Biomimetic Based Applications

The interaction between cells, tissues and biomaterial surfaces are the highlights of the book "Biomimetic Based Applications". In this regard the effect of nanostructures and nanotopographies and their effect on the development of a new generation of biomaterials including advanced multifunctional scaffolds for tissue engineering are discussed. The 2 volumes contain articles that cover a wide spectrum of subject matter such as different aspects of the development of scaffolds and coatings with enhanced performance and bioactivity, including investigations of material surface-cell interactions

Novel technologies for studies of structural and functional connections

To understand the mechanisms underlying the correct functioning of an organ it is important to study its architecture and how the interactions between cells are leading to a specific function. Specifically, the connections that form in the brain are related to the pattern of activation that neurons have, and can help to understand what is the function of each region. Combining the structural knowledge with functional studies is crucial to understand how the cells communicate and propagate the depolarization. Another way to understand the mechanisms underlying tissue functionality is to try to replicate its features and inspect if the resulting behavior is similar to the original one. In this thesis I am describing different tools that we developed to inspect the cells connectivity from the architectural and functional point of view, focusing on imaging, analytic and engineering techniques. To inspect the connection within the brain, in paper I we developed a microscopy system capable of performing fast volumetric imaging of large cleared samples (called LSTM, Light Sheet Theta Microscopy). LSTM is built upon the LSM (Light Sheet Microscopy) system, but instead of illuminating the sample from the sides –which leads to a physical constrain to the samples lateral dimension or depth– the light sheet is scanned on the imaging plane from an angle smaller than 90°. Therefore this approach eliminates the constraints on the lateral size without compromising the image quality and speed. Furthermore, it overcomes the LSM limitation that leads to huge scattering on the center part of the sample. In fact, LSTM images each plane with the same intensity leading to homogeneous x-y acquisition throughout the whole dept. This system can help to create maps of long ranging connections of neurons of intact rodents organs (eg brain) and can theoretically be used to acquire un entire human brain, slab by slab, in a reasonable amount of time. In paper II we propose a tool to inspect the evolution of living cultures for an extended period of time. To do so, we developed a mini-microscope to be placed in the incubator that performs long lasting recordings and automatically detects the Regions Of Interest (ROI), calculates the intensity profiles, and compresses the data after every time-point. This system (called XDscope) is designed to limit the user interaction with the culture, minimize the light exposure and to ease the process of getting the desired information out of the experiment and store as little data as possible. Using the XDscope we performed long term monitoring of GCaMP6 expressing neurosphere (NSP) networks for over 2 weeks, showing that the cells behavior is not affected by the long acquisition. Furthermore we used the system to evaluate the uptake mechanism of p-HTMI, an LCO (Luminescent Conjugated Oligothiophene) over the NSP network, showing that the targeted cells are progenitor cells as expected, since the fluorescent cells are mainly located around the spheres. Finally we investigated further the specific target of p-HTMI within the cells performing double labeling with proteins that seemed to be in the targeted area. From the results it seems like GM130/Golga2, a protein that facilitates the transportation between ER and Golgi apparatus has a high percentage of overlap with the molecule. Finally in paper III we tried to mimic the features and the cell spatial arrangement of a leaving tissue to infer similar properties to an engineered construct. We propose an innovative strategy to integrate a patterned gold microelectrode into a flexible biomimetic hybrid actuator with double muscle-like patterned layers made using PEG (Polyethylene Glycol) and CNT-GelMA (Carbon Nano Tubes- Gelatin Methacryloyl). The CNT-GelMA patterned layer acted as a substrate for cell culture to induce maturation of cardiac muscle cells, while the PEG layer acts as the backbone of the whole membrane. The resulting muscle-like biohybrid actuator showed excellent mechanical integrity with an inserted Au microelectrode and advanced electrophysiological functions with strong muscle contractions. Therefore, we successfully fabricated a biomimetic hybrid actuator with muscle-like pattern, and controllable movement under an electrical field produced by integrated electrodes

Exchangeable Liquid Crystalline Elastomers and Their Applications.

This Review presents and discusses the current state of the art in "exchangeable liquid crystalline elastomers", that is, LCE materials utilizing dynamically cross-linked networks capable of reprocessing, reprogramming, and recycling. The focus here is on the chemistry and the specific reaction mechanisms that enable the dynamic bond exchange, of which there is a variety. We compare and contrast these different chemical mechanisms and the key properties of their resulting elastomers. In the conclusion, we discuss the most promising applications that are enabled by dynamic cross-linking and present a summary table: a library of currently available materials and their main characteristics.ERC H202

Cleaning of Floating Photovoltaic Systems: A Critical Review on Approaches from Technical and Economic Perspectives

There are some environmental factors, such as ambient temperature, dust, etc., which cause a reduction in the efficiency of Photovoltaic (PV) systems. Installation of PV panels on the water surface, commonly known as Floating Photovoltaic (FPV) systems, is one solution to employ PV panels in a cooler environment, achieve higher efficiency, and reduce water evaporation. FPV systems open up new opportunities for scaling up solar generating capacity, especially in countries with high population density and valuable lands, as well as countries with high evaporation rates and water resources deficiency. Since the FPV system is an almost new concept, its cleaning techniques have not been comprehensively studied. While FPV systems are located on the surface of water resources and reservoirs, the water quality can limit the application of different cleaning techniques. Therefore, this paper investigates different techniques of FPV systems cleaning and categorizes them into water-based and water-free approaches. In addition, their cleaning frequencies, as well as economic aspects, are presented and discussed to determine their merits and demerits for using them in FPV system

Design, Synthesis and Study of Thermomechanically Active Polymer Networks Based on Latent Crosslinking of Semicrystalline Polymers

Demand has arisen rapidly for smart materials in the world of the need to develop and understand new functional products like plastics, rubber, adhesives, fibers, and coatings. Such products are essentially composed of polymers, large molecules of high molecular weight with homogeneous or various repeating units, which researchers term “macromolecules” that engender specific structural, morphological, and physical and mechanical properties. Those polymers with the capacity to change their configuration in accordance with environmental alteration are specifically referred to as shape memory polymers (SMPs), attracting much interest of study both academically and industrially. Herein, this dissertation aims at design, fabrication, and characterization of novel crosslinkable semicrystalline polymeric materials utilizing different techniques and mechanisms in order to explore their special thermomechanical features as well as the possibilities for potential industrial application based on shape memory (SM) effects. Key aspects include use of modern polymer synthesis to tailor thermal and shape memory properties and the adoption of electrospinning processing techniques to form continuous, fine fibers that allow unique molecular modifications, study of enzymatic degradation behavior involving physical form and microstructural state, and unprecedented approaches of making new kinds of shape memory assisted self-healing (SMASH) materials and thermal-responsive self-reversible actuators that require no human intervention. In the following is described the dissertation scope and organization. Chapter 1 goes over background relating to material science within the scope of SM material, self-healing (SH) material, and actuators. Chapter 2 outlines research conducted to achieve new compositions of matter and post-synthesis process, along with supporting characterization for the development of novel SMP materials with featuring tunable reversible actuation capability under ambient stimulus. We prepared a family of crosslinkable (unsaturated), semicrystalline cyclooctene (CO)-based copolymers with varying second monomer and composition via ring opening metathesis polymerization (ROMP). The unsaturation enables covalent crosslinking of polymer chains, in the presence of select thermal initiator through compression molding, allowing subsequent formation of a temperature-responsive network that shows a reversible two-way shape memory (2WSM) effect, indicative of crystallization-induced elongation upon cooling and melting-induced contraction upon heating when a constant, external stress is applied. Molecular, thermomechanical, and SM experiments were performed to investigate and tune the reversible actuation of aforementioned copolymers for the purpose of yielding quantitative guidelines for tailoring material and actuation performance through variations in composition and process. Chapter 3 seeks a latent-crosslinkable, mechanically flexible, fully thermoplastic shape memory polymer. Towards this end, we have developed a simple but effective macromolecular design that includes pendent crosslinking sites via the chain extender of a polyurethane architecture bearing semicrystalline poly(ε-caprolactone) (PCL) soft segment. This new composition was used to prepare fibrous mats by electrospinning and films by solvent casting, each containing thermal initiators for chemical crosslinking. Relevant to medical applications, in vitro enzymatic degradation experiments were carried out to understand the effect of crosslinking state and crystalline structure on degradation behavior of the materials. Chapter 4 builds upon the results of Chapter 3, reporting on the design, fabrication and characterization of a novel, electrospun SMASH polymer blend that incorporates the aforementioned latent-crosslinkable polyurethane. This unique blend system has been unprecedentedly developed by employing a solution in which crosslinkable polyurethane and linear polyurethane are mixed homogeneously for electrospinning. After preparing a family of blends with varying compositions, comprehensive characterizations and various healing tests were done to determine optimal healing performance. Further, the effect of different damage types and molecular anisotropy (nanofibers aligned in high speeds during electrospinning process) were studied for their effect on healing performance. Chapter 5 continues along the line of Chapter 3, presenting the fabrication and testing of novel, electrospun SMP composites that were designed to exploit molecular and geometric anisotropy in reversible actuation under external stress-free condition upon change in ambient temperature. More specifically, the SMP composites consist of two electrospinnable constituents, one being the aforementioned latent crosslinkable polyurethane that serves to shape fixing and recovery (SM properties), and the other being a thermoplastic elastomer known as Pellethane that provides the internal stress field needed for 2WSM to occur. Multiple designs were developed and investigated in this chapter, in particular, including uniaxial actuator, bending actuator, and twisting actuator along with their bench demonstration of self-reversible actuation. Chapter 6 discusses the overall dissertation conclusions, followed descriptions of suggestions for future work, some of which are sub-sectioned at the end of this dissertation

Study of soft polymer actuators driven by an order-disorder phase transition

Les actionneurs souples à base de polymère pouvant être actionnés de manière réversible suscitent un grand intérêt car ils peuvent être construits à partir d’une vaste source de polymères et être déclenchés par divers types de stimuli pour la production répétée de travaux physiques. Parmi ceux-ci, les actionneurs thermo-sensibles et photo-sensibles à base de polymères semi-cristallins (SCPs) et / ou de polymères à cristaux liquides (LCPs) se développent rapidement en raison de leurs applications potentielles en tant que dispositifs intelligents dans de nombreux domaines. Les chercheurs ont consacré des efforts considérables ces dernières années à la mise au point de nouveaux matériaux et de nouvelles fonctions basés sur les SCPs et les LCPs, mais la demande de construction d'actionneurs en polymère robustes dotés de fonctions avancées utilisant des matériaux facilement disponibles et des stratégies faciles n'a pas été satisfaite. Le but principal de cette thèse est de développer et d’étudier de tels actionneurs polymères fonctionnels avancés et contrôlables thermiquement ou par la lumière afin de produire de l’énergie mécanique par un actionnement réversible, en utilisant du poly (éthylène-acétate de vinyle) (EVA) semi-cristallin disponible dans le commerce et un type de LCP photoréticulable avec addition de petites quantités d'additifs générant de la chaleur. Nos approches étaient simples, pratiques et robustes, car nous n’avions utilisé qu’un laser ou un substrat isothermique pour réguler plusieurs comportements d’actionnement réversibles de pointe. L’utilisation d’EVA a donné lieu à deux projets présentés dans les chapitres 1 et 2, respectivement, en tant que première partie de cette thèse. Dans cette partie, deux comportements d'actionnement réversibles ont été décrits. Le premier est contrôlé par une commutation marche / arrêt du laser, tandis que le second est auto-entretenu sur un substrat isotherme. Les deux comportements sont associés à un gradient de température établi dans la direction de l'épaisseur de l'actionneur et entraîné par une transition de phase cristallisation – fusion. La deuxième partie est présentée au chapitre 3 et démontre qu'une bande de LCP monolithique réticulée de manière non uniforme peut fonctionner comme un photoactionneur multifonctionnel commandé par une transition de phase LC – isotrope. Dans le premier chapitre, nous avons préparé un type d'actionneur optique contenant des nanoparticules d'or basé sur une bande d'EVA étirée recevant des cristallites orientés. Lors de l'irradiation avec un laser (longueur d'onde de 532 nm), la résonance plasmonique de surface (SPR) de nanoparticules d'or (AuNP) est activée pour libérer de la chaleur qui fond partiellement les cristallites à Tlight. Les cristallites dont la température de fusion (Tm) est inférieure à Tlight sont fondus en tant que domaine d'actionnement afin de contracter la bande de manière asymétrique en raison du gradient de température, tandis que les cristaux de Tm supérieurs à Tlight soutiennent en tant que cadre. Lorsque le laser est retiré, la recristallisation orientée du domaine d’actionnement induit une expansion dans la direction d’étirage pour détendre la bande. Les résultats montrent que la luminosité, la force mécanique optique, l'amplitude d'actionnement et la vitesse d'activation peuvent être réglés en ajustant l'intensité du laser, le contenu en AuNPs, l'allongement et l'épaisseur de l'actionneur. Une application potentielle de l'actionneur optique en tant que commutateur sans fil et contrôlable à distance a été démontrée. Dans le deuxième chapitre, nous avons démontré le mouvement autonome sans précédent d’une bande d’EVA déposée sur un substrat en acier isotherme. La bande est fabriquée à partir d'EVA pur réticulé contenant des cristallites alignés de manière uniaxiale. Une fois en contact avec le substrat chaud, un gradient de température est immédiatement établi sur toute l'épaisseur et élève la section médiane de la bande en arc, provoqué par la contraction induite par la fusion asymétrique. Dans l'air, une recristallisation dirigée se produit et dilate la bande pour retomber à la forme plate initiale. Dans cet état, le substrat chaud chauffe la bande pour qu'elle se plie à nouveau afin de répéter le cycle de mouvement précédent. Une boucle de rétroaction thermo-mécanique-thermique est ainsi facilement établie et validée pour commander le mouvement continu, qui peut durer une heure ou environ 1 000 cycles. Nous avons étudié les facteurs qui affectent l'amplitude et la période du mouvement autonome et avons constaté que la température du substrat et l'allongement de la bande sont des paramètres importants, tandis que la durabilité est principalement altérée par le contact de plus en plus étroit entre la bande et le substrat. Le potentiel de conversion de l’énergie thermique en énergie mécanique a été démontré par une fonction d’auto-marche et la capacité de promouvoir la rotation d’une roue. Dans le troisième chapitre, un photoactionneur à base de LCP contenant un colorant proche infrarouge (NIR) a été préparé par photoréticulation d’une bande de LCP alignée de manière uniaxiale d’un côté en monodomaine et de l’autre en polydomaine LC relaxée. L'actionneur est multifonctionnel et remplit trois fonctions: le transport guidé par la lumière, la rotation flexible en locomotion et le mouvement autonome. Avec deux extrémités confinées sur un substrat et maintenues à plat, la bande peut générer une bosse sur le site de l'irradiation laser, résultant du réarrangement des chaînes polymères lors de la contraction iso-contrainte à l'état isotrope et du passage ultérieur à l'état LC. Une cargaison en forme de tige placée à côté de la bosse peut être transportée de bout en bout lorsque la bosse se propage sous balayage laser. Avec une extrémité fixée sur le substrat et l’autre libérée dans l’air, la bande soumise à une irradiation laser constante peut exécuter un mouvement auto-entretenu selon plusieurs modes, qui sont dictés par l’angle incident du laser. Le mouvement autonome est basé sur le mécanisme d’observation automatique et piloté par le retour photo-thermo-mécano-thermique. Numériser la bosse découpée de la bande de manière uniforme avec le laser peut faire en sorte que la bosse rampe directement sur les surfaces horizontales et inclinées, tandis qu'un balayage asymétrique peut guider le sens de rotation avec souplesse.Abstract: Polymer-based soft actuators capable of reversible actuation are attracting wide interest and attention as they can be constructed from a broad range of polymers and triggered by various types of stimuli to output physical work repeatedly. Among them, thermoresponsive and photoresponsive actuators based on semicrystalline polymers (SCPs) and liquid crystalline polymers (LCPs) are increasingly developed due to their potential applications as smart devices in numerous fields. In recent years, massive efforts have been devoted by researchers to developing new materials and functions based on SCPs and LCPs, but the demand for constructing robust polymer actuators with advanced functions using readily available materials and facile strategies has not been fulfilled. The main purpose of this thesis is to develop and study such advanced and functional polymer actuators controllable by thermal or light to output mechanical energy through reversible actuation, using commercially available semicrystalline poly(ethylene-co-vinyl acetate) (EVA) and a type of photocrosslinkable LCP with addition of small amounts of heat-generating additives. Our approaches are simple, convenient and robust as we only use a laser or an isothermal substrate to regulate several leading-edge reversible actuation behaviors. The use of EVA elicited two projects which are presented in Chapter 1 and Chapter 2, respectively, as the first part of this thesis. In this part, two reversible actuation behaviors were described. The first one is controlled by on/off switching of the laser, while the second one is self-sustained on an isothermal substrate surface. Both behaviors are associated with a temperature gradient established in the thickness direction of the actuator and driven by melting–crystallization phase transition. The second part of this thesis, presented in Chapter 3, deals with an LCP actuator. We show that a monolithic LCP strip crosslinked non-uniformly can perform as a multifunctional photoactuator driven by LC–isotropic phase transition. In the first chapter, we prepared a type of gold nanoparticle-containing optical actuator based on a stretched EVA strip accommodating oriented crystallites. Upon irradiation with a laser (532 nm in wavelength), surface plasmon resonance (SPR) of gold nanoparticles (AuNPs) is activated to release heat that partially melts the crystallites at Tlight. The crystallites with their melting temperature (Tm) below Tlight are melted as the actuation domain that bends the strip towards the laser direction as a result of uneven contraction forces along the thickness due to the temperature gradient, while the crystallites with Tm higher than Tlight sustain as the framework. When the laser is removed, oriented recrystallization in the actuation domain induces expansion along the stretching direction to unbend the strip. Results show that Tlight, the photomechanical force, the actuation magnitude and the actuation speed are tunable by adjusting the laser intensity, the content of AuNPs, the elongation and thickness of the actuator. A potential application of the optical actuator as a wireless and remotely controllable switch was demonstrated. In the second chapter, we demonstrate an unprecedented autonomous motion of an EVA strip deposited on an isothermal steel substrate. The strip is made from crosslinked pure EVA containing uniaxially aligned crystallites. Once in contact with the hot substrate, a temperature gradient is immediately established across the thickness and elevates the middle section of the strip to form an arch, caused by the melting-induced-contraction of the bottom side of the strip. Once in the air, the melted EVA chains are cooled and recrystallize, which generates opposite extensional force on the bottom side and brings the strip to fall back to the initial flat shape. In this state, the hot substrate heats the strip to bend it again, and the arching up and flattening down motion cycle is repeated. A thermo-mechanical-thermal feedback loop is thus easily established to drive the self-sustained motion, which can last hour-long or around 1000 cycles. We investigated the factors that affect the amplitude and period of the autonomous motion and found that both the substrate temperature and elongation of the strip are important parameters, while the durability is mainly decayed by the looser and looser contact between the strip and the substrate. Potential of converting thermal energy to mechanical energy was demonstrated by a self-walking function and the ability to promote the rotation of a wheel. In the third chapter, a multifunctional LCP-based photoactuator containing a near-infrared (NIR) dye is described. It was prepared by photocrosslinking a uniaxially aligned LCP strip on one side in monodomain and the other side in relaxed LC polydomain. The actuator has three functions, which are the light-guided transportation, flexible turning in locomotion and autonomous motion. First, with its two ends fixed on a substrate and kept flat, the strip can generate a bump at the site of laser irradiation, arising from polymer chains rearrangement during isostrain contraction in isotropic state and subsequent transition to LC state. A rod-shape cargo put beside the bump can be conveyed from end to end as the bump propagates under laser scanning. Secondly, with one end fixed on the substrate and the other released in air, the strip under constant laser irradiation can execute self-sustained motion in multiple modes, which are dictated by the incident angle of the laser. The autonomous motion is based on a self-shadowing mechanism and driven by the photothermo-mechano-thermal feedback. Thirdly, scanning the bump cut from the strip uniformly, with the two ends free, laser scanning can make the actuator crawl straightly on both horizontal and inclined surfaces, while unsymmetrical laser scanning can guide the turning direction in its movement

Piezoelectric Transducers Based on Aluminum Nitride and Polyimide for Tactile Applications

The development of micro systems with smart sensing capabilities is paving the way to progresses in the technology for humanoid robotics. The importance of sensory feedback has been recognized the enabler of a high degree of autonomy for robotic systems. In tactile applications, it can be exploited not only to avoid objects slipping during their manipulation but also to allow safe interaction with humans and unknown objects and environments. In order to ensure the minimal deformation of an object during subtle manipulation tasks, information not only on contact forces between the object and fingers but also on contact geometry and contact friction characteristics has to be provided. Touch, unlike other senses, is a critical component that plays a fundamental role in dexterous manipulation capabilities and in the evaluation of objects properties such as type of material, shape, texture, stiffness, which is not easily possible by vision alone. Understanding of unstructured environments is made possible by touch through the determination of stress distribution in the surrounding area of physical contact. To this aim, tactile sensing and pressure detection systems should be integrated as an artificial tactile system. As illustrated in the Chapter I, the role of external stimuli detection in humans is provided by a great number of sensorial receptors: they are specialized endings whose structure and location in the skin determine their specific signal transmission characteristics. Especially, mechanoreceptors are specialized in the conversion of the mechanical deformations caused by force, vibration or slip on skin into electrical nerve impulses which are processed and encoded by the central nervous system. Highly miniaturized systems based on MEMS technology seem to imitate properly the large number of fast responsive mechanoreceptors present in human skin. Moreover, an artificial electronic skin should be lightweight, flexible, soft and wearable and it should be fabricated with compliant materials. In this respect a big challenge of bio-inspired technologies is the efficient application of flexible active materials to convert the mechanical pressure or stress into a usable electric signal (voltage or current). In the emerging field of soft active materials, able of large deformation, piezoelectrics have been recognized as a really promising and attractive material in both sensing and actuation applications. As outlined in Chapter II, there is a wide choice of materials and material forms (ceramics: PZT; polycrystalline films: ZnO, AlN; polymers and copolymers: PVDF, PVDF-TrFe) which are actively piezoelectric and exhibit features more or less attractive. Among them, aluminum nitride is a promising piezoelectric material for flexible technology. It has moderate piezoelectric coefficient, when available in c-axis oriented polycrystalline columnar structure, but, at same time, it exhibits low dielectric constant, high temperature stability, large band gap, large electrical resistivity, high breakdown voltage and low dielectric loss which make it suitable for transducers and high thermal conductivity which implies low thermal drifts. The high chemical stability allows AlN to be used in humid environments. Moreover, all the above properties and its deposition method make AlN compatible with CMOS technology. Exploiting the features of the AlN, three-dimensional AlN dome-shaped cells, embedded between two metal electrodes, are proposed in this thesis. They are fabricated on general purpose Kapton™ substrate, exploiting the flexibility of the polymer and the electrical stability of the semiconductor at the same time. As matter of fact, the crystalline layers release a compressive stress over the polymer, generating three-dimensional structures with reduced stiffness, compared to the semiconductor materials. In Chapter III, a mathematical model to calculate the residual stresses which arise because of mismatch in coefficient of thermal expansion between layers and because of mismatch in lattice constants between the substrate and the epitaxially grown films is adopted. The theoretical equation is then used to evaluate the dependence of geometrical features of the fabricated three-dimensional structures on compressive residual stress. Moreover, FEM simulations and theoretical models analysis are developed in order to qualitative explore the operation principle of curved membranes, which are labelled dome-shaped diaphragm transducers (DSDT), both as sensors and as piezo-actuators and for the related design optimization. For the reliability of the proposed device as a force/pressure sensor and piezo-actuator, an exhaustive electromechanical characterization of the devices is carried out. A complete description of the microfabrication processes is also provided. As shown in Chapter IV, standard microfabrication techniques are employed to fabricate the array of DSDTs. The overall microfabrication process involves deposition of metal and piezoelectric films, photolithography and plasma-based dry and wet etching to pattern thin films with the desired features. The DSDT devices are designed and developed according to FEM and theoretical analysis and following the typical requirements of force/pressure systems for tactile applications. Experimental analyses are also accomplished to extract the relationship between the compressive residual stress due to the aluminum nitride and the geometries of the devices. They reveal different deformations, proving the dependence of the geometrical features of the three-dimensional structures on residual stress. Moreover, electrical characterization is performed to determine capacitance and impedance of the DSDTs and to experimentally calculate the relative dielectric constant of sputtered AlN piezoelectric film. In order to investigate the mechanical behaviour of the curved circular transducers, a characterization of the flexural deflection modes of the DSDT membranes is carried out. The natural frequency of vibrations and the corresponding displacements are measured by a Laser Doppler Vibrometer when a suitable oscillating voltage, with known amplitude, is applied to drive the piezo-DSDTs. Finally, being developed for tactile sensing purpose, the proposed technology is tested in order to explore the electromechanical response of the device when impulsive dynamic and/or long static forces are applied. The study on the impulsive dynamic and long static stimuli detection is then performed by using an ad hoc setup measuring both the applied loading forces and the corresponding generated voltage and capacitance variation. These measurements allow a thorough test of the sensing abilities of the AlN-based DSDT cells. Finally, as stated in Chapter V, the proposed technology exhibits an improved electromechanical coupling with higher mechanical deformation per unit energy compared with the conventional plate structures, when the devices are used as piezo-actuator. On the other hand, it is well suited to realize large area tactile sensors for robotics applications, opening up new perspectives to the development of latest generation biomimetic sensors and allowing the design and the fabrication of miniaturized devices