Showing papers in "Advances in Science and Technology in 2008"
TL;DR: In this article, the similarities and main differences between the two types of magnetically controllable fluids are outlined and exemplified in the paper and chemical synthesis and structural characterization of magnetizable fluids for engineering and biomedical applications are thoroughly discussed.
Abstract: Composition, synthesis and structural properties of ferrofluids and magnetorheological fluids are reviewed and compared. The similarities and main differences between the two types of magnetically controllable fluids are outlined and exemplified in the paper. Chemical synthesis and structural characterization of magnetizable fluids for engineering and biomedical applications are thoroughly discussed.
85 citations
TL;DR: Thermally, light-, and magnetically induced shape-memory polymers, that were developed especially for minimally invasive surgery and other biomedical applications, are presented and triple-shape polymers will be introduced, that have the capability to perform two subsequent shape changes, enabling more complex movements of a polymeric material.
Abstract: Most polymers used in clinical applications today are materials that have been developed originally for application areas other than biomedicine. On the other side, different biomedical applications are demanding different combinations of material properties and functionalities. Compared to the intrinsic material properties, a functionality is not given by nature but result from the combination of the polymer architecture and a suitable process. Examples for functionalities that play a prominent role in the development of multifunctional polymers for medical applications are biofunctionality (e.g. cell or tissue specificity), degradability, or shape-memory functionality. In this sense, an important aim for developing multifunctional polymers is tailoring of biomaterials for specific biomedical applications. Here the traditional approach, which is designing a single new homo- or copolymer, reaches its limits. The strategy, that is applied here, is the development of polymer systems whose macroscopic properties can be tailored over a wide range by variation of molecular parameters. The Shape-memory capability of a material is its ability to trigger a predefined shape change by exposure to an external stimulus. A change in shape initiated by heat is called thermally-induced shape-memory effect. Thermally, light-, and magnetically induced shape-memory polymers will be presented, that were developed especially for minimally invasive surgery and other biomedical applications. Furthermore triple-shape polymers will be introduced, that have the capability to perform two subsequent shape changes. Thus enabling more complex movements of a polymeric material.
76 citations
TL;DR: In this paper, a specific assembly with embroidered wiring and embroidered interconnections has been developed and improved, and two different encapsulation technologies have been developed for this assembly.
Abstract: This document explains different approaches to integrating electronics in textiles. It discusses reliability standards and tests for electronics in textiles. Encapsulation technologies are evaluated concerning their applicability in textile integrated electronics. Furthermore a specific assembly with embroidered wiring and embroidered interconnections has been developed and improved. Two different encapsulation technologies have been developed for this assembly. Standardized tests have been carried out to assess the reliability of the assembly and its encapsulations. Finally the achievements are critically discussed.
72 citations
TL;DR: In this paper, an optical sensing system that can be integrated in a wound dressing patch has been designed, including a white light source (LED), and a spectrometer for detection.
Abstract: Continuous health monitoring often requires hospitalization, which can become an expensive and inconvenient choice for the patient. In this perspective, wearable sensors that allow in situ biosensing constitute a very promising technology. This work aims to develop immunosensors for continuous monitoring of the wound healing process, based on pH changes, as well as on the concentrations of inflammatory proteins such as the C-reactive protein (CRP). Sensing principles include the use of responsive hydrogels that swell in response to changes in the surroundings, and the use of functional surfaces that specifically recognize the target protein. The detection principle is based on an optical signal, using the evanescent field of light propagating along a waveguide, probing refractive index changes. An optical sensing system that can be integrated in a wound dressing patch has been designed, including a white light source (LED), and a spectrometer for detection. The sensor was successfully tested in the laboratory with biological samples (blood serum), demonstrating reversible pH measurements between pH 6-8, and detection of changes in the concentration of CRP between 1 and 100 μg/ml. The sensor will later be integrated into wound dressings or bandages, forming a sensing patch that is connected via optical fibres and electrical wires to the detection system and power supply. This novel technology will be particularly valuable in applications such as the supervision of skin grafts and ulcer treatments.
58 citations
TL;DR: In this article, the authors proposed new types of stress sensitive and magnetic field tunable microwave composite materials where embedded short ferromagnetic microwire inclusions are used as controllable radiative elements.
Abstract: New types of stress sensitive and magnetic field tunable microwave composite materials are discussed where embedded short ferromagnetic microwire inclusions are used as controllable radiative elements. The dc external magnetic field is applied to the whole composite structure. And, the local stress is transferred to the individual microwires through the accommodating composite matrix. The spatial and angular distributions of microwires can be random, partly ordered, or completely ordered. For a wide frequency range, the free-space microwave response of a wire-filled composite can be characterized by a complex effective permittivity with resonance frequency dispersion. The latter depends on the conductive and magnetic properties of the microwire inclusions that contribute to the ac microwire magnetoimpedance (MI). In the vicinity of the so-called antenna resonance frequency, which is defined by the length of microwires and matrix dielectric constant, any variations in the MI of the microwires will result in large changes of the effective permittivity, and hence the reflection and transmission coefficients for an incident microwave. The field or stress dependence of the effective permittivity arises from the corresponding field or stress sensitivity of the MI in the ferromagnetic microwires with induced circumferential or helical magnetic anisotropy, respectively. The strong field tunable effect in the proposed composite materials can be utilized to introduce reconfigurable microwave properties in coatings, absorbers, and randomizers, and also in new media such as microwave metamaterials and bandgap wire structures. A maximum field tunability of 30 dB was achieved for free-space transmission measurements when the external magnetic field changed from zero to ~40 Oe. The stress sensitivity of reflection and transmission coefficients opens up new possibilities for the distant non-destructive testing and evaluation of composite materials both in the laboratory environment and large scale applications. The stress tunability of transmission coefficient may reach up to 5-8 dB within the elastic limit. The reflection coefficient usually demonstrates less tunability in both cases (field and stress dependent) and may require a multilayer structure to achieve better results, but it is always strong enough for the stress sensing applications.
41 citations
TL;DR: In this article, the Lotus Effect was used to develop technical surfaces for long time application in ships and pipelines, as an air film between surface and liquid leads to drag reduction and thus savings of energy.
Abstract: The majority of organismic surfaces, like the plant cuticle, is not smooth but micro-structured. Moreover, they are often covered with hydrophobic wax crystals, some hundred nm in size. The combination of micro- and nanostructures, together with a hydrophobic chemistry, generates the phenomenon of super-hydrophobicity: Water-droplets on such surfaces exhibit contact angles above 140°. Furthermore, dirt particles can barely adhere and are removed by running water only, hence they are called ‘self-cleaning’. The underlying physico-chemical principles were successfully applied to technical prototypes. This technical conversion was patented and the trade mark Lotus-Effect® was introduced in the mid 1990s. Since then several Lotus-Effect® products like a facade paint, a glass coating or a spray were introduced. Another area of application for which prototypes exist, are textiles for awnings, tents or other outdoor purposes. Recently a different aspect of such surfaces is investigated: structures retaining air under water. Several floating plants and semiaquatic animals show this ability. The aim of this project is to develop technical surfaces for long time application in ships and pipelines, as an air film between surface and liquid leads to drag reduction and thus savings of energy.
40 citations
TL;DR: In this paper, a maneuvering propulsor for an autonomous underwater vehicle (AUV) based on the mechanical design and performance of the sunfish pectoral fin was proposed.
Abstract: The research effort described here is concerned with developing a maneuvering propulsor for an autonomous underwater vehicle (AUV's) based on the mechanical design and performance of sunfish pectoral fin. Bluegill sunfish (Lepomis macrochirus ) are highly maneuverable bony fishes that have been the subject of a number of experimental analyses of locomotor function (5, 6). Although swimming generally involves the coordinated movement of many fin surfaces, the sunfish is capable of propulsion and maneuvering using almost exclusively the pectoral fins. They use pectoral fins exclusively for propulsion at speeds of less than 1.1 body length per second ( BL/s ). The curve in Fig. 1 depicts two peaks of body acceleration of bluegill sunfish during steady forward swimming. These abilities are the direct result of their pectoral fins being highly deformable control surfaces that can create vectored thrust. The motivation here is that by understanding these complex, highly controlled movements and by borrowing appropriately from pectoral fin design, a bio-robotic propulsor can be designed to provide vectored thrust and high levels of control to AUVs. This paper will focus on analyses of bluegill sunfish's pectoral fin hydrodynamics which were carried out to guide the design of a flexible propulsor for AUV's.
38 citations
TL;DR: In this paper, the Wearable Instrument Shirt (WIS) combines a wearable sensor interface with software to map gestures and audio data files to enable real-time interactive musical performances without any need for significant instrument or computer skills.
Abstract: Innovation in textiles and clothing has embodied various combinations of new and existing materials to meet conventional needs of comfort and fashion. Interactive and intelligent textiles are emerging as many new textile materials are being used to form sensors in garments to intimately interact with the human form. Interactive textiles typically contain sensors located within a garment to detect physiological functions that are wirelessly connected to digital infrastructure and application specific software. These devices can be realised in conventional garments and have scope for application in diverse fields including entertainment, education, sport, military and medicine. Position and Motion Sensing devices will be discussed for each application, in terms of the value proposition, performance requirements, regulations, and existing technology. A case study of an entertainment device that uses limb motion to achieve an imaginary instrument, the Wearable Instrument Shirt (WIS) will be discussed in this context. The WIS combines a wearable sensor interface with software to map gestures and audio data files to form an easy-to-use gesture driven instrument that allows real-time interactive musical performances without any need for significant instrument or computer skills.
35 citations
TL;DR: In this article, the authors present an approach to estimate the relative magnitudes of these rate limiting factors, thereby enabling actuator designs to evaluated and optimized for a given application, which is also useful for analyzing rate limits in carbon nanotube actuators and other related technologies.
Abstract: Conducting polymer actuators are of interest in applications where low voltage and high work density are beneficial. These actuators are not particularly fast however, with time constants normally being greater than 1 second. Strain in these actuators is proportional to charge, with the rate of charging being found to limit the speed of actuation. This rate of charging is in turn limited by a number of factors, the dominant factor depending on the actuator and cell geometry, the potential range, the composition and the timescale of interest. Mechanisms that slow response can be as simple as the RC charging time arising from the actuator capacitance and the series resistances of the electrolyte and the contacts, or may involve polymer electronic or ionic conductivities, which can in turn be functions of potential. Diffusion can also be a factor. An approach is presented to help estimate the relative magnitudes of these rate limiting factors, thereby enabling actuator designs to evaluated and optimized for a given application. The general approach discussed is also useful for analyzing rate limits in carbon nanotube actuators and other related technologies.
34 citations
TL;DR: In this article, the authors used dye flow visualization to qualitatively characterize the fluid mechanisms at work during steady-state oscillation of myliobatoid pectoral fin flapping and showed that oscillatory swimming uses fundamentally different fluid mechanisms than undulatory swimming by the generation of leading edge vortices.
Abstract: Myliobatidae is a family of large pelagic rays including cownose, eagle and manta rays. They are extremely efficient swimmers, can cruise at high speeds and can perform turn-on-a-dime maneuvering, making these fishes excellent inspiration for an autonomous underwater vehicle. Myliobatoids have been studied extensively from a biological perspective; however the fluid mechanisms that produce thrust for their large-amplitude oscillatory-style pectoral fin flapping are unknown. An experimental robotic flapping wing has been developed that closely matches the camber and planform shapes of myliobatoids. The wing can produce significant spanwise curvature, phase delays down the span, and oscillating frequencies of up to 1 Hz, capturing the dominant kinematic modes of flapping for myliobatoids. This paper uses dye flow visualization to qualitatively characterize the fluid mechanisms at work during steady-state oscillation. It is shown that oscillatory swimming uses fundamentally different fluid mechanisms than undulatory swimming by the generation of leading-edge vortices. Lessons are distilled from studying the fluid dynamics of myliobatoids that can be applied to the design of biomimetic underwater vehicles using morphing wing technology.
33 citations
TL;DR: In this article, the mechanical, thermal and electrical response of these shape memory wires, at diameters ranging from 25 to 500 mm, under different working conditions, simulating the actual operating condition in real actuators, are examined in depth and discussed, in order to direct the design of the actuator so that the functional properties of the material can be completely exploited.
Abstract: Shape Memory Alloys (SMAs) are active metallic materials classified nowadays as “smart” or “intelligent” materials. One of the main areas of interest is that of actuators. The use of Shape Memory Alloys in actuators offers the opportunity to develop robust, simple and lightweight elements that can represent an alternative to electro-magnetic actuators commonly used in several fields of industrial applications, such as automotive, appliances, etc. The obvious simplicity of mechanical design and minimum number of moved parts is amazing for an actuator. NiTi SMAs demonstrated to have the best combination of properties. Due to its relatively high recovery stress and strain, actuators providing significant force and stroke can be designed. There are perhaps thousands of applications of NiTi-based actuators mentioned in literature and in patents. Successful applications will build on SMA strengths whilst taking into account its weaknesses. SAES Getters S.p.A., thanks to its vertically integrated process and to the scientific and quality approach, developed a NiTi-based wires family which can represent a very good solution for shape memory actuators. The mechanically stabilized SAES Smartflex NiTi actuators show a very sophisticated profile of properties. In this paper the mechanical, thermal and electrical response of these shape memory wires, at diameters ranging from 25 to 500 mm, under different working conditions, simulating the actual operating condition in real actuators, will be examined in depth and discussed, in order to direct the design of the actuator so that the functional properties of the material can be completely exploited. The thermomechanical properties have been investigated and measured by several methods. The most common and useful tests for these commercially available wires will be also described.
TL;DR: In this paper, the authors show that vortex ring formation can be interrupted, but only if the co-flow is sufficiently fast and the vortex ring will stop forming and the remainder of the pulse is ejected as a trailing jet.
Abstract: Pulsed-jets are commonly used for aquatic propulsion, such as squid and jellyfish locomotion. The sudden ejection of a jet with each pulse engenders the formation of a vortex ring through the roll-up of the jet shear layer. If the pulse is too long, the vortex ring will stop forming and the remainder of the pulse is ejected as a trailing jet. Recent results from mechanical pulsedjets have demonstrated that vortex rings lead to thrust augmentation through the acceleration of additional ambient fluid. This benefit is most pronounced for short pulses without trailing jets. Simulating vehicle motion by introducing background co-flow surrounding the jet has shown that vortex ring formation can be interrupted, but only if the co-flow is sufficiently fast. Recent in situ measurements on squid have captured vortical flows similar to those observed in the laboratory, suggesting thrust augmentation may play a role in their swimming performance. Likewise, recent measurements with a mechanical self-propelled pulsed-jet vehicle (“robosquid”) have shown a cruise-speed advantage obtained by pulsing.
TL;DR: In this paper, the application of yarns as electrochemical actuators and as force sensors was studied, and the effect of yarn geometry on actuation and other contributing factors were discussed.
Abstract: Carbon nanotubes have attracted extensive attention in the past few years because of their appealing mechanical and electronic properties. Yarns made through spinning multiwall carbon nanotubes (MWNTs) have been reported. Here we study the application of these yarns as electrochemical actuators, and as force sensors. MWNT yarns are mechanically strong with tensile strengths reaching one GPa. When charge is stored in the yarns they change in length. This is thought to be because of a combination of electrostatic and quantum chemical effects. We report strains up to 0.6 %. The charged yarns can also generate current and change in voltage in response to a change in the applied tension. Electrostatic and quantum effects contributing to actuation are introduced along with the effect of the yarn geometry on actuation and other contributing factors.
TL;DR: In this article, the complete integration of piezoceramic sensor/actuator modules into metal components using high pressure die casting is presented for the fabrication of multifunctional structural elements with enhanced properties.
Abstract: The complete integration of piezoceramic sensor/actuator-modules into metal components using high pressure die casting is a promising approach for the fabrication of multifunctional structural elements with enhanced properties. A technique providing stabilization and protection of the module during the highly dynamic mould filling is presented. Demonstration parts are produced which are fully capable to detect vibrations. An approach to characterize this sensory functionality of the adaptronic system is presented.
TL;DR: In this article, it was shown that a constant voltage loading reduces stiffness, down to zero in some cases, while a constant charge loading increases stiffness, depending on the electrical loading of the dielectric elastomer.
Abstract: Dielectric elastomers, or more precisely dielectric polymers, are a relatively new class of materials for variable-stiffness and variable-damping devices. Dielectric elastomers offer significant potential advantages compared with previous variable stiffness smart materials. Advantages include simplicity, broad dynamic range, ability to reach zero stiffness, low cost, minimal mass, shock tolerance, simple drive circuitry, and design flexibility. Dielectric elastomer devices in the variable-stiffness mode convert electrical and mechanical energy back and forth to change mechanical impedance. This type of electromechanical transduction distinguishes the variable stiffness mode from simply using a dielectric elastomer actuator to alter the geometry, and hence the stiffness, of the device. Stiffness using a variable-stiffness mode depends heavily on the electrical loading of the dielectric elastomer. Analysis shows that a constant voltage loading reduces stiffness, down to zero in some cases, while a constant charge loading increases stiffness. Many applications can be considered for dielectric elastomer variable-stiffness mode such as vibration control, suspensions, and tuning consumer devices for user comfort or preference. As with dielectric elastomer actuators and generators, silicones and acrylics are the most promising materials for variable-stiffness-mode devices.
TL;DR: Structural Health Monitoring (SHM) is an important and growing field in civil engineering as discussed by the authors, where the goal of SHM techniques is to identify, quantify and locate damage in structures.
Abstract: Structural Health Monitoring (SHM) is an important and growing field in civil engineering. The goal of SHM techniques is to identify, quantify and locate damage in structures. In light of the aging infrastructure and recent failures of important bridges, long-term monitoring techniques are being increasing investigated and adopted. In addition to SHM, structural control (SC) is increasingly adopted in modern structures around the world. In the past two decades a number of SC techniques, including, passive, semi-active, and active control methods have been developed and adopted in civil engineering–particularly, in infrastructure such as important tall buildings, critical facilities, and long span bridges. Both SHM and SC technology face significant challenges due to the size and scale of civil engineering structures. In response of these challenges researchers in the U.S.A and around the world have developed new and innovative techniques.This paper summarizes some of the ongoing research in the U.S.A. in the area of monitoring, damage detection and control in civil engineering structures.
TL;DR: Three latent variable methods are implemented in a multivariate statistical analysis scheme for detecting and identifying faults in a multi-sensor network and the results are compared and discussed.
Abstract: In this paper, three latent variable methods are implemented in a multivariate statistical analysis scheme for detecting and identifying faults in a multi-sensor network The proposed methods are applied to a sensor network monitoring a MDOF dynamical system and the results are presented, compared and discussed
TL;DR: The applicability of textile materials and textile processes in the design of antennas to be integrated into the authors' every day clothing or even professional clothing is reported on.
Abstract: Our future garments will not only protect us from the environment or make us look fashionable; they will allow monitoring through an incorporated sensor network. The off-body communication of the sensor data to a nearby base station is therefore preferably operated by a fully integratable and flexible antenna. This paper reports on the applicability of textile materials and textile processes in the design of antennas to be integrated into our every day clothing or even professional clothing.
TL;DR: In this article, the authors examined how a well known problem in reactive ion etching processes, RIE "grass" can be used to great effect to alter surface morphology on the nanoscale for nearly any polymer.
Abstract: Since early this decade, investigations into how geckos achieve their remarkable adhesive properties, have determined that multi-scale compliant systems can allow geckos to attach to nearly any surface through Van der Waals forces. Microscopic hairs on the bottom of gecko feet can make intimate contact over large areas, and allows relatively weak Van der Waals forces to produce significant adhesion on the macroscale. Over the past five years, microfabrication technology has been used to replicate these multi-scale compliant mechanisms, using silicon or polymers to reproduce microscale rods or cantilevers to produce what is known as a dry adhesive. What is more difficult is creating the nanoscale compliant systems that create most contact areas in gecko feet. This work examines how a well known problem in reactive ion etching processes, RIE "grass" can be used to great effect to alter surface morphology on the nanoscale for nearly any polymer. Identical etching parameters in the presence of different elements, like gold or aluminum, can result in radically different surface morphologies and material behaviors, potentially allowing both adhesive and non-adhesive areas to be formed in a single material. This technique is potentially the easiest and fastest way to produce nano-compliant systems for use with dry adhesives.
TL;DR: In this article, a non-volatile, rewritable polymer memory device (PMD) based on active layers containing an admixture of polystyrene, gold nanoparticles and 8-hydroxyquinoline is presented.
Abstract: Organic and polymer based electronic devices are currently the subject of a great deal of scientific investigation and development. This interest can be attributed to the low cost, easy processing steps and simple device structures of organic electronics when compared to conventional silicon and inorganic electronics. In the field of organic electronic memories, non-volatile, rewritable polymer memory devices (PMDs) have shown promise as a future technology where cost and compatibility with flexible substrates are important factors. In this paper PMDs based on active layers containing an admixture of polystyrene, gold nanoparticles and 8-hydroxyquinoline will be presented, showing the devices’ electrical characteristics and memory performance attributes, and where possible discussing possible mechanisms of operation.
TL;DR: In this paper, the potential impact of optical fiber sensors embedded into medical textiles for the continuous monitoring of the patient during Magnetic Resonance Imaging (MRI) is presented, and several pure optical sensing technologies for pulse oximetry and respiratory movements monitoring are reported.
Abstract: The potential impact of optical fibre sensors embedded into medical textiles for the continuous monitoring of the patient during Magnetic Resonance Imaging (MRI) is presented. In that way, we report on several pure optical sensing technologies for pulse oximetry and respiratory movements monitoring. The technique for pulse oximetry measurement is known as NIRS (Near Infra-Red Spectroscopy) in a reflectance mode. In parallel, we tested two different optical sensor based fabric designs breathing activity detection – a macro bending sensor and a fibre Bragg grating sensor consisting in respiratory frequency measurement by intensity variation detection and optical spectral analysis.
TL;DR: In this article, the authors demonstrate progress in Adaptive Impact Absorption (AIA) research field obtained recently in our research group and is based on previously published conference communicates, and present the following applications of AIA concept: Adaptive Landing Gears (ALG) for mitigation of exploitative aircraft loads and adaptive flow control based airbags for emergency landing of the helicopter.
Abstract: This paper demonstrates progress in Adaptive Impact Absorption (AIA) research field obtained recently in our research group and is based on previously published conference communicates. The monograph (Ref.[1]), under preparation, will present soon more detailed discussion of the considered problems. In contrast to the standard passive systems the proposed AIA approach focuses on active adaptation of energy absorbing structures (equipped with sensor system detecting and identifying impact in real time and controllable semi-active dissipaters, so called structural fuses) with high ability of adaptation to extreme overloading. A semi-active or fully-active solutions can be applied, which depend on constant or time-dependent modifications realized via controllable dissipative devices. Feasible, adaptive dissipative devices under considerations can be based on MR fluids or (hydraulic or pneumatic) piezo-valves. The presentation will be devoted to the following applications of AIA concept: Adaptive Landing Gears (ALG) for mitigation of exploitative aircraft loads and adaptive flow control based airbags for emergency landing of the helicopter.
TL;DR: The preparation and charactersiation of novel lipid coated PLGA nanoparticles was investigated and the bioadhesive properties was proofed in a cell culture model.
Abstract: The preparation and charactersiation of novel lipid coated PLGA nanoparticles was investigated in the presented study. The size of the pure nanoparticles could be adjusted in dependence on the stabilizer content. The supported lipid bilayer surrounding the nanoparticles was formed by the liposome spreading technique. The Lipid- coated nanoparticles were characterised using Photon Correlation Spectroscopy (PCS) and atomic force microscopy (AFM) investigations. The bioadhesive properties was proofed in a cell culture model.
TL;DR: In this paper, an ionic liquid is used to ensure the highest ionic conductivity through the IPN matrix, which is necessary in order to achieve the best actuator actuation.
Abstract: Interpenetrating polymer networks (IPNs) have been developed for many years leading to materials with controlled properties. When an electronic conducting polymer (ECP) is incorporated into an IPN, this one becomes a conducting IPN (CIPN). The synthetic pathway ensures a non homogeneous dispersion of the ECP through the IPN thickness of the material. The system is thus similar to a layered one with the advantage that the intimate combination of the three polymers needs no adhesive interface. The last step in making the CIPN into an actuator is to ensure the ionic conductivity by incorporation of an ionic salt. The highest ionic conductivity through the IPN matrix is necessary in order to ensure the best actuation. The chosen salt is an ionic liquid, i.e. 1-ethyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI). Based on IPN architectures electrochemical actuators have been designed and actuation in open air has been characterized.
TL;DR: In the EU- project "STELLA" IST - 028260 the consortium has developed a platform technology of enabling interconnection, packaging and assembling technologies, for example a new generation of stretchable substrates based on non woven with stretchable conductor pattern for large area application.
Abstract: As a consequence of the ambient intelligent vision where the citizen carries along more and more electronic systems near the body wearable electronics is needed. Typical applications are intelligent textiles and clothes, personnel healthcare or fitness monitoring. The electronic systems for these applications have to be stretchable with soft touch nature in order not to hamper the comfort of the user and to be ideally almost non-noticeable to him. They should be reliably withstanding all mechanical and chemical requirements of clothes, in which they are integrated. In the EU- project "STELLA" IST - 028260 the consortium has developed a platform technology of enabling interconnection, packaging and assembling technologies. For example a new generation of stretchable substrates based on non woven with stretchable conductor pattern for large area application has been developed. In order to realize low-cost high volume stretchable electronics printed circuit methods have been modified and applied so far.
TL;DR: In this article, the effects of magnetic field (MF) during the foaming process was analyzed and the results revealed that the magnetic field induced an alignment of Fe particles, and the effect of particles alignment was evident starting from low weight concentrations (5%wt).
Abstract: Polymeric foams with different concentrations of Fe particles were prepared. The effects of magnetic field (MF) during the foaming process was analyzed. Mechanical properties and cell morphology of samples foamed with and without the application of the MF were compared. As revealed by optical and electronic scanning microscopy the magnetic field induced an alignment of Fe particles. The compressive mechanical tests performed on the foams showed an enhancement of the properties with the increase of particles concentration. When the iron particles were aligned by the magnetic field an improvement of the mechanical properties in the alignment direction was measured when compared to the samples with the same particle content. The effect of particles alignment was evident starting from low weight concentrations (5%wt). The mechanical behavior of the samples prepared by using the magnetic field was strongly anisotropic: in the field direction the mechanical behavior was higher than that in the orthogonal direction. The development of cellular structures produced by applying a magnetic field during the foaming process allows the design of anisotropic structures with cell morphology and mechanical properties tailored for desired directions.
TL;DR: In this paper, the fabrication of bar-like magnetostrictive microcantilever (MSMC) in nanoscale was reported and the results ware analyzed and the size effect on the microstructure and properties is discussed.
Abstract: High performance biosensors are urgently needed from medical diagnosis, to food safety/security, to the war on bio-terrorist. Recently, magnetostrictive microcantilever (MSMC) and magnetostrictive particle (MSP) have been developed as high performance biosensor platform. Both MSMC and MSP are wireless sensors and exhibit advantages over current acoustic wave biosensor platforms. Theoretical analysis and experimental results indicate that micro/nano scale MSMC and MSP have ultra-high sensitivities. However, in real detection, there is a challenge faces all micro/nano scale sensors because of their small size. That is, a long time is required for the tiny sensors to react with the target species. Due to the magnetic and wireless nature, MSP provides a unique way to bring the nanosensors to target species. The fabrication of bar-like MSPs in nanoscale is reported. Amorphous Fe-B alloy was selected as target magnetostrictive materials for fabrication. The properties of these nanobars were determined. The morphology and magnetic properties of the nanobars were characterized. The results ware analyzed and the size effect on the microstructure and properties is discussed.
TL;DR: In this article, BaTiO3 ceramics with high density and high dielectric constants were fabricated using a two-step sintering method from hydrothermally synthesized 100 nm BaIO3 nano-particles, and the best specimen with an average grain size of 1.6 μm and a density of 5.91 g/cm3 was obtained.
Abstract: Barium titanate (BaTiO3) ceramics with a high-density were fabricated by two-step sintering method from hydrothermally synthesized 100 nm BaTiO3 nano-particles. The best specimen with an average grain size of 1.6 μm and a density of 5.91 g/cm3 (98.3% of the theoretical value). The dielectric constant was 4500 and electromechanical coupling factor kp was 45%. Large piezoelectric constants d33 = 460 pC/N and d31 = -185 pC/N were observed in the specimens. This was an important practical result towards obtaining a high d33 in non-lead-based BaTiO3 ceramics manufactured by a low-cost process. These results also indicated the possibility of using BaTiO3 ceramics in piezoelectric devices at room temperature. Temperature dependence of dielectric constant showed two peaks located at 24 and 126 oC, corresponding to orthorhombic-to-tetragonal phase transition temperature Tot and Curie temperature Tc, respectively. Owing to the size effect of nanocrystals, Tot shifted to 24 oC. The maximum of electromechanical coupling factor kp appeared close to the phase transition temperature. It also caused a very large temperature coefficient of resonance frequency from room temperature to 60 oC. Hysteresis curve measurement showed a very low coercive field Ec = 115 V/mm. A large Poisson’s ratio, about 0.38, was determined from the ratio of overtone frequency and resonant frequency in the planar mode. The high Poisson’s ratio and the large dielectric constants are most likely the origin of the high piezoelectric constants in the ceramics.
TL;DR: Insects have been in the business of sensory-motor integration for several 100 millions years and can therefore teach us useful tricks for designing agile autonomous vehicles at various scales, including self-guided terrestrial and aerial robots.
Abstract: Equipped with a less-than-one-milligram brain, insects fly autonomously in complex environments without resorting to any Radars, Ladars, Sonars or GPS. The knowledge gained during the last decades on insects' sensory-motor abilities and the neuronal substrates involved provides us with a rich source of inspiration for designing tomorrow's self-guided vehicles and micro-vehicles, which are to cope with unforeseen events on the ground, in the air, under water or in space. Insects have been in the business of sensory-motor integration for several 100 millions years and can therefore teach us useful tricks for designing agile autonomous vehicles at various scales. Constructing a ``biorobot'' first requires exactly formulating the signal processing principles at work in the animal. It gives us, in return, a unique opportunity of checking the soundness and robustness of those principles by bringing them face to face with the real physical world. Here we describe some of the visually-guided terrestrial and aerial robots we have developed on the basis of our biological findings. These robots (Robot Fly, SCANIA, FANIA, OSCAR, OCTAVE and LORA) all react to the optic flow (i.e., the angular speed of the retinal image). Optic flow is sensed onboard the robots by miniature vision sensors called Elementary Motion Detectors (EMDs). The principle of these electro-optical velocity sensors was derived from optical/electrophysiological studies where we recorded the responses of single neurons to optical microstimulation of single photoreceptor cells in a model visual system: the fly's compound eye. Optic flow based sensors rely solely on contrast provided by reflected (or scattered) sunlight froth any kind of celestial bodies in a given spectral range. These nonemissive, powerlean sensors offer potential applications to manned or unmanned aircraft. Applications can also be envisaged to spacecraft, from robotic landers and rovers to asteroid explorers or space station dockers, with interesting prospects as regards reduction in weight and consumption.
TL;DR: The next generation of textiles will have the ability to monitor its environment and interact accordingly in order to accomplish a pre-programmed functionality as discussed by the authors, such textiles can be considered as truly smart textiles, and they would consist of three basic components: sensing and measuring capability; activation capability; and intelligence (programming capability).
Abstract: The current generation of textiles, including technical textiles are passive. However the next generation of textiles will have the ability to monitor its environment and interact accordingly in order to accomplish a pre-programmed functionality. Such textiles can be considered as truly smart textiles, and they would consist of three basic components: 1. sensing and measuring capability; 2. activation capability; 3. intelligence (programming capability).