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Embedded stress sensors have previously been employed as part of health monitoring systems for solid rocket motors; however, the sensor readings were used to detect anomalies such as bore cracks an...

Mechanoluminescence (ML) is the emission of light consecutive to a mechanical force or stress imposed to a crystalline material. Many inorganic and organic compounds present this phenomenon that is known for over 400 years. Lanthanide and uranyl salts were among the first substances investigated for this property. Mechanoluminescence, also referred to as triboluminescence, is often considered as being a badly understood phenomenon. In fact it is because of two main reasons. Firstly, a variety of different mechanical stresses, from simple rubbing, to applied pressure, crushing, impact of a weight, ultrasound, laser-generated shock wave, crystallization, dissolution of crystals, or even wind can trigger it. Secondly, ML is very sensitive to the purity and morphology of the sample: in inorganic compounds, generation of traps by doping "impurities" (e.g. lanthanide ions) is responsible for light emission so that the exact composition of the sample has to be known to a very detailed level; for chelates, the crystallization conditions are crucial since they often generate extended networks of weak interactions that are instrumental in triggering ML when they are broken. In fact mechanisms of ML are relatively well known and theories and models often reproduce very well the experiments. Additionally, practical applications are at hand, for example stress, crack, and impact sensors based on SrAl2O4: Eu-II or Et3NH[Eu(dbm)(4)] are used to test structures and materials as diverse as road bridges, reinforced concrete elements, pressurized containers or airplane wings and to image the propagation of cracks or stress distribution. Military and security applications involve detecting the passage of vehicle or soldiers and producing counterfeiting inks while more joyful applications are luminous balls, wrapping papers and adhesive tapes. Not only bulk materials, but micro- and nanoparticles feature mechanoluminescent properties and single particle manipulation under an AFM allows one to produce light sources that could be useful to several photonic applications, including bio-applications. The review starts with a short historical background of ML, discussing definitions, and providing some theoretical bases. It then presents instrumental setups before covering all aspects of lanthanide mechanoluminescence, starting with simple salts, then doped inorganic compounds (irradiated and non-irradiated) and finally chelates. Mechanoluminescent sensors are described with various actual and potential applications. Literature is covered until April 2017. The wealth of information gathered during the past 20 years in the field and the broad understanding of the phenomenon attained show that the field is presently ready for a quantitative leap forward. Many subjects are waiting to be developed, including NIR mechanoluminescence or bio-applications based on single mechanoluminescent particle light sources; in addition, designing new types of mechanoluminescent materials with techniques paralleling the developments in other aspects of lanthanide photonics could prove extremely rewarding. (C) 2018 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

The regenerated silk fibroin is developed to soft graphene aerogels for application in stress sensor. The resultant graphene aerogel owns a low density of 14.1 mg cm−3 with high mass specific capacitance of 128.4 F g−1. When a single aerogel serving as elastic medium, a supercapacitive stress sensor is established to offer high sensitivity of 0.73 kPa−1 in ranging 0.01–10 kPa. In contract, the sensor based on original graphene aerogel just shows a sensitivity of 0.04 kPa−1. Further, the sensing stability of the optimized sensor can retain 87% under constant pressure intensity of 1 kPa for 1000 cycles. The soft effect can be attributed to the regenerated silk fibroin by intercalation in preparation, and the simulated results show that the stress response originated from the variation of ion concentration in the electrochemical system.

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.

Visualization and quantitative evaluation of covalent bond scission in polymeric materials are critical in understanding their failure mechanisms and improving the toughness and reliability of the materials. Mechano-responsive polymers with the ability of molecular-level transduction of force into chromism and luminescence have evoked major interest and experienced significant progress. In the current review, we highlight the recent achievements in covalent mechanochromic and mechanoluminescent polymers, leading to a bridge between macroscopic mechanical properties and microscopic bond scission events. After a general introduction concerning polymer mechanochemistry, various examples that illustrate the strategies of design and incorporation of functional and weak covalent bonds in polymers were presented, the mechanisms underlying the optical phenomenon were introduced and their potential applications as stress sensors were discussed. This review concludes with a comment on the opportunities and challenges of the field.

Centimetric capacitive sensors made out of PDMS foams of controlled porosity are fabricated and electromechanically characterized under either normal stress and shear stress. For normal stress characterizations, it can be concluded that the density of the foam strongly affects the sensor performances expressed in sensitivity and measurement range thanks to dedicated behavioral sensor models. Also, it was found that the actual size of the foam pores plays a minor role in the electromechanical behavior of the sensor. Similar conclusions can be derived shear stress sensor characterizations. This work opens the way to the design of flexible sensors with adjustable performances for normal and shear stress measurements.

The unfolded protein response (UPR) is a collection of cellular feedback mechanisms that seek to maintain protein folding homeostasis in the endoplasmic reticulum (ER). When the ER is “stressed”, either through high protein folding demand or undersupply of chaperones and foldases, stress sensing proteins in the ER membrane initiate the UPR. Recently, experiments have indicated that these signaling molecules detect stress by being both sequestered by free chaperones and activated by free unfolded proteins. However, it remains unclear what advantage this bidirectional sensor control offers stressed cells. Here, we show that combining positive regulation of sensor activity by unfolded proteins with negative regulation by chaperones allows the sensor to make a more informative measurement of ER stress. The increase in the information capacity of the combined sensing mechanism stems from stretching of the active range of the sensor, at the cost of increased uncertainty due to the integration of multiple signals. These results provide a possible rationale for the evolution of the observed stress sensing mechanism.

Combining functional nanomaterials composite with three-dimensional graphene (3DG) is a promising strategy for improving the properties of stress sensors. However, it is difficult to realize stress sensors with both a wide measurement range and a high sensitivity. In this paper, graphene-SiO2 balls (GSB) were composed into 3DG in order to solve this problem. In detail, the GSB were prepared by chemical vapor deposition (CVD) method, and then were dispersed with graphene oxide (GO) solution to synthesize GSB-combined 3DG composite foam (GSBF) through one-step hydrothermal reduction self-assembly method. The prepared GSBF owes excellent mechanical (95% recoverable strain) and electrical conductivity (0.458 S/cm). Furthermore, it exhibits a broad sensing range (0&ndash, 10 kPa) and ultrahigh sensitivity (0.14 kPa&minus, 1). In addition, the water droplet experiment demonstrates that GSBF is a competitive candidate of high-performance materials for stress sensors.

In recent years, mechanoluminescence from polymers is emerging as a new cutting-edge area of polymer mechanochemistry research. It refers to the release of energy from polymers in the form of light when they are under various mechanical stimuli. To spur more researchers to join in such interesting and new burgeoning area, and promote its development to practical applications, in this review, we try to briefly summarize the recent advances in mechanoluminescent polymers with the aspects of non-covalent, covalent, and cascade reactions systems. We pay much attention on the applications of such polymer systems in molecular level failure and stress sensors, and give a perspective of their potential applications in novel energy conversion materials and devices, as well as self-healing materials.

Structural health monitoring (SHM) plays a major role in industry and engineering today, as this methodology has completely changed the paradigm of how to assess the health status of structures. Previously, the methodology of reference, Non-Destructive Testing (NDT), consisted on conducting periodic inspections, made by specialized professionals that used external equipment. However, this method was quite expensive and time consuming. SHM systems are considered as an alternative to traditional methods, since these systems allow the continuous acquisition of the structural responses from the disturbances experienced by the structure. Through the measurement data, it will be possible to know the health condition of the structure and the existence of structural damages. Sensors represent a fundamental component of these systems, since they are responsible for the acquisition of data related to the health and integrity of the structures and they should be accessible, light and discrete, so as not to impose cost and weight on the structure and not to interfere with the structural resistance. Although the THz domain is a relatively new field of research in electromagnetic sensors, it is known that the use of frequency selective surfaces (FSSs) allows the creation of compact devices which can be easily integrated into the surface of the structures without harming its functionality and aesthetic appearance. The main goal of this dissertation is to study and numerically simulate stress sensors for the detection of THz radiation for applications in SHM, with high sensitivity and selectivity. Taylloring these characteristics to provide a good detection has been achieved through appropriate selection of materials and careful design of stress tunnable band pass filters for the THz domain. Numerical modelling of both the mechanical and electromagnetics, solving the elasticity equation and Maxwell’s equations, respectively, has been undertaken for two types of assembling of the devices using different thermoplastic polymers such as high-density polyethylene (HDPE) and polytetrafluoroethylene (PTFE). It was observed that two methodologies can be adopted to control the level of force applied to the sensors, namely through, the variation of the electric current and the positioning of the coil on the plunger. A monitorização de saúde estrutural (SHM) desempenha um papel bastante importante na indústria e na engenharia hoje em dia, uma vez que esta metodologia mudou completamente o paradigma de como aferir o estado de saude das estruturas. Anteriormente, a metodologia de referência consistia em realizar inspeções periódicas com recurso a equipamentos externos, as quais eram realizadas por profissionais especializados. Contudo, este método revelou ser bastante dispendioso e moroso. Os sistemas SHM são considerados uma alternativa aos métodos tradicionais, uma vez que esses sistemas permitem a aquisição contínua das respostas estruturais provenientes das perturbações experimentadas pela estrutura e saber qual o estado de saúde da estrutura com base nas medições efectuadas. Os sensores são base destes sistemas, devendo ser acessíveis, leves e discretos, para não impor custo e peso à estrutura e não interferir na resistência estrutural. Apesar da vasta gama de sensores disponíveis, existe alguma carência de sensores altamente selectivos para o domínio dos Terahertz. Embora o domínio THz seja um campo relativamente novo de investigação em sensores eletromagnéticos, sabe-se que o uso de superfícies seletivas de frequência (FSSs) permite a criação de dispositivos compactos que podem ser facilmente integrados na superfície das estruturas sem prejudicar sua funcionalidade e aspecto estético. O objetivo principal desta dissertação é estudar e simular numericamente sensores de stress para a detecção de radiação THz para aplicações em SHM, com alta sensibilidade e seletividade. A determinação dessas características para fornecer uma boa detecção foi conseguida através da seleção apropriada de materiais e do design cuidadoso de filtros passa-banda sintonizáveis por tensão para o domínio dos THz. Foram realizadas simulações numéricas das componentes mecânica e electromagnética dos sensores com objectivo de resolver a equação de elasticidade e as equações de Maxwell respectivamente, para dois tipos de montagem dos dispositivos, utilizando diferentes polímeros termoplásticos, tais como polietileno de alta densidade (HDPE) e politetrafluoretileno (PTFE). Observou-se que podem ser adotadas duas metodologias para controlar o nível de força aplicado aos sensores, tais como a variação da corrente elétrica e o posicionamento da bobina no êmbolo.

Stress sensors have shown potential to provide “health monitoring” of a wide range of issues related to packaging of integrated circuits, and silicon carbide offers the advantage of much higher temperature sensor operation with application in packaged high-voltage, high-power SiC devices as well as both automotive and aerospace systems, geothermal plants, and deep well drilling, to name a few. This paper discusses the theory and uniaxial calibration of resistive stress sensors on 4H silicon carbide (4H-SiC) and provides new theoretical descriptions for four-element resistor rosettes and van der Pauw (VDP) stress sensors. The results delineate the similarities and differences relative to those on (100) silicon: resistors on the silicon face of 4H-SiC respond to only four of the six components of the stress state; a four-element rosette design exists for measuring the in-plane stress components; two stress quantities can be measured in a temperature compensated manner. In contrast to silicon, only one combined coefficient is required for temperature compensated stress measurements. Calibration results from a single VDP device can be used to calculate the basic lateral and transverse piezoresistance coefficients for 4H-SiC material. Experimental results are presented for lateral and transverse piezoresistive coefficients for van der Pauw structures and p- and n-type resistors. The VDP devices exhibit the expected 3.16 times higher stress sensitivity than standard resistor rosettes.

The conjecture discussed in our previous paper [Jaeger, R. C., Motalab, M., Hussain, S., and Suhling, J. C., 2014, “Four-Wire Bridge Measurements of Silicon van der Pauw Stress Sensors,” ASME J. Electron. Packag., 136(4), p. 041014; Jaeger, R. C., Motalab, M., Hussain, S., and Suhling, J. C., 2018, Erratum: “Four-Wire Bridge Measurements of Silicon van der Pauw Stress Sensors,” ASME J. Electron. Packag., 140(1), p. 017001] was backed up by measurements and simulation results, but not mathematically proven. A proof based upon two-port impedance parameter reciprocity is presented with additional experimental confirmation.

The conjecture discussed in the referenced paper was backed up by measurements and simulation results, but not mathematically proven. A proof based on impedance parameter reciprocity is presented, and a sign error is corrected.

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].

The physical and operating principle of a stress sensor, based on two crossing carbon fibers functionalized with ZnO nanorod-shaped nanostructures, was recently demonstrated. The functionalization process has been here extended to tows made of one thousand fibers, like those commonly used in industrial processing, to prove the idea that the same working principle can be exploited in the creation of smart sensing carbon fiber composites. A stress-sensing device made of two functionalized tows, fixed with epoxy resin and crossing like in a typical carbon fiber texture, was successfully tested. Piezoelectric properties of single nanorods, as well as those of the test device, were measured and discussed.

To overcome endoplasmic reticulum (ER) stress, ER-localized stress sensors actuate distinct downstream organelle-nucleus signaling pathways to invoke a cytoprotective response, known as the unfolded protein response (UPR). Compared to yeast and metazoans, plant UPR studies are more recent but nevertheless fascinating. Here we discuss recent discoveries in plant UPR, highlight conserved and unique features of the plant UPR as well as critical yet-open questions whose answers will likely make significant contributions to the understanding plant ER stress management.

The family of interferon regulatory factors (IRFs) consists of nine members (IRF1-IRF9) in mammals. They act as transcription factors for the interferons and thus exert essential regulatory functions in the immune system and in oncogenesis. Recent clinical and experimental studies have identified critically important roles of the IRFs in cardiovascular diseases, arising from their participation in divergent and overlapping molecular programmes beyond the immune response. Here we review the current knowledge of the regulatory effects and mechanisms of IRFs on the immune system. The role of IRFs and their potential molecular mechanisms as novel stress sensors and mediators of cardiovascular diseases are highlighted.

Magnetoimpedance (MI) and field sensitivity of CoFeSiB amorphous ribbons were investigated at frequencies ranging from 0.2 to 12 MHz after tensile stress applied. Experimental results indicate that the MI of amorphous ribbons can be significantly improved by applying a suitable longitudinal tensile stress. Applying tensile stress induces a rearrangement of domain walls which influences the circumferential anisotropy and magnetic permeability result in improving the MI response. The maximum MI response of 145 % and maximum field sensitivity of 6.32 %/Oe at frequency of 4 MHz were obtained, when tension was equivalent to 120 MPa. So the tensile stress as new method can be effective, cheap, and fast in sensor applications, and result of this investigation can be applied for the design of the stress sensors based on the giant magnetoimpedance effect.

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.

For the construction of Shipbord solid rocket motor life cycle health management system based on embedded sensors the stress calculation of SRM interface under different loading conditions, the monitoring range of embedded interface stress sensors used for health management system was determined. As a result, it is found that the variation range of the solid motor's interface shear stress under the given shipboard condition is 0KPa-6KPa, The variation range of the solid motor's interface normal stress under the given alternating temperature loads is 0.05MPa-0.13MPa. Considering design redundancy, the stress monitoring process of the interface shear stress sensor and the normal stress sensor shall be not less than 10KPa and 1MPa. The research results can provide technical support for the development of life cycle management system of solid rocket motor, and have a great significance to improve the reliability of missile weapon system and life prediction.

Kinked silicon nanowires (KSiNWs) have many special properties that make them attractive for a number of applications. The mechanical properties of KSiNWs play important roles in the performance of sensors. In this work, the effects of defects on the mechanical properties of KSiNWs are studied using molecular dynamics simulations and indirectly validated by experiments. It is found that kinks are weak points in the nanowire (NW) because of inharmonious deformation, resulting in a smaller elastic modulus than that of straight NWs. In addition, surface defects have more significant effects on the mechanical properties of KSiNWs than internal defects. The effects of the width or the diameter of the defects are larger than those of the length of the defects. Overall, the elastic modulus of KSiNWs is not sensitive to defects; therefore, KSiNWs have a great potential as strain or stress sensors in special applications. Electronic supplementary material The online version of this article (doi:10.1186/s11671-017-1970-7) contains supplementary material, which is available to authorized users.

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.

Packaging-induced die-stresses due to temperature effects on various materials of the package are characterized using piezoresistive van der Pauw stress sensors over a temperature range of −180° C to 80° C. Piezo-resistive coefficients extracted previously are then used to obtain a mapping between change in resistance and corresponding stress at all tested temperatures. The obtained values of stress are compared with finite element simulation results.

Mechanoluminescence (ML) is a type of luminescence induced by any mechanical action on solids. The light emissions induced by elastic deformation, plastic deformation and fracture of solids are called elastico ML (EML), plastico ML (PML) and fracto ML (FML), respectively. Whereas nearly 50% of all organic molecular solids and inorganic salts exhibit FML, only a few solids exhibit EML and PML. The EML and FML of certain solids are so intense that they can be seen during daylight with the naked eye. Mechanolumnescence has a great potential for use in different types of mechano-optical devices such as stress sensors, damage sensors, impact sensors, fracture sensors and safety management monitoring systems. This article reports a survey of the literature from 1605 to 2013. Mechanoluminescence is studied by physicists, chemists, material scientists, geologists, medical scientists, engineers and technologists, among others and researchers will certainly benefit from the literature survey on ML given here. In addition, the field of mechanoluminescence may attract the interest of many new researchers.

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

The wearing process of an ultrahigh molecular weight polyethylene (UHMWPE) bearing surface in orthopaedic surgical implants cannot be tracked at present; hence, implant failure only becomes apparent when the patient experiences some discomfort. In exploring the integration of wireless stress sensors into UHMWPE, this paper describes the first step in achieving in vivo monitoring of implant wear using magnetostrictive amorphous ribbons.

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.

We have fabricated p- and n-type resistor stress sensors on (111) silicon surface and investigated the strain effects, which were generally ignored in previous works, for the precise stress measurements. We obtained the corrected values of the pi-coefficients for p- and n-type silicon by considering the strain effects, without which more than 25% discrepancies may be induced for small pi-coefficients. We observed that ignoring the strain effects was one of the potential errors which induce large discrepancies in stress measurements, especially for n-type stress sensors on (111) silicon.

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.

For many diseases, where a particular organ is affected, chemical by-products can be found in the patient’s exhaled breath. Breath analysis is often done using gas chromatography and mass spectrometry, but interpretation of results is difficult and time-consuming. We performed characterization of patients’ exhaled breath samples by an electronic nose technique based on an array of nanomechanical membrane sensors. Each membrane is coated with a different thin polymer layer. By pumping the exhaled breath into a measurement chamber, volatile organic compounds present in patients’ breath diffuse into the polymer layers and deform the membranes by changes in surface stress. The bending of the membranes is measured piezoresistively and the signals are converted into voltages. The sensor deflection pattern allows one to characterize the condition of the patient. In a clinical pilot study, we investigated breath samples from head and neck cancer patients and healthy control persons. Evaluation using principal component analysis (PCA) allowed a clear distinction between the two groups. As head and neck cancer can be completely removed by surgery, the breath of cured patients was investigated after surgery again and the results were similar to those of the healthy control group, indicating that surgery was successful.

Since GMI changes as a function of external dc magnetic field or applied dc/ac current, it is possible to design and produce GMI-based sensors that can measure either magnetic fields or dc/ac currents. GMI also changes sensitively with applied stress, and this provides a new opportunity to develop stress sensors. A brief description of these typical sensors is given in this chapter. It shows that the high sensitivity of GMI to applied magnetic field, current, and external stress is very useful for a wide range of industrial and engineering applications.