trix materials consisted of metal and glass 共 soda–lime and phosphate 兲 , and resin. The metals were Fe, Cu, Al, or CeFe 2 . Blended powder was poured into a 6 mm diameter die, pressed at 1 to 3 kN under an inert argon atmosphere, and heated at 10 °C/min to 300–900 °C, depending on the matrix material. The load was removed and the material cooled to ambient temperature while still under the argon atmosphere. Cobalt ferrite was prepared by blending stoichiometric amounts of fine, high-purity cobalt oxide and iron oxide powders in a ball mill, then firing at 1100 °C for 72 hours in flowing dry air to form the compound. The powder was then milled to ⬍ 38 m and blended with chosen ratios of submi- cron metal powders 共 Ag, Ni, Co 兲 . These powder mixtures were cold pressed into shapes and sintered at up to 1450 °C. The resulting samples were typically cylinders 5 mm in di-
Recently, graphene become “raising star” material after its successful production by simple scotch tap approach from easily available graphite in 2004 by Andre Geim and his co-workers . Principally, graphene is made up of single layer sheet of sp 2 bonded carbon atoms with densely packed honeycomb crystal lattice . Its exceptional properties such as high surface area, room temperature Hall effect, tunable band gap, excellent electrical, thermal and conducting properties offered versatile platform to employ it as the active material for the preparation of various composite materials . Recently, numerous efforts were made to review the structure, preparation, properties and applications of graphene and its composite materials [5-8]. Currently, graphene is one of the hottest materials and it can be applied for various energy storage and sensors devices. In this review article, we discussed about the synthesis, properties and applications of the graphene based composite electrode materials.
Technological advancements in the field of semiconductor fabrication process and micro electro-mechanical systems (MEMS) have led to the proliferation of wireless sensors. Wireless sensors continually or intermittently monitor the surrounding environment to gather useful information and transmit that information to a remote base station using radio frequency (RF) transmission for further processing. Because of their small size and wireless communication capability, networks formed by wireless sensor nodes play a significant role in the structural health monitoring of civil infrastructures, aircrafts, process control systems, temperature monitoring in buildings, military surveillance, personal tracking devices, industrial process monitoring, environment and habitat monitoring, healthcare applications, home automation, traffic control, and so on. Such pervasive networks of wireless sensors significantly impact society and create large market opportunities. For these networks to achieve their full potential and autonomy, the source of power supply is an important consideration.
Graphene is a 2D material with superior properties, since it has the advantage of being both conducting and transparent. Due to graphene superior properties, many applications on microelectronics and nanotechnology have been developed to exploit graphene. The objective of this chapter is to review the progress of graphene, the graphene synthesis process and its derivatives in nanomaterial. The structural, optical, electrical and thermal properties of the graphene are also discussed in conjunction with their potential applications, particularly sensors. Graphene-sensor has been developed into many applications and purpose such as gas sensors, biosensor and electrochemical sensors. In addition, this chapter reveals how important graphene is and the potential applications of graphene in the future with its outstanding properties. This chapter aims to offer a basic background of graphene.
Ferrites are engineering materials giving useful magnetic, electrical and structural properties [1-5]. Based on the magnetic properties ferrites are classified as hard and soft. Hard ferrites are those having a high coercivity and high remanence after magnetization. Eg. Permanent ferrite magnet. Soft ferrites are those having a low coercivity. This means the magnetisation of the materials can reverse the direction easily without dissipating much energy. Eg. Transformer, electromagnetic cores. Under soft ferrite there is a type of material called spinel ferrite which crystallizes in spinel structure. The spinel crystal structure is being made up of the closest possible packing of oxygen ions forming f.c.c lattice Metallic cations, magnetic and nonmagnetic; reside on the interstices of the close-packed oxygen lattice. In the spinel structure these cations have either four- or six-fold coordination and form tetrahedra (A) and octahedra (B) sub-lattices that are in themselves arranged in a close- packed arrangement. Spinel ferrite is again classified into three types.
A magnetomechanical model for quantifying the behavior of magnetostrictivematerials as used in Villari-effect sensors has been presented. The model addresses the bidirectional energy transduction between the magnetic and elastic regimes by means of a coupling mechanism posed in terms of a PDE system. This PDE system treats the case of a magnetostrictivematerial driving external loads (actuator mode) or being driven by external loads (sensor mode). Although some model components are ultimately based on phenomenological observation, crucial aspects of the model are constructed from thermodynamic principles. For this reason, it is expected that a near-constant set of parameters will provide accurate characterization of sensor performance over a wide range of regimes, including highly nonlinear regimes where prior models provide inaccurate results.
a low-cost method of producing films with thicknesses in excess of 100 m. The process is based upon a screen print- ing technique that is believed to have been in use for over a thousand years as a form of graphic art reproduction. The processing equipment used in this study is designed for use in the fabrication of electronic circuits and sensors. With thick-film technology, the target film material is mixed with a binder material, often a devitrifying glass frit, and suit- able solvents to produce a printable paste. This paste is then screen printed through a patterned screen onto a suitable substrate, typically alumina, insulated steel or silicon. The printed paste is then allowed to settle prior to drying, which is necessary to remove the solvents within the composition. The final stage of the fabrication process is the firing stage. During this phase, the materials within the film are exposed to temperatures up to 850 ◦ C in a continuous belt furnace. The result is a fired composite thick-film material.
T HE current development and technology for micrometer- sized devices have been facilitated by multidisciplinary areas of research, producing devices based on mechanical, op- tical, electrical, magnetic, and fluidic systems. There have been significant advances in recent years in constructing micrometer scaled devices based on electrical and mechanical systems and there is growing commercial interest. In 1999, devices on the micrometer scale were primarily used for sensing and actuator functions, with the U.S. market value in the $100 million range . The advancement of this technology is being used in many other processes, with the worldwide market thought to exceed $8 billion in the next two years and predicted to increase at a rate of 20% per year, as automotive and telecommunications drive the applications forward. Within the field of microelec- tromechanical systems (MEMS), the incorporation of magnetic materials is presenting a new category of MagMEMS, adding new capabilities and opening up new markets within biomed- ical, astronomy, and information technology , .
Magnetostrictivematerials seem ready to assume an undeniably essential part in applications going from dynamic vibration control, control surface deployment and energy harvesting to stress and torque detecting. Magnetostriction was initially detailed by James Prescott Joule in the mid-1840s. He detected that iron particles changed their dimensional length when their polarization was changed. Next, Villari found that under stress loading condition magnetostrictivematerials changes their polarity, which empowers the utilization of these materials as stress/force sensors. In any case, magnetostrictivematerials were not utilized as actuators or sensors for long time (Atulasimha & Flatau, 2011). Amid World War II, magnetostrictive nickel-based composites of 50 ppm were utilized in building transducers for sonar applications. In the 1960s, it was watched that uncommon earths, for example, terbium (Clark, DeSavage, & Bozorth, 1965) and dysprosium (Mayergoyz & Engdahl, 1999) displayed substantial magnetostriction of ∼ 10000 ppm at low temperatures.
There are two primary failure modes for composites: fibre rupture in tension or fibre buckle in compression , both of which result in an increase stress in the material. Thus the stress state of the composite material is the most important determinant of the structure safety . However, it is difficult to obtain a direct reading of the stress within the material, so a measure of the strain, which is the deformation of a solid due to stress is used instead. There are a number of different sensors being developed for composite damage detection, these include self-sensing in the carbon fibres , glass fibre optical sensors  and piezoelectric sensors . Each method has advantages and disadvantages, i.e. self-sensing in carbon fibres requires no added materials, but is limited to carbon composites, while piezoelectric sensors require the sensors to be attached to the composite surface, but multiple readings can be obtained simultaneously.
substituting the transition metals foriron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferritematerial effective for use as sensors andactuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.
Submarine mapping system identifies and characterize layers of sediment or rock under the seafloor. A transducer emits a sound pulse vertically downwards towards the seafloor, and a receiver records the return of the pulse once it has been reflected off the seafloor . Parts of the sound pulse will penetrate the seafloor and be reflected off of the different sub-bottom layers. The data that is obtained using this system provides information on these sub-floor sediment layers. The sound pulse is often sent from a projector towed behind the ship. The sound travels down to the seafloor. Some of the sound reflects off the seafloor but some of the sound penetrates the seafloor. The ship also tows a number of hydrophones, which detects the reflected sound signal when it reaches the surface. The time it takes the sound to return to the ship can be used to find the thickness of the layers in the seafloor and their position. As shown in Fig.1, this application requires giant materials for high power generation
In recent years the application of magnetic materials increases as per the high frequency requirement. Lithium Ferrite is one of the most versatile magnetic materials which are generally useful for microwave devices, such as isolators, circulators, gyrators and phase shifters. Different types of polycrystalline ferrites have their specific advantages as Li substituted ferrites has high dielectric constant, low sintering temperature etc. than other substituted ferrites. Some novel characteristics of polycrystalline ferrite over normal dielectric Abstract: In this communication era the extensive use of ferrites open the different angle of research in the field of magnetic materials especially in ferritematerials. Li-Ferrites are the most versatile magnetic materials used for the high frequency microwave systems. The substituted lithium ferrites have been found most suitable for microwave device applications because of their inherent properties such as high Curie temperatures, high dielectric constant, high saturation magnetization & low dielectric losses. A composition of titanium substituted Li-ferrite with saturation magnetization 2200 Gauss has been synthesized and investigated for antenna applications in microwave frequency range. The material was prepared by solid state reaction technique (SSRT) and later studied for its electrical, magnetic & structural behaviors. It is observed that LiTiMg ferrite shows different magnetic behavior during DC biasing for microwave frequency antenna applications. The paper describes a precise description of LiTiMg-ferrite preparation, its characteristic plots and its potentials for microwave antenna application with a detailed study of nonreciprocal behavior of LiTiMg ferrite slab or substrate under magnetic biasing.
Near room temperature, these devices offer the greatest sensitivity to temperature differences – an order of magnitude greater than PTCs or thermocouples. The nominal resistance of the NTC thermistors used in McLaren Electronics sensors is 5kohm at 25°C. However, the resistance decreases very rapidly with temperature, making them less suitable for accurate high temperature measurements. Furthermore, the low resistance at higher temperatures makes the sensors sensitive to the resistance of the harness and connector contacts.
diffusional flux of hydrogen peroxide or oxygen to the elec- trode surface, is probably the technique used most often for glucose biosensors. On the other hand, the enzymatic reac- tion causes pH changes due to the production of gluconic acid. In particular, an increase of the glucose concentration causes a lowering in pH value (Jung et al., 2000). Hence, a GluOx-loaded pH-sensitive hydrogel changes its swelling state dependent on the surrounding glucose concentration. As shown in Ishihara et al. (1984) large swelling changes are possible; they used gels based on copolymers of hydrox- ypropyl methacrylate (HPMA) and N,N-diethyl-aminoethyl methacrylate (DEAMA) containing GluOx. Changes in glu- cose concentrations resulted in changes of the pH value within the hydrogel due to the GluOx-catalyzed production of gluconic acid. The gluconic acid protonated the tertiary amine groups of the DEAMA in the gel and produced a charged hydrogel network. Electrostatic repulsive forces be- tween the amino groups increased swelling of the hydrogel. The corresponding swelling degree (SG) of the hydrogel can be detected as a mass change by means of the weighing of the free swollen hydrogel samples, or as a volume change by using a microscope and a charge-coupled device (CCD) camera.
The peptide conformation change with pH was also applied in material synthesis where the domain size and the crystalline structure of semiconductors on substrates can be controlled since the charge and hydrophobic distribution on surfaces is sensitively tuned by the peptide conformation via the actuation process (Fig. 1). 42 However, in nature, this function is already developed with more complexity such as camouﬂaging. For example, cephalopods, Hawaiian bobtail squid, can manipulate the color of skin by the external stimulus of photon. 81 The photonic structure of the skin consists of multilayer stacks of refractive tissues, reﬂectin that function as diﬀraction grading (Fig. 11(a) and (b)). 82,83 This squid alternates the refractive index dielectrics of skin by changing the spacing between high refractive index platelets or the thickness of the platelets, which ultimately change the light interference to control the absorption and the reﬂection. The hurdle for the application of these reﬂectin proteins to biomimetic devices is to process them into ﬁlms, which are insoluble in most organic solvents. This barrier was overcome by using an ionic liquid solvent to cast thin ﬁlms with a ﬂow-coating technique. 84 Recently, this function was further developed to simpler biopolymer-based responsive photonic crystals and full color pixels (Fig. 11(c)). 85,86 In this system, the hydrophilic layer of block-copolymers swells by the contact with water and the spacing of glassy hydrophobic layers change the index of
Today chemical sensors are widely used either singly to detect a specific chemical or collectively in arrays to sense or analyse complex mixtures of chemicals. A wide variety of materials including polymers, ferroelectric ceramics, piezoelectric semiconductors and shape memory films have been studied and used to manufacture an assortment of chemical sensors [1- 3]. These sensors have been used in a wide variety of applications such as gas detection, food processing, cosmetics and pharmaceuticals [4-8]. In recent years, textiles have also been considered as a possible avenue for developing personal sensing and monitoring systems for medical, health & safety and military applications [9-11]. Historically, various forms of textile materials have been universally worn by humanity for thousands of years. Accordingly, over time, changing requirements and fashions, individuals have readily changed their clothing styles to meet the challenges of the day. Thus, textiles are easily available, widely used and offer a unique platform that can be incorporated into the design of wearable sensors and personal monitoring systems. Currently, wearable sensors have been used in a variety of healthcare monitoring and diagnostic applications. In particular, physiological monitoring can significantly contribute to diagnosis, promote ongoing treatment and assist in patient rehabilitation
of Nottingham with ﬁbers reclaimed at RCFL) was performed at Imperial College London ; microstructure, mechanical properties, and failure and toughening mechanisms were investigated, and the inﬂuence of recycling and re-manufacturing processes analyzed. The study showed that the extensive breakage of ﬁbers during re- manufacturing led to a considerable degradation of tensile strength at the composite level; in addition, it was found that ﬁber bundles, held together by minimal amounts of residual matrix not completely pyrolysed, increase the in-plane fracture toughness of the material. The work by Pimenta et al.  proved that a feature usually seen as a recycling defect (incomplete removal of matrix) can actually enhance the mechanical response of the recyclates, which illustrates the need for a comprehensive approach towards the optimization of processes. In addition, the experimental observations were used to develop multiscale analytical models to predict the properties of recycled composites, which can be used in the design of rCFRP structural components.