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This paper describes a laterally deflecting micromachined device that offers high sensitivity and wide dynamic range to electronically monitor the thermal expansion coefficient, tensile and compressive residual strain and Young's modulus of microstructural materials, as well as the temperature dependence of these properties. The device uses sidewal...
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... Carbon nanotubes (CNTs) are the stiffest known material and buckle elastically (or fracture) under large bending or compressive load [113]. It has high tensile strength and elastic modulus of 100 GPa and 1.27 TPa [114], respectively; thermal conductivity of 2000 W/mK [115]; current density of 1015 A/m 2 and conductance of 13 kΩ −1 [116]. Besides their good mechanical and thermal properties, CNTs have large surface-to-volume ratios, high biocompatibility, and excellent optical properties. ...
Research shows that monolithic Al alloy has very attractive properties required in the production of aerospace, automotive, electrical and electronic, sports and recreational components/equipment. However, its low strength and low wear resistance have challenged its applications in some other critical industrial utilities. Nonetheless, the invention of metal composites has removed such barriers. The addition of one or more reinforcements to Al has helped in the creation of aluminium matrix composites (AMCs), which has not only increased the global utilization of Al alloy, but has been a major source of global revenue and job. This review was, therefore, aimed at studying recent works on AMCs with the aim of ascertaining the recent innovations in the development of advanced Al composites, which can replace steel components in most industrial applications at a cheaper rate. It was observed from the study that AMCs can be developed via solid and liquid fabrication techniques. Powder metallurgy was reported as the most effective method of producing hybrid Al nanocomposites, with spark plasma sintering as the best technique. In the liquid process, stir casting was reported as the most cost effective, but was challenged by agglomeration. It was recommended that agglomeration be ameliorated by cryogenic ball milling and an in situ fabrication technique. It was also recommended that more cost effective agro-waste nanoparticles should be developed to replace more costly conventional reinforcements. In summary, it was recommended that more research on the exploration of Al alloy at a cheaper rate should be carried out.
... It is a sensing technology based on the capacitive coupling that takes the human body's capacitance as the input [13]. It allows reliable solution for applications such as measuring liquid levels [14], material properties [15], human-to-machine interface [16] and also to measure different types of physical signals like humidity [17], respiration [18,19], acceleration [20], pressure [21], position [22] etc. ...
Smart textile has opened a new paradigm of application. Therefore, interest in developing a textile-based sensor system to interact with a machine has been elevated significantly. Touch and pressure are vital interests for multipurpose use, leading to the prior work on developing textile-based sensors using embroidery, multi-layer weaving, and different printing processes. The complexity of those works requires an additional setup and machines for the application. This paper presents a novel approach to developing a low-cost and scalable tactile sensor to sense touch and conjugated pressure exerted over the fabric by means of capacitance variation using commercial stainless-steel thread and low-cost lockstitch sewing machine. The research focused on determining the distinct possibility of sensing the touch stimuli and finger pressure as the capacitance range variation and finding out the allusive structural variables of interdigitated capacitor (IDC) and parallel plate capacitor (PPC) of the sensor. For IDC, the mean capacitance variation found 1.28 pF/gm, whereas 0.81pF/gm found for the PPC structure. For both cases, 11.3 gm measured as the least possible sensing pressure. The repetitive percentage (%) of the sensor (IDC) found 97.91 after testing 1016 consecutive finger pressings cycles. The research demonstrated a circuit where the capacitance range was segmented into five slots assigning individual LEDs to sense the different ranges of touch and pressure. The capacitance range (<20pF–600pF<) facilitates the sensor to use in touch-sensitive multimodal switching and physiological monitoring where tactile information can create smart textile system intelligence.
... Operated NEMs switches and accessible memory devices have also been envisioned in nearby future. Powerful control and deterministic mode of synthesis of CNT will further explore exciting opportunities and greater possibilities of finding novel nanomaterials and other devices [38]. ...
... Strains can be measured by sensors that rely on the piezoresistive effect , the frequency shift of a resonator's fundamental mode [34][35][36], the piezoelectric effect [37,38], the capacitance change [39][40][41][42][43], the optical properties changes [44][45][46][47][48][49], and other effects [50][51][52]. Piezoresistive effects consist of changes in the electrical resistance of a material when subjected to a mechanical strain. ...
Carbon nanotube yarns are micron-scale fibers comprised by tens of thousands of carbon nanotubes in their cross section and exhibiting piezoresistive characteristics that can be tapped to sense strain. This paper presents the details of novel foil strain gauge sensor configurations comprising carbon nanotube yarn as the piezoresistive sensing element. The foil strain gauge sensors are designed using the results of parametric studies that maximize the sensitivity of the sensors to mechanical loading. The fabrication details of the strain gauge sensors that exhibit the highest sensitivity, based on the modeling results, are described including the materials and procedures used in the first prototypes. Details of the calibration of the foil strain gauge sensors are also provided and discussed in the context of their electromechanical characterization when bonded to metallic specimens. This characterization included studying their response under monotonic and cyclic mechanical loading. It was shown that these foil strain gauge sensors comprising carbon nanotube yarn are sensitive enough to capture strain and can replicate the loading and unloading cycles. It was also observed that the loading rate affects their piezoresistive response and that the gauge factors were all above one order of magnitude higher than those of typical metallic foil strain gauges. Based on these calibration results on the initial sensor configurations, new foil strain gauge configurations will be designed and fabricated, to increase the strain gauge factors even more.
... As a result, the device is bent. Based on the bending curvature and the mechanical properties of PDMS (i.e., Young's modulus, etc.), the applied pressure on the device can be calculated [9]. Meanwhile, under the pressure, the shape of nanopores and the interspace among the nanopores are changed, as a result, the reflected optical signals from the nanopore thin film (i.e. ...
... They are the backbone of many MEMS devices, Younis [1]. The combination of the electrostatic actuation and microbeam structure has many applications in industrial and scientific fields like mass sensing systems, micro pressure sensors, micro flexible joints and ink injection printers as presented by Seoka [2], Kamisuki [3], Chu et al. [4], Hassanpour et al. [5], Takashi et al. [6] and Chau et al. [7], Gangi et al. [8]. ...
In this paper, the problems of state estimation, tracking control and shape control in a micro-cantilever beam with nonlinear electrostatic actuation are investigated. The system's partial differential equation of motion is converted into a set of ordinary differential equations by projection method. Observabillity of the system is proven and a state estimation system is designed using extended Kalman filter (EKF) algorithm. A tracking control system is designed to make a specific point of the beam follow a reference signal. The effect of mode selection to include in model on controller performance is also investigated. Based on the tracking controller a shape control algorithm is designed to form the shape of beam into a desired shape. The proposed algorithms are validated by numerical simulation and resulted in a promising performance.
... In addition to optical and acoustical strain sensors, other physical quantities like resistance [11,12], capacitance [13,14], inductance [15], and magnetic field [16] are also used to measure strains. Among these options resistive strain sensors are widely used because of their simple detection mechanism. ...
This study uses the Joule heating effect-generated temperature difference to monitor in real-time and localize both compressive and tensile strains for the polymer substrates used in the roll-to-roll process. A serpentine gold (Au) line was patterned on a polyethylenenaphthalate (PEN) substrate to form the strain sensor based on thermoresistive behavior. This strain sensor was then subjected to either current or voltage to induce the Joule heating effect on the Au resistor. An infrared (IR) detector was used to monitor the strain-induced temperature difference on the Au and PEN surfaces and the minimal detectable bending radius was 0.9 mm with a gauge factor (GF) of 1.46. The proposed design eliminates the judgment ambiguity from conventional resistive strain sensors where resistance is the only physical quantity monitored. This study precisely and successfully indicated the local strain quantitatively and qualitatively with complete simulations and measurements.
... The proposed approach is an array of V-shaped bent-beam structures [2]. Similar structures have been previously proposed in the literature mainly as in-plane thermal actuators [3] or strain sensors [4]. Here, the remote sensing of environment temperature is addressed. ...
Contactless passive sensors that can be interrogated with a remote strategy raise interesting applications in different fields. A powering solution based on "classical" wiring can therefore harm the device or significantly affects its performances. At the same time, it is extremely important that the contactless sensor doesn't require batteries or power supplies inside the harsh environment (in order to decrease the space occupied, avoid explosions or critical operative conditions). The sensor node composed of a contactless passive element, a conditioning unit and a communication system (e.g. wires, bus, RF), can be represented by an autonomous and self-powered system through the adoption of an energy harvester. The aim of this work is to present a review on integrated passive sensor to measure temperature inside harsh areas exploiting integrated solutions for the self-powering conditioning unit through an energy harvester.
... One of the most recurrent actuating and sensing methods in MEMS systems is based on electrostatic force because of its high e ciency and simple structure and manufacturing. The combination of the electrostatic actuation and micro-beam structure has many applications in industrial and scienti c elds like mass sensing systems, micro pressure sensors, micro exible joints, micro rate gyros and ink injection printers [4][5][6]. ...
A closed-loop control methodology is investigated for stabilization of a vibrating non-classical micro-scale Euler-Bernoulli beam with nonlinear electrostatic actuation. The dimensionless form of governing nonlinear Partial Differential Equation (PDE) of the system is introduced. The Galerkin projection method is used to reduce the PDE of system to a set of nonlinear Ordinary Differential Equations (ODE). In non-classical micro-beams, the constitutive equations are obtained based on the non-classical continuum mechanics. In this work, proper control laws are constructed to stabilize the free vibration of non-classical micro-beams whose governing PDE is derived based on the modified strain gradient theory as one of the most inclusive non-classical continuum theories. Numerical simulations are provided to illustrate the effectiveness and performance of the designed control scheme. Also, the results have been compared with those obtained by the classical model of micro-beam.
... Chu et al. [51] proposent une structure de capteur différentiel de déformation à effet capacitif, pour diminuer l'influence d'effets parasites. Son objectif est de détecter la déformation résiduelle, mais le montage s'adapte bien à mesurer tous les genres de déformation. ...
... . I-35 Capteur différentiel de déformation[51] ...
The objective of this assertation is to develop an instrumented cylinder in order to measure its deflection status in medical applications. The cylinders are made of two types of materials: stainless steel and NiTi. The microgauges are distributed along the cylinder to measure its real-time surface strain, thus allowing the cylinder to be guided to its planned destination during a surgical operation.Several approaches for strain measurement are presented and compared, and strain measurement with semiconductor piezoresistive microgauges integrated on the cylinder appears to be the optimal method considering the sensitivity, biomedical compatibility and feasibility in microfabrication.Theoretical analysis and finite element method analysis are carried out in order to analyze the mechanical behavior of the deflected cylinder and to determine the optimal position and size of the piezoresistive microgauges on the cylinder. A first prototype was developed and characterized to verify the functionality of our system.The microgauges are implemented on thin cylinders by microfabrication in cleanroom. Germanium is used as the piezoresistive material. Due to the curved geometry of metal cylinders as the substrate for microfabrication, several ajustments are made to the standard process of material deposition and surface machining. The analysis of experimental results, as well as the possible upgrades of the current process, are discussed.
