Optoactive polymer actuators and devices (OAPAD) are, undoubtedly, promising technologies. Analytical and finite
element models describing dynamics of photo-induced deformation in OAPADs have already been developed,
particularly for liquid crystal elastomers (LCE). Advanced materials like LCE - Carbon Nanotube (CNT) composites,
require a more complex physical analysis involving different coupled phenomena like photochemistry, photophysics and
chemomechanical coupling. The need for rigorous modeling of such complex physics as well as the imminent
implantation and development of ground-breaking practical OAPADs, demand a fast way to model the light-induced
deformation of the material. The purpose of this work is to build a finite element model serving as a bridge between
basic elastomer physics and device engineering and design. We take advantage of experimental actuation data to build an
empirical model describing the material deformation. The concept that sets the basis of the model is explained: the light
irradiation provokes the heating of the material mainly thanks to the absorption properties of the CNTs. Thus, we can
consider that CNTs behave as internal heat generators. Consequently, an opto-mechanical system based on LCE-CNT
can be evaluated and the mechanical response optimized.
We characterize the monodomain nematic liquid crystal elastomers enriched with the carbon nanotubes (LCE-CNT
composites) with the purpose of general understanding the fundamentals of their mechanical actuation behavior when
illuminated by light and with the final objective to facilitate the design of photo-actuators based on LCE-CNTs. The
parameters like absorption spectra and absorption coefficients of the material as a function of CNTs concentration have
been studied. Temperature-induced three dimensional deformations were compared with the photo-induced deformations
monitored using SEM and conventional optical microscopy techniques, combined with thermal imaging done with the
Over the last few years, several technologies have been adapted for use in tactile displays, such as thermo-pneumatic
actuators, piezoelectric polymers and dielectric elastomers. None of these approaches offers high-performance for
refreshable Braille display system (RBDS), due to considerations of weight, power efficiency and response speed.
Optical actuation offers an attractive alternative to solve limitations of current-art technologies, allowing
electromechanical decoupling, elimination of actuation circuits and remote controllability. Creating these opticallydriven
devices requires liquid crystal - carbon nanotube (LC-CNT) composites that show a reversible shape change in
response to an applied light. This work thus reports on novel opto-actuated Braille dots based on LC-CNT composite and
silicon mold microstamping. The manufacturing approach succeeds on producing blisters according to the Braille
standard for the visually impaired, by taking shear-aligned LC-CNT films and silicon stamps. For this application, we
need to define specifically-shaped structures. Some technologies have succeeded on elastomer microstructuring.
Nevertheless, they are not applicable for LC-CNT molding because they do not consider the stretching of the polymer
which is required for LC-CNT fabrication. Our process demonstrates that composites micro-molding and their 3-D
structuring is feasible by silicon-based stamping. Its work principle involves the mechanical stretching, allowing the LC
Characterization of polymer nanocomposites by electron microscopy has been attempted since last decade. Main drives
for this effort were analysis of dispersion and alignment of fillers in the matrix. Sample preparation, imaging modes and
irradiation conditions became particularly challenging due to the small dimension of the fillers and also to the
mechanical and conductive differences between filler and matrix. To date, no standardized dispersion and alignment
process or characterization procedures exist in the trade. Review of current state of the art on characterization of polymer
nanocomposites suggests that the most innovative electron and ion beam microscopy has not yet been deployed in this
material system. Additionally, recently discovered functionalities of these composites, such as electro and photoactuation
are amenable to the investigation of the atomistic phenomena by in situ transmission electron microscopy. The
possibility of using innovative thinning techniques is presented.
A detailed description of a read-out amplifier for high frequency MEMS resonators is done. Both read-out requirements and circuit architecture are presented. The architecture of the system is mainly based on three blocks: a trans-impedance amplifier, followed by a three-stage voltage-to-voltage amplifier, and finally by an output buffer amplifier. Physical design is based on AMS 0,35 μm technology. Also, simulation and fabrication results are presented and analyzed. Simulation results show an AC transimpedance gain of 70 dBΩ and a cut-off frequency of 400 MHz, for a band-pass bandwidth over 350 MHz. The fabricated amplifier has an input noise current spectral density of 11 pA/(Hz)1/2, a power dissipation of 200 mW, and occupies an active area of 600 μm * 450μm. Integration of read-out circuit with MEMS resonator has been designed and implemented, by properly connection of MEMS signals to the amplifier, in order to enable characterization of a set of MEMS resonators. Integration analysis will allow future extraction of electrical parameters of the resonator.