand to achieve a broad range
of requirements. Liquid-crystalline elastomers, LCE, are a clear example.
Such materials possess the intrinsic ability to self-organize at molecular
level resulting in a controllable and fully reversible change on their
dimensions at macroscale in response to applied external stimuli, which
can be easily adapted to make actuators producing pulling or pushing
forces.
The research presented in this thesis describes the main characteristics of
LCEmaterialsfromengineeringpointofviewanddiscussestheirpotential
applications as actuators with the main objective to provide innovative
solutions towards current tactile available systems, through the design,
ff
fabricationandcharacterizationofdi erentactuatorapproachesbasedon
these interesting elastomeric materials and their photo-induced actuation
using visible light. Novel approaches combining material processing
techniques and microsystems technology to provide original solutions
towardsanewgenerationofsmartactuators.
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Alamevafam´ılia
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