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Stress is an elevated psycho-physiological state of the human body, arising in response to a difficult event or stressful situation. Environmental factors that cause pressure are referred to as stressors. Prolonged exposure to multiple stressors simultaneously can adversely affect a person's mental and physical health, potentially leading to chronic health issues. The negative effects of mental stress on human health have been recognized for decades. High levels of stress should be detected early to prevent these adverse effects. While the stress response helps the body overcome challenges and prepare for threats, prolonged stress can harm health. This paper aims to design a basic, cost-effective, low-power smart band for healthcare that detects mental stress based on skin conductance. This band can continuously monitor the user's mental stress and wirelessly transmit stress-related data to the user's smartphone. It not only helps users better understand their stress levels but also provides physicians with reliable data for improved treatment. The inputs to this tool come from various alerts generated by different sensors. [ABSTRACT FROM AUTHOR]

Physical sensors have emerged as a promising technology for real‐time healthcare monitoring, which tracks various physical signals from the human body. Accurate acquisition of these physical signals from biological tissue requires excellent electrical conductivity and long‐term durability of the sensors under complex mechanical deformation. Conductive polymers, combining the advantages of conventional polymers and organic conductors, are considered ideal conductive materials for healthcare physical sensors due to their intrinsic conductive network, tunable mechanical properties, and easy processing. Doping engineering has been proposed as an effective approach to enhance the sensitivity, lower the detection limit, and widen the operational range of sensors based on conductive polymers. This approach enables the introduction of dopants into conductive polymers to adjust and control the microstructure and energy levels of conductive polymers, thereby optimizing their mechanical and conductivity properties. This review article provides a comprehensive overview of doping engineering methods to improve the physical properties of conductive polymers and highlights their applications in the field of healthcare physical sensors, including temperature sensors, strain sensors, stress sensors, and electrophysiological sensing. Additionally, the challenges and opportunities associated with conductive polymer‐based physical sensors in healthcare monitoring are discussed. [ABSTRACT FROM AUTHOR]

Abstract Identification of environmental stress sensors is one of the most important research topics in plant abiotic stress research. Traditional strategies to identify stress sensors or early signaling components based on the cell membrane as a primary site of sensing and calcium signal as a second messenger have had only limited successes. Therefore, the current theoretical framework underlying stress sensing in plants should be reconsidered and additional mechanisms need to be introduced. Recently, accumulating evidence has emerged to suggest that liquid-liquid phase separation (LLPS) is a major mechanism for environmental stress sensing and response in plants. In this review, we briefly introduce LLPS regarding its concept, compositions, and dynamics, and then summarize recent progress of LLPS research in plants, emphasizing the contribution of LLPS to the sensing of various environmental stresses, such as dehydration, osmotic stress, and low and high temperatures. Finally, we propose strategies to identify key proteins that sense and respond to environmental stimuli on the basis of LLPS, and discuss the research directions of LLPS in plant abiotic stress responses and its potential application in enhancing stress tolerance in crops.

Identification of environmental stress sensors is one of the most important research topics in plant abiotic stress research. Traditional strategies to identify stress sensors or early signaling components based on the cell membrane as a primary site of sensing and calcium signal as a second messenger have had only limited successes. Therefore, the current theoretical framework underlying stress sensing in plants should be reconsidered and additional mechanisms need to be introduced. Recently, accumulating evidence has emerged to suggest that liquid-liquid phase separation (LLPS) is a major mechanism for environmental stress sensing and response in plants. In this review, we briefly introduce LLPS regarding its concept, compositions, and dynamics, and then summarize recent progress of LLPS research in plants, emphasizing the contribution of LLPS to the sensing of various environmental stresses, such as dehydration, osmotic stress, and low and high temperatures. Finally, we propose strategies to identify key proteins that sense and respond to environmental stimuli on the basis of LLPS, and discuss the research directions of LLPS in plant abiotic stress responses and its potential application in enhancing stress tolerance in crops. [ABSTRACT FROM AUTHOR]

Abiotic stress is the adverse effect of any abiotic factor on a plant in a given environment, impacting plants' growth and development. These stress factors, such as drought, salinity, and extreme temperatures, are often interrelated or in conjunction with each other. Plants have evolved mechanisms to sense these environmental challenges and make adjustments to their growth in order to survive and reproduce. In this review, we summarized recent studies on plant stress sensing and its regulatory mechanism, emphasizing signal transduction and regulation at multiple levels. Then we presented several strategies to improve plant growth under stress based on current progress. Finally, we discussed the implications of research on plant response to abiotic stresses for high-yielding crops and agricultural sustainability. Studying stress signaling and regulation is critical to understand abiotic stress responses in plants to generate stress-resistant crops and improve agricultural sustainability. [ABSTRACT FROM AUTHOR]

Flexible piezoresistive sensors (FPSs) have the advantages of compact structure, convenient signal acquisition and fast dynamic response; they are widely used in motion detection, wearable electronic devices and electronic skins. FPSs accomplish the measurement of stresses through piezoresistive material (PM). However, FPSs based on a single PM cannot achieve high sensitivity and wide measurement range simultaneously. To solve this problem, a heterogeneous multi-material flexible piezoresistive sensor (HMFPS) with high sensitivity and a wide measurement range is proposed. The HMFPS consists of a graphene foam (GF), a PDMS layer and an interdigital electrode. Among them, the GF serves as a sensing layer, providing high sensitivity, and the PDMS serves as a supporting layer, providing a large measurement range. The influence and principle of the heterogeneous multi-material (HM) on the piezoresistivity were investigated by comparing the three HMFPS with different sizes. The HM proved to be an effective way to produce flexible sensors with high sensitivity and a wide measurement range. The HMFPS-10 has a sensitivity of 0.695 kPa−1, a measurement range of 0–14,122 kPa, fast response/recovery (83 ms and 166 ms) and excellent stability (2000 cycles). In addition, the potential application of the HMFPS-10 in human motion monitoring was demonstrated. [ABSTRACT FROM AUTHOR]

Flexible piezoresistive sensors (FPSs) have the advantages of compact structure, convenient signal acquisition and fast dynamic response; they are widely used in motion detection, wearable electronic devices and electronic skins. FPSs accomplish the measurement of stresses through piezoresistive material (PM). However, FPSs based on a single PM cannot achieve high sensitivity and wide measurement range simultaneously. To solve this problem, a heterogeneous multi-material flexible piezoresistive sensor (HMFPS) with high sensitivity and a wide measurement range is proposed. The HMFPS consists of a graphene foam (GF), a PDMS layer and an interdigital electrode. Among them, the GF serves as a sensing layer, providing high sensitivity, and the PDMS serves as a supporting layer, providing a large measurement range. The influence and principle of the heterogeneous multi-material (HM) on the piezoresistivity were investigated by comparing the three HMFPS with different sizes. The HM proved to be an effective way to produce flexible sensors with high sensitivity and a wide measurement range. The HMFPS-10 has a sensitivity of 0.695 kPa−1, a measurement range of 0–14,122 kPa, fast response/recovery (83 ms and 166 ms) and excellent stability (2000 cycles). In addition, the potential application of the HMFPS-10 in human motion monitoring was demonstrated.

The stress response allows the body to overcome obstacles and prepare for threats, but sustained levels of stress can damage one’s health. Stress has long been measured through physical tests and questionnaires that rely primarily on user-inputted data, which can be subjective and inaccurate. To quantify the amount of stress that the body is experiencing biologically, analytical detection of biomarkers associated with the stress response recently have been developed. Novel stress sensing devices focus on cortisol sweat sensing as a part of wearable, flexible devices. These devices promise a real-time, continuous collection of stress data that can be used in clinical diagnoses or for personal stress monitoring and mediation.

Ultralight flexible carbon aerogels have been applied in many fields but are always hampered due to their weak mechanical stability, large energy dissipation, and complex preparation methods. Here, a novel polyimide-derived carbon nanofiber aerogel with high fatigue resistance and excellent flexibility is prepared by using the designed "fiber gluing" to construct the elastic continuous fibrous network. The as-prepared carbon nanofiber aerogels exhibit ultralow density of 6.6 mg cm−3, excellent fire-resistant performance when exposing to alcohol flames (650 °C), and robust elastic resilience even under 55% compressive strain. In particular, the carbon nanofiber aerogels show ultralow plastic deformation (only 1.3%) and low energy dissipation (<0.22) after 1000 cyclic loading-unloading tests at 55% compressive strain. Benefiting from their excellent flexibility and robust mechanical stability, the as-prepared carbon nanofiber aerogel are a promising candidate in the application of wearable devices and piezoresistive stress sensors. [ABSTRACT FROM AUTHOR]

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.

[Display omitted] • Fabricated visible structural colors hydrogels response to mechanical stresses. • Developed clear and stretchable hydrogels interlocked with chiral nematic CNCs. • 2D-XRD analysis showed CNC alignment, but the chiral nematic CNC was maintained. • Simulation study revealed that some CNCs remained unaffected orientation angle. • Simulation revealed that AR of the CNCs plays an important role in orientation. It has been extensively reported that cellulose nanocrystals (CNCs) are capable of exhibiting structural colors due to their unique chiral nematic self-assembly. However, further investigation is required to effectively utilize these remarkable properties for addressing real-world challenges, such as development of advanced materials like mechanical sensors and smart wearable devices. One particular challenge has been maintaining the refractive properties of structural colors resulting from the CNCs structure within the visible spectrum. In this study, we introduce a one-step hydrogel fabrication method involving chiral nematic CNC films embedded within poly(acrylic acid). These hydrogels exhibit naked-eye-visible structural colors and exhibit responsiveness to mechanical stresses. The resulting photonic hydrogels exhibit a blue shift in response to mechanical stretching. The hydrogels demonstrated self-recovery capabilities, as observed through cyclic loading–unloading stress tests. The color of the materials was characterized using UV–Vis spectroscopy to determine the wavelength of the reflected light. Additionally, we investigated the mechanism of CNCs orientation change using 2D-X-ray diffraction. Demonstrated by our simulation study, the morphology of the CNC bundles significantly influenced the characteristics of the chiral nematic structure as they orient due to the force application. Notably, the color change of the photonic hydrogels was reversible within the optimal range of applied force and can be repeated numerous times. This work presents a new strategy for fabricating optically functional photonic hydrogels with stimuli-responsive properties, enabling their potential applications in biomedical engineering and wearable responsive sensor technologies. [ABSTRACT FROM AUTHOR]

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’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.

Climate change reshapes the physiology and development of organisms through phenotypic plasticity, epigenetic modifications, and genetic adaptation. Under evolutionary pressures of the sessile lifestyle, plants possess efficient systems of phenotypic plasticity and acclimation to environmental conditions. Molecular analysis, especially through omics approaches, of these primary lines of environmental adjustment in the context of climate change has revealed the underlying biochemical and physiological mechanisms, thus characterizing the links between phenotypic plasticity and climate change responses. The efficiency of adaptive plasticity under climate change indeed depends on the realization of such biochemical and physiological mechanisms, but the importance of sensing and signaling mechanisms that can integrate perception of environmental cues and transduction into physiological responses is often overlooked. Recent progress opens the possibility of considering plant phenotypic plasticity and responses to climate change through the perspective of environmental sensing and signaling. This review aims to analyze present knowledge on plant sensing and signaling mechanisms and discuss how their structural and functional characteristics lead to resilience or hypersensitivity under conditions of climate change. Plant cells are endowed with arrays of environmental and stress sensors and with internal signals that act as molecular integrators of the multiple constraints of climate change, thus giving rise to potential mechanisms of climate change sensing. Moreover, mechanisms of stress‐related information propagation lead to stress memory and acquired stress tolerance that could withstand different scenarios of modifications of stress frequency and intensity. However, optimal functioning of existing sensors, optimal integration of additive constraints and signals, or memory processes can be hampered by conflicting interferences between novel combinations and novel changes in intensity and duration of climate change‐related factors. Analysis of these contrasted situations emphasizes the need for future research on the diversity and robustness of plant signaling mechanisms under climate change conditions. This review analyses present knowledge on plant sensing and signaling mechanisms under conditions of climate change. Plant cells are endowed with environmental and stress sensors and internal signals that can act as potential mechanisms of climate change sensing. However, optimal functioning of existing sensors, optimal integration of additive constraints and signals, or stress memory processes can be hampered by conflicting interferences between climate change‐related factors. Analysis of these contrasted situations emphasizes the need for future research on the diversity and robustness of plant signaling mechanisms under climate change conditions. [ABSTRACT FROM AUTHOR]

Summary: The need to obtain the mechanical characteristics for analysis and understanding of the mechanical behaviour of historic buildings is highlighted. Destructive tests and non‐destructive tests are widely used for this purpose; however, they only provide a value associated with a specific instant. Structural health monitoring contributes to the monitoring of specific processes before, during, or after an intervention. Nevertheless, among the available sensors, there is a lack of devices for continuous monitoring of stress variations undergone by masonry structures. In response to this need, a new stress‐measurement device for structural monitoring of masonry structures has been developed. It has the aim of determining the initial stress in masonry structural element and providing continuous control of the evolution of the stress variation. The article describes the design of the device, as well as its implementation in a historic building. Moreover, an assessment is performed of the stress variations registered in comparison with the displacements recorded in the monitored areas, as well as the influence of the thermic fluctuations on these. A good relation was confirmed between these measurements. The results demonstrate that the designed device proved to be a useful tool for monitoring structural strengthening interventions. [ABSTRACT FROM AUTHOR]

Summary: In this study, an integrated structural health monitoring system was developed and applied to a masonry heritage building under rehabilitation, where diverse structural changes were made. The late 19th century building had over the years undergone significant deterioration, which brought about the appearance of serious pathological processes affecting the building's stability. In 2012, concerns over the severe cracking phenomena affecting the structure prompted the decision to monitor the structure and to undertake strengthening interventions. A global structural monitoring system was applied to the church to identify the occurrence of possible damage mechanisms and monitoring the intervention processes. The monitoring system was based on the integration of subsystems, which were implemented as and when necessary. Traditional sensors consisting of crackmeters, servo‐inclinometers, cable extension sensors, displacement transducers, wind vanes, and temperature sensors (thermo‐hygrometer and thermocouples) were installed on the building. Moreover, novel measuring approaches using stress sensors and pressure cells were used. Furthermore, manual monitoring elements were installed, which provided measurements for contrasting with those of the continuous sensors, as well as a greater number of monitoring points. Thus, the structural response was measured using 67 monitoring elements. The long‐term (5 years) monitoring results indicated that the interventions were carried out without the occurrence of any irregularity. A good relation was confirmed between the manual and continuous measurements. Moreover, the results have shown the capability of the proposed integrated system to evaluate the structural behaviour during all the phases of the interventions. [ABSTRACT FROM AUTHOR]

In this work a Cu pillar design that combines a stiff metal pedestal with a soft polymer as buffer layer has been integrated in a dedicated test vehicle to investigate the thermo mechanical stress induced during flip chip assembly. In-situ electrical measurements of dedicated stress sensors during a Bump Assisted BEOL Stability Indentation (BABSI) test were performed to assess the strength of the bump designs. Furthermore, the package induced stress was monitored in different regions of the test chips by measuring and comparing the I ON current of the stress sensors before and after packaging. By combining in-situ electrical measurements and finite element modeling it was possible to quantify the stress level induced in the Si die after packaging. Additionally, the package out of plane deformation has been measured after flip chip to laminate and after molding. The results show that the use of a stiff pedestal is very efficient to mitigate packaging induced stress. It has also been shown that the out of plane deformation is independent of the Cu pillar design. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) materials enable the transformation of mechanical stimuli into optical signals. However, current ML devices have limited luminescent programmability and mechanical tunability due to the relatively simple geometries as restricted by the conventional fabrication techniques. Here, we develop a strategy that is applicable for various types of zinc sulfide (ZnS)-based phosphors for allowing the fabrication of ML elastomer into complex 2D or 3D geometries with periodic cellular structures. We demonstrate that different cellular structures with tunable mechanical properties enable programmable structure-dependent ML behaviors including anisotropic and isotropic luminescence. We further exploit the quantitative structure-stress-luminescence relationship, which provides fundamental knowledge support for designing next-generation ML-based stress sensors and wearable devices. [Display omitted] • A granular mechanoluminescence elastomer network was developed for 3D printing. • Cellular structures with single- and multi-color were 3D printed at high resolution. • Programmable luminescence and mechanical properties were achieved. • Structure-stress-luminescence relationships were quantitatively studied. [ABSTRACT FROM AUTHOR]

Characterizing the mechanisms of plant sensitivity and reactivity to physicochemical cues related to abiotic stresses is of utmost importance for understanding plant-environment interactions, adaptations of the sessile lifestyle, and the evolutionary dynamics of plant species and populations. Moreover, plant communities are confronted with an environmental context of global change, involving climate changes, planetary pollutions of soils, waters and atmosphere, and additional anthropogenic changes. The mechanisms through which plants perceive abiotic stress stimuli and transduce stress perception into physiological responses constitute the primary line of interaction between the plant and the environment, and therefore between the plant and global changes. Understanding how plants perceive complex combinations of abiotic stress signals and transduce the resulting information into coordinated responses of abiotic stress tolerance is therefore essential for devising genetic, agricultural, and agroecological strategies that can ensure climate change resilience, global food security, and environmental protection. Discovery and characterization of sensing and signaling mechanisms of plant cells are usually carried out within the general framework of eukaryotic sensing and signal transduction. However, further progress depends on a close relationship between the conceptualization of sensing and signaling processes with adequate methodologies and techniques that encompass biochemical and biophysical approaches, cell biology, molecular biology, and genetics. The integration of subcellular and cellular analyses as well as the integration of in vitro and in vivo analyses are particularly important to evaluate the efficiency of sensing and signaling mechanisms in planta. Major progress has been made in the last 10-20 years with the caveat that cell-specific processes and in vivo processes still remain difficult to analyze and with the additional caveat that the range of plant models under study remains rather limited relatively to plant biodiversity and to the diversity of stress situations., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Thermo-mechanical stress is a major concern in the frame of 2.5D integration. Passive stress sensors were integrated in a silicon interposer test vehicle to quantify stress at critical locations. The sensors were integrated in a rosette-shape consisting of eight oriented copper serpentines acting like strain gauges. This innovative design allows the calculation of a partial stress tensor, including three planar and one out-of-plane components. Electrical measurements at wafer level, combined with FIB/SEM cross-sections, revealed a strong impact of elaboration processes on the structures electrical characteristics. Numerical simulations using finite element analysis were built to evaluate the sensitivity of copper serpentines to mechanical stress. Finally a dedicated four-point bending tool coupled with a four-terminal resistance measurement setup was fabricated to experimentally extract the values of sensors sensitivity factors. Preliminary results depicted in this paper highlight a sensitivity to stress of distinctly oriented resistors. Several identified sources of data dispersion are inherent to the present measurement configuration. Added-value and limitations of such sensors were underlined, and recommendations regarding the testing strategy were drawn to allow a reliable estimation of the stress fields. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Highlights: [•] Proposed a computational stress signal predictor system to estimate a stress signal. [•] System based on support vector machine, genetic algorithm and neural network. [•] An experiment was conducted to acquire real-world stress data. [•] Features extracted from the stress data were provided as input to the system. [•] The stress signal was most similar to a hyperbolic tangent curve. [Copyright &y& Elsevier]