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This paper puts forward a new method to measure the force characteristics of the buttress’ ship–pipe connection. First, the positions of stress sensors are determined by the numerical model, and th...

Sensors are becoming increasingly significant in our daily life because of the rapid development in electronic and information technologies, including Internet of Things, wearable electronics, home automation, intelligent industry, etc. There is no doubt that their performances are primarily determined by the sensing materials. Among all potential candidates, layered nanomaterials with two-dimensional (2D) planar structure have numerous superior properties to their bulk counterparts which are suitable for building various high-performance sensors. As an emerging 2D material, MXenes possess several advantageous features of adjustable surface properties, tunable bandgap, and excellent mechanical strength, making them attractive in various applications. Herein, we particularly focus on the recent research progress in MXene-based sensors, discuss the merits of MXenes and their derivatives as sensing materials for collecting various signals, and try to elucidate the design principles and working mechanisms of the corresponding MXene-based sensors, including strain/stress sensors, gas sensors, electrochemical sensors, optical sensors, and humidity sensors. In the end, we analyze the main challenges and future outlook of MXene-based materials in sensor applications.

Optical techniques for recording and manipulating cellular electrophysiology have advanced rapidly in just a few decades. These developments allow for the analysis of cardiac cellular dynamics at multiple scales while largely overcoming the drawbacks associated with the use of electrodes. The recent advent of optogenetics opens up new possibilities for regional and tissue-level electrophysiological control and hold promise for future novel clinical applications. This article, which emerged from the international NOTICE workshop in 20181, reviews the state-of-the-art optical techniques used for cardiac electrophysiological research and the underlying biophysics. The design and performance of optical reporters and optogenetic actuators are reviewed along with limitations of current probes. The physics of light interaction with cardiac tissue is detailed and associated challenges with the use of optical sensors and actuators are presented. Case studies include the use of fluorescence recovery after photobleaching and super-resolution microscopy to explore the micro-structure of cardiac cells and a review of two photon and light sheet technologies applied to cardiac tissue. The emergence of cardiac optogenetics is reviewed and the current work exploring the potential clinical use of optogenetics is also described. Approaches which combine optogenetic manipulation and optical voltage measurement are discussed, in terms of platforms that allow real-time manipulation of whole heart electrophysiology in open and closed-loop systems to study optimal ways to terminate spiral arrhythmias. The design and operation of optics-based approaches that allow high-throughput cardiac electrophysiological assays is presented. Finally, emerging techniques of photo-acoustic imaging and stress sensors are described along with strategies for future development and establishment of these techniques in mainstream electrophysiological research.

A nervous sweat may seem like an inconvenience, but your body could be releasing important signals. Herein, Gao and colleagues develop a wearable sensor with integrated microfluidics, immunoassays, and electronics for tracking cortisol in sweat—as a biomarker of stress.

Many historical cities enjoy the presence of masonry buildings with inestimable historical, artistic and cultural value. Old masonry buildings often suffer structural deficiencies, design faults and materials aging process. In recent years, many researchers focused their attention on the opportunities that structural health monitoring (SHM) can ensure for the health state of existing masonry structures, where damage can be difficult to be promptly predicted, pontentially causing abrupt collapses, with high risks for the community. This paper presents an experimental study on the effectiveness of two types of stress sensor for SHM of new masonry elements. Ceramic piezoelectric sensors and capacitive sensors were installed in mortar joints of two series of specimens made of calcarenite stone masonry and clay brick masonry. All specimens were tested under uniaxial compression with displacement control, to assess the effectiveness of sensors in recording pressure variation within the different types of masonry and therefore testing their potential use for SHM applications. Even though both the ceramic and capacitive sensors were designed as stress sensors for concrete structures, their installation within mortar joints provided a good response, based on the comparison with standard measurement devices. Results demonstrate the suitability of the sensors even for SHM of masonry structures.

The emergence of new applications, such as in artificial intelligence, the internet of things, and biotechnology, has driven the evolution of stress sensing technology. For these emerging applications, stretchability, remoteness, stress distribution, a multimodal nature, and biocompatibility are important performance characteristics of stress sensors. Mechanoluminescence (ML)-based stress sensing has attracted widespread attention because of its characteristics of remoteness and having a distributed response to mechanical stimuli as well as its great potential for stretchability, biocompatibility, and self-powering. In the past few decades, great progress has been made in the discovery of ML materials, analysis of mechanisms, design of devices, and exploration of applications. One can find that with this progress, the focus of ML research has shifted from the phenomenon in the earliest stage to materials and recently toward devices. At the present stage, while showing great prospects for advanced stress sensing applications, ML-based sensing still faces major challenges in material optimization, device design, and system integration.

INTRODUCTION AND OBJECTIVE:Adenosine monophosphate-activated protein kinase alpha 2 (AMPK-α2) is a subunit of AMPK with catalytic kinase domain that senses cellular energy deprivation and signals c...

A study on the design, simulation and characterization of a reconfigurable terahertz (THz) filter, composed of two frequency-selective surfaces (FSSs) with applications on sensor devices in general and highly sensitive stress sensors, is presented in this paper. Using the developed theoretical model, we found out that by careful tuning the wire parameters, it is possible to control the filter sensitivity and also the energy transmission and reflection that passes through the structure. Numerical modelling of both the mechanical and electromagnetic components (using the elasticity equation and Maxwell&rsquo, s equations, respectively) has been undertaken for two types of the device assemblies based on different thermoplastic polymers transparent to the THz radiation, namely: high-density polyethylene (HDPE) and polytetrafluoroethylene (PTFE), operating in a THz window from 395 to 455 GHz. The numerical results allowed us to characterize the relation between the reflectance/transmittance and the amount of force required to obtain a specific frequency shift along that window. It was found that the device assembled with HDPE presents a more linear response and it is able to pass from a full transparency to almost full opacity using only its linear operating zone. Due to its characteristics, this THz filter might be an interesting solution not only for THz sensors based on reconfigurable filters but also for optical modulators for the THz domain.

Plants, due to their sessile nature, face several environmental adversities. Abiotic stresses such as heat, cold, drought, heavy metals, and salinity are serious threats to plant production and yield. To cope with these stresses, plants have developed sophisticated mechanisms to avoid or resist stress conditions. A proper response to abiotic stress depends primarily on how plants perceive the stress signal, which in turn leads to initiation of signaling cascades and induction of resistance genes. New biotechnological tools such as RNA-seq and CRISPR-cas9 are quite useful in identifying target genes on a global scale, manipulating these genes to achieve tolerance, and helping breeders to develop stress-tolerant cultivars. In this review, we will briefly discuss the adverse effects of key abiotic stresses such as cold, heat, drought, and salinity. We will also discuss how plants sense various stresses and the importance of biotechnological tools in the development of stress-tolerant cultivars.

As the electronics in our daily lives proliferate, they continue to be largely limited to rigid form factors with bulky packaging dictated by traditional electronics manufacturing processes and fragile components. Yet for applications ranging from wireless, low-profile medical devices to smart food labels to aircraft with embedded stress sensors, there's a need for high-performance electronics that conform to the shape of our bodies, vehicles, and consumer goods. Flexible Hybrid Electronics (FHE), which combine additive manufacturing processes with flexible silicon will enable these capabilities. To move these concepts from the lab to the manufacturing floor in the United States, the Department of Defense established NextFlex, America's Flexible Hybrid Electronics Manufacturing Institute in 2015. Based in San Jose, CA, NextFlex is a $170M public-private partnership that is building a domestic FHE manufacturing ecosystem by developing manufacturing processes and tools with its member companies and universities, standing up an FHE manufacturing pilot line in Silicon Valley, and establishing education and workforce development programs to train tomorrow's workforce. This presentation will focus on the FHE opportunity, the NextFlex FHE manufacturing roadmaps, and NextFlex projects in areas such as device integration & packaging, modeling & design tools, and printed flexible components.

In previous chapters, we discussed the material preparation for the piezotronic strain/stress sensors. This chapter focuses on the sensing mechanism. Different types of strain/stress sensors have been invented for not only conventional applications but also emerging fields like artificial skin [114] and human-machine interface [115]. In spite of the large number of designs, the fundamental mechanisms enabling those sensors fall into only a few categories. One major category is based on the phenomenon that a mechanical strain can affect the charge carrier transport in a homogeneous material with two electrodes. Altering of the transport characteristics can come from the geometric change, the piezoresistive effect that is related to the material resistivity [116], and the piezotronic effect that is related to the interfacial barrier between the material and the electrode [10, 17].

This paper presents a solution for on-chip temperature and mechanical stress measurement in CMOS integrated circuits. Thereby both temperature and stress sensors are realized as resistive Wheatstone bridges. By design, both sensors show outputs affected by non-linearities and parasitic cross-sensitivities. The novelty presented in this work is to combine both non-ideal sensor outputs by applying a two-dimensional Newton-Raphson method to extract the actual values of temperature and mechanical stress which were obtained with errors of less than 0.5 K and 0.5 MPa.

Stress is a major problem in our society today and poses major concerns for the future. It is important to gain an objective understanding of how average individuals respond to events they observe in typical environments they encounter. We developed a computational model of stress based on objective human responses collected from human observers of environments. In the process, we investigated whether a computational model can be developed to recognize observer stress in abstract virtual environments text, virtual environments films and real environments real-life settings using physiological and physical response sensor signals. Our work proposes an architecture for a computational observer stress model. The architecture was used it to implement models for the different types of environments. Sensors appropriate to the different types of environment were investigated where the aims were to achieve unobtrusive methods for stress response signal collection, reduce encumbrance and hence, enhance methods to capture natural observer behaviors and produce stress models that recognized stress more robustly. We discuss the motivations for each investigation and detail the experiments we conducted to collect stress data sets for observers of the different types of environments. We describe individual-independent artificial neural network and support vector machine based model classifiers that were developed to recognize stress patterns from observer response signals. The classifiers were extended to include a genetic algorithm which was used to select features that were better for stress recognition and reduce the use of redundant features. The outcomes of this research provide a possible future extension on managing stress objectively.

In this work, piezoresistive stress sensors test circuit fabricated into the sensitive structure as part of the normal processing procedure is used to measure the stresses difference distribution before and after the assembly. Sensor resistances were recorded before and after the adhesive bonding. Using the theoretical equations, the stresses on the die surface have been calculated from the data of sensor resistances. This technology not only provides a performance diagnostic tool for the sensitive structures and the miniature components, but also presents a design tool for low-stress micro-assemblies of miniature components.

Stress is a major health problem in our world today. For this reason, it is important to gain an objective understanding of how average individuals respond to real-life events they observe in environments they encounter. Our aim is to estimate an objective stress signal for an observer of a real-world environment stimulated by meditation. A computational stress signal predictor system is proposed which was developed based on a support vector machine, genetic algorithm and an artificial neural network to predict the stress signal from a real-world data set. The data set comprised of physiological and physical sensor response signals for stress over the time of the meditation activity. A support vector machine based individual-independent classification model was developed to determine the overall shape of the stress signal and results suggested that it matched the curves formed by a linear function, a symmetric saturating linear function and a hyperbolic tangent function. Using this information of the shape of the stress signal, an artificial neural network based stress signal predictor was developed. Compared to the curves formed from a linear function, symmetric saturating linear function and hyperbolic tangent function, the stress signal produced by the stress signal predictor for the observers was the most similar to the curve formed by a hyperbolic tangent function with p

Recently, a novel stress sensor, which utilizes the elasto-magnetic (EM) effect of ferromagnetic materials, has been developed to measure stress in steel cables and wires. In this study, the effectiveness of this EM based stress sensors for monitoring of the cable tension force of a real scale cable-stayed bridge was investigated. Two EM stress sensors were installed on two selected multi-strand cables in Hwa-Myung Bridge, Busan, South Korea. Conventional lift-off test was conducted to obtain reference cable tension forces of two test cables. The reference forces were used to calibrate and validate cable tension force measurements from the EM sensors. Tension force variations of two test cables during the second tensioning work on Hwa-Myung Bridge were monitored using the EM sensors. Numerical simulations were conducted to compare and verify the monitoring results. Based on the results, the effectiveness of EM sensors for accurate field monitoring of the cable tension force of cable-stayed bridge is discussed.

A technical challenge in fabrication of ultra-thin sensor chip (UTSC) is to keep chip integrity in debonding the ultra-thin chips from grinding facilities. This paper presents a new debonding method by utilizing a thermally decomposable polypropylene carbonate (PPC), as the temporary bonding adhesive. Because PPC can readily decompose at relatively low temperature, this method can maintain the chip integrity even the chips have a thickness of tens of microns. UTSCs with thickness of 30μm have been achieved using this method, and stress sensors have been developed to verify the performance of UTSC. The experimental results show that the proposed method is able to fabricate UTSC with good flexibility and characterizations, demonstrating the newly proposed method an enabling technology for fabrication of sensors for flexible and wearable applications.

In this paper, we design, fabricate, and evaluate octagonal nMOSFET multi operation device for normal MOSFET operation, detection of 8 stress direction, and variation of temperatures. In previous works, one sensor device can detect only one physical or chemical phenomenon. If we get some sensing data, such as temperature, stress, and etc., more than two sensor devices must be implemented. According to stress detection, stress sensors reattach along stress direction for measurement, because most of the previous stress sensors can sense only one dimension. However, octagonal MOSFET is not necessary to adjust because this device has radial eight direction output terminals and can accommodate various sensing using these terminals. Furthermore, this device can also measure the variation of threshold voltage using these output terminals. For example, proposed device can get variety of temperatures due to the temperature characteristics of threshold voltage. As the results, we can realize that it can sense 8 stress directions and a variety of temperature.

The structural health monitoring of large-scaled fiber-reinforced composite components plays a crucial role for the further advancement of lightweight design approaches for a large-range application spectrum. Using textile-based and technological integrated stress sensors within the composite’s textile reinforcement, the detection of serious structural damages on early stages as well as an in-situ monitoring of mechanical loading conditions in inaccessible areas within immediate distance of the load-bearing layers of the subsequent composite component can be realized by those in situ condition monitoring systems, enabling the possibility of just in time maintenance or even local repairs before full structural failures occur.

In this study, the parameters (i.e., contact stress at the die-sheet interface and the punch velocity) were measured by the installation of film stress sensors in the fine-blanking die. A regression model was established to investigate the degree of importance of the parameters and their interaction on reducing the crack ratio of fine-blanked surface. Analysis of variance (ANOVA) was then performed to check the adequacy of the regression model. The optimal results of the regression model agreed well with the experimental result. The regression analysis indicated that the contact stress have a major influence, followed by the interaction and the punch velocity. The importance of the interaction means that the ability of contact stress in crack ratio reduction depends on the level of punch velocity. The result could be useful to facilitate an improvement in the quality of the fine-blanked parts by the optimization parameters.

In this paper, the application of magnetoelasticity in static tension monitoring for large steel cables is discussed. Magnetoelastic (EM) stress sensors make contact-free tension monitoring possible for hanger cables and post-tensioned cables on suspension and cable-stayed bridges. By quantifying the correlation of magnetic relative permeability with tension and temperature, the EM sensors inspect the load levels in the steel cables. Cable tension monitoring on Qiangjiang (QJ) 4th Bridge demonstrates the reliability of the EM sensors.

Experiments with instrumented displacement piles have shown that the ultimate shaft friction that can develop in a given sand horizon decreases as the pile tip penetrates to deeper levels. This phenomenon, which is now commonly referred to as friction fatigue, is investigated here using centrifuge model piles equipped with lateral stress sensors, and by drawing on other experimental data from the laboratory and the field. It is shown that the primary mechanism controlling friction fatigue is the cyclic history imparted during pile installation to soil elements at the pile–sand interface. For a given installation method the stationary lateral stress acting at any given level on a displacement pile can be described as a relatively unique function of the cone penetration test end resistance and the number of cycles imposed during installation. The strong influence of cycling, which is also seen in cyclic constant normal stiffness interface shear tests, is attributed to contraction of a narrow shear zone at t...

Under the proper orientations and excitations, the transverse output of rotationally symmetric four-contact van der Pauw (VDP) stress sensors depends upon only the in-plane shear stress or the difference of the in-plane normal stresses on (100) silicon. In bridge-mode, each sensor requires only one four-wire measurement and produces an output voltage with a sensitivity that is 3.16 times that of the equivalent resistor rosettes or bridges, just as in the normal VDP sensor mode that requires two separate measurements. Both numerical and experimental results are presented to validate the conjectured behavior of the sensor. Similar results apply to sensors on (111) silicon. The output voltage results provide a simple mathematical expression for the offset voltage in Hall effect devices or the response of pseudo Hall-effect sensors. Bridge operation facilitates use of the VDP structure in embedded stress sensors in integrated circuits.

Different approaches combining Finite Element Simulations and in-situ electrical measurement of stress sensors during a BABSI test are proven to be ideal combination to quantitatively compare the strength of BEOL layers. It is shown that detectable mechanical failures during a shear or BABSI test are insufficient to detect early opens of the metal interconnections. A good agreement was found between the applied loads to the BEOL stack, the response of stress sensors below the Cu pillar and finite element simulations. Next, the risk of cohesive and adhesive failures in the Cu/low-k layers is evaluated in function of stiffness of low-k and design of metal interconnections.

In this work the effects of 3D stacking technology on the performance of devices are systematically studied. For this study a special chip consisting of a number of stress sensors and vertical interconnect loops was designed and manufactured in 65 nm technology. Local variations of stress with a magnitude of up to 300 MPa are detected at different locations along the chip and are being characterized using finite element modeling and micro-Raman spectroscopy measurements.

Stress measurements in microelectronic packaging through piezoresistive sensors take the advantage of both in-situ and nondestructive. In this study, test chips with both p-type and n-type piezoresistive stress sensors, as well as a heat source, were first designed, then manufactured by a commercialized foundry so that the uniformity of the test chips was expected. Both temperature and stress calibrations were next performed through a special designed MQFP (Metal Quad Flat Package) and four-point bending (4PB) structure, respectively. Measurements of stresses which are produced due to both manufacturing process and thermal effects on the test chips were finally executed, and approximately linear relationships were observed between stress and temperature as well as stress and input power. It is concluded that n-type piezoresistive stress sensors are able to extract stress in microelectronic packaging with good accuracy.

On sport players using raket and bat and general persons, sensory evaluation of the optimum diameter in grasping cylindical object and the movable angle of wrist joint under the grasping were investigated, and the effcts of the fingers in the six movements of wrist joint (Horizontal movement : Palmar-flexion and Dorsi-flexion, Vertical movement : Radial-flexion and Ulnar-flexion, Twist movement : Supination and Pronation) were investigated using stress sensors attached on the fingers. The subjects were ordinary persons and players of badminton, baseball and tennis, and the obtained data were compared to each other. The optimum diameters of the grasping evaluated by sport players were ranging from 30 mm to 40 mm, these values were same as that of ordinary persons, and the average values of optimum diameter were almost same as grip diameters of raket and bat. About movable angle of wrist joint under the grasping, badminton players could move horizontally and twist at larger angle and fielders could move vertically at larger angle. About the grasping force of fingers, the maximum force was exhibited at the tip of index finger for sport players, on the other hand, it was exhibited at the tip of middle finger for ordinary persons. It was considered that the specific training has effect on the sport players in the movable angle of wrist joint and in the finger's way of using at the movement of wrist joint.

The influence of mechanical stresses upon the offset of merged lateral bipolar magnetotransistors (LMTs) is studied. The experimental setup for analyzing the response of such structures to torsional and flexural stresses is briefly described. It has been found that their sensitivity to torsional stresses is much higher than to flexural stresses, and this may be explained in terms of the piezojunction effect which gives rise to emitter injection modulation (EIM), a phenomenon analogous to the one previously reported to explain the magnetic response of some types of LMTs. Other analogies between the response to mechanical stresses and to a magnetic field are described. Two different modes of electrical connections of the four collectors of the device are analyzed: cross-coupled and parallel. The parallel connection allows some degree of compensation of the offset due to torsional stresses, whereas the cross-coupled one is more sensitive to flexural stresses. It is concluded that: (1) the response to a magnetic field and a mechanical stress have many common aspects; (2) the piezojunction effect is the fundamental mechanism behind the measured sensitivity; and (3) these devices are potentially excellent stress sensors.

Pressure and frictional stress acting on the ripper point surface have been directly measured in the actual rock ripping process using stress sensors embedded in the top part of the ripper point. In the case of ripping sand stone ground, applied stresses are relatively low but sometimes increase rapidly, unless the traction force is constant. In the case of ripping conglomerate ground, large stress is applied to the top of the point surface and changes in proportion with the traction force. Point surface temperature has been also measured using an embedded temperature sensor. The temperature increases intermittently during the ripping process.

Although adaptive strategies based on the Measure-and-Control (M&C) design paradigm have been proven to be effective methods to achieve aging resilient circuits, their implementation requires accurate monitoring architectures and integrated aging sensors. This paper presents a new on-chip, fully digital monitoring architecture for tracking BTI-induced aging effects on digital ICs. The proposed solution is based on delay-to-threshold coherency of MOS devices and measures differential delay across pass-transistor chains. The aging monitor is conceived and designed as a self-contained standard gate consisting of reference and under stress sensors with embedded measurement circuitries and a control structure for data capturing. To guarantee independent measurements of both Positive- and Negative-BTI, two separate aging sensor blocks are used. Detailed SPICE simulations conducted for a low-power 40nm CMOS technology indicates the actual capability of the proposed circuit to capture BTI-induced aging.

The MOSFET (Metal-Oxide-Semiconductor Field-Effective-Transistor) has the potential to be a suitable chip stress monitoring tool for microelectronic packaging because the measurements are nondestructive, in-situ, real-time, and the sensor is relatively small. To this end, this paper studies the stress behaviors of both types of the MOSFET micro stress sensors. In this work, a self-developed four-point bending (4PB) measurement methodology is employed and the stress coefficient calibrations on the MOSFET sensors were next performed. After measurements, stress coefficients for both types of the MOSFET were successfully extracted with discussions. After comparing with the previous extracted temperature coefficients on the same devices, it is also concluded that the temperature effect is extremely important for the MOSFET sensor applications.

This paper discusses the adaptation of a novel bionic approach of AI to an Assisted Powered Wheelchair (APW) controller, in order to facilitate its driving by people with severe impairments. The control unit offers three modes of operation and this proposal refers to the second control that assists the wheelchair user in driving tasks like passing a door or avoiding obstacles. The user's psychic condition is considered in the APW navigation decision and it is determined by a stress detection system composed by electrocardiogram and skin conductance sensors. The control unit has to deal with environmental and stress data and must trigger actuating commands. The prototype implementation will be done within the platform STAGE and afterwards it will be embedded in a real powered wheelchair.

To make and maintain deep underground openings, it is important to predict the mechanical phenomena accompanying their excavations in terms of the rockmass properties and the geological structures. In this paper, a large-scaled two dimensional strata model testing method has been developed to approach these problems. In the adopted system, it is possible to excavate cavities in the model under loading condition.At first, some preliminary tests were performed to ensure the stress state created in the model by the loading system as well as the sensitivities of the built-in type sensors employed. Then, the test for a closely located two parallel excavations was performed. Two types of fractures were developed from the openings, which are interpreted, based on the corresponding finite element calculations, to be shear and tensile failures. The stress sensors recorded the local changes (increase and relief) in the model, with accompanying progress of excavation. P-wave velocity and the amplitude of its first motion increased with stress, and decreased on failure.It is concluded that this testing method can almost simulate various circumstances for the underground openings.

In accordance with the theory of magnetoelasticity, the magnetic properties of ferromagnetic materials depend dramatically on the stress level. As an engineering application of the said theory, the magnetoelastic (EM) stress sensor has been used in the stress monitoring of civil infrastructure. In this section, the theoretical background of EM stress sensors is reviewed, its technical methodology is introduced, and the influence of temperature is clarified. Through the application of EM stress sensors in representative infrastructures, their promising engineering advantages have been demonstrated, which is a prelude to a viable application stage.

This paper is focus on the applications of EM sensor on cable force measurement for large bridges. The sensors are entirely suitable for sheathed cables and require no physical contact with the cable itself. In order to meet the requirement of observing structure behavior under extreme events, a high sampling rate of EM technology has been developed. The sampling rate of the EM sensor can be as high as 0.1 Hz which is faster than the current available technology for sensor size of up to 250mm. Both laboratory and field calibrations were conducted. The relationship between the relative incremental permeability and tensile stress is derived from these calibrations. Field measurements on tendons for Stonecutters Bridge in Hong Kong demonstrate the reliability and accuracy of the EM stress sensors using the updated technology.

As so-called wooden rounds, which are intended to sit stably in storage for extended periods and then function precisely as desired at a moment's notice, missiles would appear to be an ideal application for health monitoring. However, the solid rocket motors that serve as the propulsion system for these missiles present a number of unique challenges for the development of integrated vehicle health monitoring systems. Mechanical and chemical complexity, long service lives, aging materials, and designs with small margins are typical for solid motors, but the payoff for health monitoring is extreme as well. Maintaining a healthy and capable fleet—ensuring the viability of the missiles in the fleet, while not retiring or destroying good assets before it is necessary—could save as much as 50% in costs over a 50-year life cycle. In this article, a number of unique aspects of solid rocket motors are explored, the difficulties and successes in the development of sensors and diagnostic systems are discussed, and a path to further continue the development of these systems is proposed. Keywords: solid rocket motors; stress sensors; bondline; chemical aging; mechanical damage

We propose a tactile sensing cube that is a rectangular rigid body with symmetrically-located stress sensors and embedded in an elastic body. The sensor measures stress tensor applied to the elastic body and can distinguish between shear and non-uniformly distributing normal stress applied to the surface of the body. The previously reported tactile sensors could not distinguish these stresses. In this paper, we verify the detection principle qualitatively by FEM simulation of two dimensional model and we show the result of basic experiments using a prototype.

This month's issue has the following articles: (1) Bridging the Gap between Scientific Discovery and Solutions to National Needs--Commentary by Steven R. Patterson; (2) Measuring Contact Stress inside Weapon Systems--New stress sensors allow researchers to measure loads inside weapon systems for the first time; (3) Transparent Ceramics Spark Laser Advances--A team of Livermore researchers is acquiring advanced transparent ceramics that can handle the high heat loads and optical requirements needed for high-power lasers; (4) Studying the Behavior of Crystal Deformation in Three Dimensions--Three-dimensional image correlation gives materials scientists a more accurate understanding of the behavior of single crystals; and (5) An Accelerated Collaboration Meets with Beaming Success--A Livermore/Los Alamos collaboration tested key components for the Los Alamos DARHT Facility--an accelerator for producing intense x rays for flash radiography.

Over the past twenty or so years research programs investigating structural health monitoring of rocket motors has resulted in significant progress. On the experimental side the physics of fibre optic strain sensors, micro-electronic stress transducers, and chemical sensing devices have become more mature and several devices have achieved a technical readiness level of five and above. However, the specific applications to health monitoring of solid rocket motors, the details of implementation, calibration, safety and the associated algorithms are still under development. This paper will review current embedded sensors technology and give, in general terms, the recommended practices on how to select, install, calibrate and process data obtained from stress sensors installed in rocket motors filled with energetic materials. As well as, “lessons learned” when using these sensors to evaluate the health of a rocket motor, typical results will be shown and discussed to illustrate the potential of the technology.

In this paper, the calibration and workability of magnetoelastic (ME or EM) stress sensors for large steel cables used in Qiangjiang 4th bridge in China are discussed. As an engineering application of magnetoelasticity, EM sensors make non-contact stress monitoring possible for steel hangers and post-tensioned cables on suspension and cable-stayed bridges, and other ferromagnetic structures. By quantifying the correlation of tension with magnetic properties represented by the relative permeability of the steel structure itself, the EM sensor inspects the loading level of the steel structure. The tension dependence of the relative permeability and the temperature influence was calibrated. The results revealed that the magnetoelasticity of the multi-wire hangers is consistent with one another, while the post-tensioned cables are similar to single wires. Cable stress monitoring on Qiangjiang (Qj) 4th bridge demonstrated the reliability of the EM sensors in safety evaluation of bridge.

Development of autobiased linear field sensors based on asymmetrical giant magnetoimpedance (AGMI) effect in Corich amorphous microwires upon the application of a biasing dc current is approached. Upon biasing dc currents, the highest field sensitivity of AGMI of 20%/Oe was found at a biasing dc current of 10 mA. The reduction of the AGMI under a biasing dc current of 25 mA and a frequency of 10 MHz has been observed. The result indicates that an optimum design of autobiased linear field sensors based on AGMI can be achieved by applying the biasing dc current of 10 mA and in the frequency range of 100 kHz–5 MHz. A stress-induced change in AGMI has also been found in these microwires and this offers a new approach to the development of stress sensors. All these features make the Co-rich amorphous microwire a multifunctional and smart material that can be used for different purposes of sensing applications.Copyright © 2004 by ASME

In advanced robotic applications where a physical interaction of the robot with the environment takes place, the measurement of interaction forces is of basic importance for a safe execution of the desired tasks. In the paper, a 'stress' sensor is presented and its basic characteristics illustrated and discussed. Among its positive features, one may find the very compact size, good electrical properties, and the fact that it can be easily 'constructed' directly on the mechanical part by deposition of the sensing elements directly on the mechanical structure. These are very interesting properties for its use in advanced robotic systems.

In this work, a simple assembled structure was designed and fabricated so that the calibration procedures on piezoresisitve stress sensors for microelectronic packaging can be simpler, more accurate, and more efficient. After comparing with the previous work results, validity of the aforementioned new structure was next demonstrated through experimental data. Since many accessory experimental facilities employed in traditional calibration procedure become unnecessary, the new methodology takes great advantage on piezoresisitve coefficient calibrations, especially for calibration at temperature other than room temperature.

Despite the increasing popularity of cable-stayed bridges there is no convenient and accurate means available to measure the forces in the cable stays. The measurement of the forces is important for monitoring excessive wind or traffic loadings, to gage the redistribution forces which may occur after seismic events, and for detecting corrosion via loss of the cross-section. Although magnetoelastic stress sensors have been extensively tested on many types of prestressing cables, and have demonstrated accuracies of < 1%, to-date they have been based upon a solenoid geometry, which is not practical for cable force measurements in existing bridges having hundreds of cables. In order to address this problem a magnetoelastic sensor for the direct measurement of stress in steel cables is currently under development. The sensor differs from previous magnetoelastic sensors in that the cable is magnetized by a removable C- shaped circuit, rather than by a solenoid. We report preliminary results on measurement of the initial permeability curve indicating adequate sensitivity to stress with this geometry, but further work is necessary to understand the influence of the more complicated field geometry on data reduction and calibration procedures.