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Traditional systems for indoor pressure sensing and human activity recognition (HAR) rely on costly, high-resolution mats and computationally intensive neural network-based (NN-based) models that are prone to noise. In contrast, we design a cost-effective and noise-resilient pressure mat system for HAR, leveraging Velostat for intelligent pressure sensing and a novel hyperdimensional computing (HDC) classifier that is lightweight and highly noise resilient. To measure the performance of our system, we collected two datasets, capturing the static and continuous nature of human movements. Our HDC-based classification algorithm shows an accuracy of 93.19%, improving the accuracy by 9.47% over state-of-the-art CNNs, along with an 85% reduction in energy consumption. We propose a new HDC noise-resilient algorithm and analyze the performance of our proposed method in the presence of three different kinds of noise, including memory and communication, input, and sensor noise. Our system is more resilient across all three noise types. Specifically, in the presence of Gaussian noise, we achieve an accuracy of 92.15% (97.51% for static data), representing a 13.19% (8.77%) improvement compared to state-of-the-art CNNs.

The integration of pressure quantification and visualization enhances pressure perception, accuracy, and efficiency. Current solutions require improvements in quantization accuracy, structural simplicity, and integration. We proposed a novel photonic skin comprising a 3 × 1 flexible optical fiber combiner, integrating red, green, and blue light emitting diode (LED) chips through three flexible optical fibers. Under pressure, changes in the optical fibers' transmission loss alter the output light intensity ratio, thus inducing a color shift at the combiner's output. This visible change can be precisely quantified using a color sensor chip. Performance metrics include sensing range up to 33N, sensitivity between 0.04 and 0.24 dB N−1, detection limit below 0.08 N, response time of 500 ms, recovery time of 400 ms, and durability exceeding 2000 cycles. A compact flexible circuit board manages light source driving, data acquisition, and wireless communication, forming a wearable photonic skin system. This system enables visual recognition and quantitative measurement of pressure across diverse scenarios, including different tactile modes, multi‐position pressure, finger bending, and neck movement. For oral occlusion force detection, the spatial separation of the sensing and visualization areas enables the system to simultaneously provide accurate measurements and intuitive visual assessment. [ABSTRACT FROM AUTHOR]

Optical sensing technology based on mechanoluminescent (ML) materials offers advantages such as rapid response, real‐time monitoring, visual signal output, and multi‐functional sensing, making it promising for various applications. However, traditional sensing techniques based on the absolute intensity of ML suffer from issues of low accuracy and large errors, which have a significant impact on the reliability and visual effectiveness of the sensor. To address these problems, this study employs a ratiometric ML pressure sensing method. By utilizing the primary color recognition of human cone cells, transition metal ion Mn2+ and rare earth ion Tb3+ are selected as luminescent centers. The rich intermediate colors ensure a wide range of colors that are easily distinguishable by the human eye. Through studies involving mechanical stimulation and similar high‐energy radiation, it is confirmed that the differences in sensitivity between rare earth ions and transition metal ions, as well as the contributions of shallow trap states, are the reasons for the dynamic changes in the ratiometric ML intensity. Finally, a conceptual application of pressure sensing is realized by combining homogeneous gas compression with pipeline monitoring for dynamic visualization, self‐referencing, and high‐precision mechanical sensing. [ABSTRACT FROM AUTHOR]

High‐sensitivity flexible wireless passive sensors with multiple parameters sensing capability are highly demanded for industrial production, structural health monitoring, and medical care. In this study, a microstructure‐enhanced temperature and pressure dual‐mode inductance capacitance (LC) sensor is developed with a particle swarm optimization‐back propagation (PSO‐BP) algorithm for simultaneous measurement of temperature and pressure. In the device, two interdigital electrodes connected at different parts of an inductor is used to realize dual‐mode measurement of pressure and temperature, with reduced volume and cost of the device as well as avoided interaction of the superimposed inductance. The sandpaper‐molded polydimethylsiloxane microstructures are employed to enhance the device sensitivity, with six and three times of improvement in temperature and pressure sensitivity, respectively. A PSO‐BP neural network suitable for regression analysis of low dimensional small sample data is constructed to achieve the simultaneous measurement of pressure and temperature with an accuracy up to 94%. Furthermore, investigations have proved the promising applications of the dual‐mode LC sensor in health monitoring of lithium‐ion batteries and detection of plantar pressure for medical care. [ABSTRACT FROM AUTHOR]

Multifunctional integration is a pivotal aspect in the development of flexible sensors that facilitate augmented interaction with the physical environment. However, contemporary multifunctional flexible sensors face challenges arising from their complex structures and high costs. Therefore, polydimethylsiloxane (PDMS) /liquid metal (LM) films with a hierarchical structure prepared via the gravity‐induced deposition of LM are applied to multifunctional flexible sensors. PDMS/LM films exhibit remarkable flexibility and function as flexible electrodes for pressure sensors as well as a single‐electrode mode triboelectric nanogenerator (TENG). The porous PDMS/carbon nanotube (CNT) dielectric with an array structure is developed for pressure sensing, showing commendable sensitivity (0.671 kPa−1) even under low pressures (0–17 kPa). Compared with solid and porous dielectrics, its sensitivity is improved over the entire pressure range. The sensor achieves a response time of ≈80 ms and demonstrates exceptional stability. Furthermore, when the PDMS/LM film with a hierarchical structure functions as a TENG, it can serve as a self‐powered sensor for measuring dynamic forces and aid in material recognition with the assistance of capacitive pressure sensing. This study provides a new perspective on the simplified design and integration of multifunctional flexible sensors. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) non‐layered materials, along with their unique surface properties, offer intriguing prospects for sensing applications. Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non‐layered devices, such as high frequency, high tunability, and large dynamic range, which could lead to new types of high performance nanosensors. Here, we demonstrate 2D non‐layered nanomechanical resonant sensors based on β‐In2S3, where the devices exhibit robust nanomechanical vibrations up to the very high frequency (VHF) band. We show that such device can operate as pressure sensor with broad range (from 10−3 Torr to atmospheric pressure), high linearity (with a nonlinearity factor as low as 0.0071), and fast response (with an intrinsic response time less than 1 μs). We further unveil the frequency scaling law in these β‐In2S3 nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal. Our work paves the way towards future wafer‐scale design and integrated sensors based on 2D non‐layered materials. [ABSTRACT FROM AUTHOR]

Fiber Bragg Grating (FBG) pressure sensor has the advantages of underwater passive, corrosion resistance, light weight, low cost and anti-electromagnetic interference, which has been widely used. This paper first briefly introduces the basic principle of FBG pressure sensing. It then summarizes the development status of FBG writing technology, pressure sensing and sensitizing technology, and temperature compensation technology. Next, it summarizes the application progress of FBG pressure sensor in the fields of ocean depth, lake level measurement, oil and gas pipeline pressure measurement, and rock and soil pressure monitoring in recent years. Finally, the FBG pressure sensing technology is prospected.

[Display omitted] • Biomass-based carbon aerogels with low volume shrinkage were fabricated. • Zn (II) crosslinking significantly improved the carbon retention rate during carbonization. • High compressive strength, superelasticity and excellent fatigue resistance were achieved. • The piezoresistive sensor exhibited high sensitivity, fast response and good repeatability. • The assembled wearable sensor was successfully applied for detecting human motions. Elastic carbon aerogels have promising applications in the field of wearable sensors. Herein, a new strategy for preparing carbon aerogels with excellent compressive strength and strain, shape recovery, and fatigue resistance was proposed based on the structure design and carbonization optimization of nanocellulose-based precursor aerogels. By the combination of directional freezing and zinc ion cross-linking, bacterial cellulose (BC)/alginate (SA) composite aerogels with high elasticity and compressive strength were first achieved. The existance of zinc ions also significantly improved the carbon retention rate and inhibited structural shrinkage, thus making the carbon aerogels retain ultra-high elasticity and fatigue resistance after compression. Moreover, the carbon aerogel possessed excellent piezoresistive pressure sensing performance with a wide detection range of 0–7.8 kPa, high sensitivity of 11.04 kpa-1, low detection limit (2 % strain), fast response (112 ms), and good durability (over 1,000 cycles). Based on these excellent properties, the carbon aerogel pressure sensors were further successfully used for human motion monitoring, from joint motion to and speech recognition. [ABSTRACT FROM AUTHOR]

AlB4O6N, Al0.97Cr0.03B4O6N, and Al0.83Cr0.17B4O6N are the first representatives of the recently established structure‐family of oxonitridoborates containing Al3+. These compounds are isotypic to CrB4O6N and are synthesized in a multi‐anvil press under high‐pressure/high‐temperature conditions of 7.0 GPa/1350 °C. Structural refinement by single‐crystal X‐ray diffraction shows that they crystallize in the space group P63mc (no. 186) with two formula units per cell. Detailed characterization including high‐temperature X‐ray powder diffraction (HT‐XRD), electron probe microanalysis (EPMA), measurements of second harmonic generation (SHG), hardness, photoluminescence properties, vibrational spectroscopy, and band structure calculations reveal intriguing physicochemical properties that strongly resemble the famous material ruby. [ABSTRACT FROM AUTHOR]

There is an extensive need for surface sensors for applications such as tactile sensing for robotics, damage and strain detection for structural health monitoring and leak detection for buried structures. One type of surface sensor is electrical impedance tomography (EIT)-based sensing skins, which use electrically conductive coatings applied on the object's surface to monitor physical or chemical phenomena on the surface. In this article, we propose a sensing skin with two electrically coupled layers separated by an insulator. Based on electrical measurements, the spatial distribution of the electrical coupling between the layers is estimated. This coupling is sensitive to both the pressure distribution on the surface and water entering between the layers through a leak. We present simulations and experimental studies to evaluate the feasibility of the proposed method for pressure sensing and leak detection. The results support the feasibility of the proposed method for both of these applications. [ABSTRACT FROM AUTHOR]

Copyright of Automotive Digest is the property of Automotive Digest Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Woodwork is involved in a variety of interactions with humans through physical contact, which may reveal valuable information if the tactile data can be unnoticeably extracted. In this work, an intelligent iontronic wood (iWood) device, along with its seamlessly integrated architecture into the woodwork, enabled by the iontronic sensing principle, is implemented. Notably, the tactile sensing structure is generated at the iontronic interface between ionic and conductive woods. In particular, the ionic wood is established by infusing an ionic liquid into the wood, followed by immobilizing it via chemical bonding, presenting both prominent ionic conductivity and excellent stability under pressure. By formatting the woods into identical strips, the high‐density tactile sensing array can be simply formed by a braiding process for a scalable interwoven structure. As a result, the iWood device has offered a high sensitivity over a broad detection of 0.5 MPa and an array of 40 × 90 units covering an area up to 3600 cm2. The iWood device is showcased as an interactive human interface, demonstrating its potential as a smart desktop capable of gesture and object recognition, a health‐tracking chair for real‐time ballistocardiograph monitoring, and an embedded intelligent floor for weight management and gait analysis. [ABSTRACT FROM AUTHOR]

Dynamically responsive materials with chromotropic properties have received increasing attention in flexible pressure sensing due to their intuitive nature in the information transfer process. Here, inspired by the biological dynamic regulation of structural color in nature, a robust biomimetic mechanochromic photonic ionogel is ingeniously constructed. The photonic ionogel undergoes continuous and regular structural color changes under compression and outputs stable optical signals, possessing excellent linear pressure responsiveness and stability. The photonic ionogel exhibits sensitive changes in structural color and reflection wavelength via adjusting the lattice spacing of the 3D photonic crystal (mechanochromic sensitivity: 2.21 nm per %, Δλ > 150 nm). Furthermore, the good compatibility between ionogel and PC microspheres endows photonic ionogel with good linear pressure responsiveness (R2 ≈ 0.984). Meanwhile, ionic liquid (IL) and the covalent cross-linking network of robust polyurethane elastomer provide photonic ionogel with a wide temperature tolerance range (Tg ≈ −49.5 °C, initial decomposition temperature of 301 °C) and mechanical durability (5000 cycles of compression). This work demonstrates promising applications not only in flexible pressure sensing but also in advanced visual interaction devices. [ABSTRACT FROM AUTHOR]

Piezoelectric nanogenerators (PENGs), the current pathway to sustainable energy harvesting, are mostly comprised of bulk oxide ceramics which are toxic, rigid, and costly to synthesize. A suitable alternative to them is flexible polar polymers like polyvinylidene fluoride (PVDF), but stabilizing its polar phase is also a daunting task. all these aforementioned issues by employing a biocompatible have been solved, above‐room‐temperature (Tc > 390 K) ferroelectric discrete molecular complex [Cu(L‐His)(bpy)]ClO4.1.5H2O (Cu‐FE) which is not only suitable for piezoelectric energy harvesting due to its large values of piezoelectric co‐efficient (d33 = 17 pm V−1) but also is capable of imparting polar β‐phase in PVDF via hydrogen bonding interactions under mild condition (60 °C). Among the PENG devices prepared with the composite films of PVDF and various weight % (w/V) compositions of Cu‐FE, the highest output voltage of 8 V (peak to peak) has been obtained, a power density of 4 µW cm−2, and an output current of 3 µA from the 1 wt.% composite film. The fabricated PENG device also exhibits swift capacitor charging in 40 s, and acts as an excellent pressure sensor, with exceptional sensitivity to low pressures (7 kPa), giving an output of 0.4 V. [ABSTRACT FROM AUTHOR]

Copyright of Study on Optical Communications / Guangtongxin Yanjiu is the property of Study on Optical Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In addressing the broad spectrum of applications for optical pressure sensors, their predominant drawback lies in their limited sensitivity to pressure fluctuations. To overcome these constraints, this study introduces a luminescent manometer harnessing the emission properties of Cr3+ ions in Li3Sc2(PO4)3, operational in three distinct reading modes: spectral shift, ratiometric, and lifetime‐based. Notably, the conducted research establishes this luminescent manometer as the most sensitive reported to date in both spectra shift (λ/dp = 23.9 nm/GPa) and lifetime‐based (SR = 93.56%/GPa) modes. A departure from conventional lifetime‐based luminescent pressure gauges, Li3Sc2(PO4)3:Cr3+ exhibits a prolongation of lifetime of the 4T2 state correlated with increasing pressure. The advantages extend beyond sensitivity, encompassing a three‐fold surge in emission intensity with pressure escalation from ambient to 3 GPa, coupled with minimal susceptibility to temperature‐induced fluctuations. Unquestionably, Li3Sc2(PO4)3:Cr3+ showcases remarkable manometric performance, validating its significant application potential in diverse scenarios within the realm of optical pressure sensors. [ABSTRACT FROM AUTHOR]

Stem expansion and contraction are closely related to the plant water status. It is of great significance to real-time monitor the stem expansion and contraction, in order to improve the utilization rate of agricultural water resources in irrigation systems. Therefore, the sensors have been mainly used to monitor the expansion and contraction of plant stems at present. The linear micro-displacement can be measured to assess the plant water status. However, it is still limited to the high cost and inconvenient installation. In this study, a flexible and wearable sensor was designed and developed using the piezoresistive effect. A flexible pressure electrode was used as the sensing element to monitor the pressure variation, which was attached to the surface of plant stems. Different from the linear micro-displacement sensor, the developed sensor was used to assess the pressure variation caused by the expansion and contraction of the stem. The pressure signal detection and data collection were also designed to convert the pressure into electrical signals for storage. A series of experiments were conducted to evaluate the performance of the pressure sensor. Firstly, the performance test and sensor calibration were conducted under laboratory conditions. Then, the pressure sensor was installed on a tomato stem in a greenhouse, in order to observe the pressure variation. A comparison was made with the linear micro-displacement sensor. Finally, the variations in the expansion and contraction of tomato stems were observed under sufficient irrigation and water deficit using the two types of sensors. The results show that the average relative change rate of the stability test for flexible pressure sensors was 0.109%; There was negligible output variation caused by bending; The determination coefficient of calibration was greater than 0.99, and the most suitable working range was 2-100 kPa; The determination coefficient of the measurements between the two types of sensors was 0.955 1, compared with the linear micro displacement sensors. The greenhouse experiments show that the determination coefficients of the measurements using the two types of sensors were 0.767 2 and 0.851 9, respectively, for full irrigation and deficient irrigation. The flexible and wearable pressure sensor can be expected to monitor the variations in the expansion and contraction of tomato stems. The water deficit stress of the tomato can also be diagnosed as well. The pressure sensor achieved better performance during the experiment, such as the low cost and easy installation, compared with the linear micro-displacement sensors. [ABSTRACT FROM AUTHOR]

Multifunctional sensors have played a crucial role in constructing high-integration electronic networks. Most of the current multifunctional sensors rely on multiple materials to simultaneously detect different physical stimuli. Here, we demonstrate the large piezo-pyroelectric effect in ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals for simultaneous pressure and temperature sensing. The outstanding piezoelectric and pyroelectric properties of PMN-PT result in rapid response speed and high sensitivity, with values of 46 ms and 28.4 nA kPa−1 for pressure sensing, and 1.98 s and 94.66 nC °C−1 for temperature detection, respectively. By leveraging the distinct differences in the response speed of piezoelectric and pyroelectric responses, the piezo-pyroelectric effect of PMN-PT can effectively detect pressure and temperature from mixed-force thermal stimuli, which enables a robotic hand for stimuli classification. With appealing multifunctionality, fast speed, high sensitivity, and compact structure, the proposed self-powered bimodal sensor therefore holds significant potential for high-performance artificial perception. [ABSTRACT FROM AUTHOR]

Abstract Two‐dimensional (2D) non‐layered materials, along with their unique surface properties, offer intriguing prospects for sensing applications. Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non‐layered devices, such as high frequency, high tunability, and large dynamic range, which could lead to new types of high performance nanosensors. Here, we demonstrate 2D non‐layered nanomechanical resonant sensors based on β‐In2S3, where the devices exhibit robust nanomechanical vibrations up to the very high frequency (VHF) band. We show that such device can operate as pressure sensor with broad range (from 10−3 Torr to atmospheric pressure), high linearity (with a nonlinearity factor as low as 0.0071), and fast response (with an intrinsic response time less than 1 μs). We further unveil the frequency scaling law in these β‐In2S3 nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal. Our work paves the way towards future wafer‐scale design and integrated sensors based on 2D non‐layered materials.

Arterial Vascular smooth muscle cells (VSMCs) play a central role in the onset and progression of atherosclerosis. Upon exposure to pathological stimuli, they can take on alternative phenotypes that, among others, have been described as macrophage like, or foam cells. VSMC foam cells make up >50% of all arterial foam cells and have been suggested to retain an even higher proportion of the cell stored lipid droplets, further leading to apoptosis, secondary necrosis, and an inflammatory response. However, the mechanism of VSMC foam cell formation is still unclear. Here, it is identified that mechanical stimulation through hypertensive pressure alone is sufficient for the phenotypic switch. Hyperspectral stimulated Raman scattering imaging demonstrates rapid lipid droplet formation and changes to lipid metabolism and changes are confirmed in ABCA1, KLF4, LDLR, and CD68 expression, cell proliferation, and migration. Further, a mechanosignaling route is identified involving Piezo1, phospholipid, and arachidonic acid signaling, as well as epigenetic regulation, whereby CUT&Tag epigenomic analysis confirms changes in the cells (lipid) metabolism and atherosclerotic pathways. Overall, the results show for the first time that VSMC foam cell formation can be triggered by mechanical stimulation alone, suggesting modulation of mechanosignaling can be harnessed as potential therapeutic strategy. [ABSTRACT FROM AUTHOR]

Beta gallium oxide (β‐Ga2O3) has emerged as a highly promising semiconductor material with an ultrawide bandgap ranging from 4.5 to 4.9 eV for future applications in power electronics, optoelectronics, as well as gas and ultraviolet (UV) radiation sensors. Here, surface adsorption and air damping behavior of doubly clamped β‐Ga2O3 nanomechanical resonators are probed and systemically studied by measuring the resonance characteristics under different gas and pressure conditions. High responsivities of resonance to pressure are obtained by heating the devices up to 300 °C to induce an accelerated adsorption–desorption process. The initial surface conditions of the β‐Ga2O3 thin film play important roles in affecting the resonant behavior. UV ozone treatment proves effective in altering the initial surface conditions of β‐Ga2O3 nanosheets by eliminating physisorbed contaminants and filling oxygen vacancy defects residing on the surface, resulting in a consequential and discernible modification of the resonance behavior of β‐Ga2O3 nanomechanical resonators. The surface adsorption and desorption processes in β‐Ga2O3 demonstrate clear reversibility by exposing the UV treated β‐Ga2O3 to air. This study attains first‐hand information on how the surface conditions of β‐Ga2O3 affect its mechanical properties, and helps guide future development of transducers via β‐Ga2O3 nanoelectromechanical systems (NEMS) for pressure sensing applications, especially in harsh environments. [ABSTRACT FROM AUTHOR]

Aerogels with regularly porous structure and uniformly distributed conductive networks have received extensive attention in wearable electronic sensors, electromagnetic shielding, and so on. However, the poor mechanical properties of the emerging nanofibers-based aerogels are limited in practical applications. In this work, we developed a synchronous deprotonation-protonation method in the KOH/dimethyl sulfoxide (DMSO) system at room temperature for achieving chitin cross-linked aramid nanofibers (CANFs) rather than chitin nanofibers (ChNFs) and aramid nanofibers (ANFs) separately by using chitin and aramid pulp as raw materials. After freeze-drying process, the cross-linked chitin/aramid nanofibers (CA) aerogel exhibited the synergetic properties of ChNF and ANF by the dual-nanofiber compensation strategy. The mechanical stress of CA aerogel was 170 kPa at 80% compressive strain, increased by 750% compared with pure ChNF aerogel. Similarly, the compressibility of CA aerogel was somewhat improved compared to ANF aerogel. The enhancement verified that the crosslinking reaction between ANF and ChNF during the synchronous deprotonation process was formed. Afterwards, the conductive aerogels with uniform porous structure (CA-M) were successfully obtained by vacuum impregnating CA aerogels in Ti3C2Tx MXene solution, displaying low thermal conductivity (0.01 W/(m·K)), high electromagnetic interference (EMI) shielding effectiveness (SE) (75 dB), flame retardant, and heat insulation. Meanwhile, the as-obtained CA-M aerogels were also applied as a pressure sensor with excellent compression cycle stability and superior human motion monitoring capabilities. As a result, the dual-nanofiber based conductive aerogels have great potentials in flexible/wearable electronics, EMI shielding, flame retardant, and heat insulation. [ABSTRACT FROM AUTHOR]

Flexible electronic skin (e-skin) for mobile health applications urgently requires wearable pressure-gas sensors, which can be used for body motion detection and identification of environmental gas targets. However, applying pressure-gas sensors to e-skin has always faced challenges of high sensitivity, wide detection range, and high stability. Herein, a novel multifunctional pressure-gas sensor was proposed that 2D reduced graphene oxide (rGO) with 1D copper nanowires (CuNWs) and silver nanowires (AgNWs) form 3D porous composite aerogels by self-assembly and in situ oxidation CuNWs convert to Cu x O nanowires (Cu x ONWs), which ensures efficient electron transfer and sufficient gas adsorption sites. Furthermore, the polydimethylsiloxane (PDMS) layer dramatically improved the electro-mechanical properties of the sensing elastomer. The rGO-Cu x ONW-AgNW/PDMS (GCOAP) sensing elastomer realizes bi-directional resistive response of pressure (falling) and gas (rising), and is capable of fast response (66 ms) to large pressures (1600 kPa) with high sensitivity (1.405 kPa−1) and specific identification of hazardous NH 3 gas at room temperature. [ABSTRACT FROM AUTHOR]

In this study, we developed a novel wireless, passive pressure-sensing method functional at cryogenic temperatures (−196 °C). The currently used pressure sensors are inconvenient and complicated in cryogenic environments for their weak low-temperature tolerances and long wires for power supply and data transmission. We propose a novel pressure-sensing method for cryogenic applications by only using low-temperature-tolerant passive devices. By innovatively integrating a magnetoresistor (MR) on a backscattering antenna, the pressure inside a cryogenic environment is transferred to a wirelessly obtainable return loss. Wireless passive measurement is thus achieved using a backscattering method. In the measurement, the pressure causes a relative displacement between the MR and a magnet. The MR's resistance changes with the varied magnetic field, thus modulating the antenna's return loss. The experimental results indicate that our fabricated sensor successfully identified different pressures, with high sensitivities of 4.3 dB/MPa at room temperature (24 °C) and 1.3 dB/MPa at cryogenic temperature (−196 °C). Additionally, our method allows for simultaneous wireless readings of multi sensors via a single reading device by separating the frequency band of each sensor. Our method performs low-cost, simple, robust, passive, and wireless pressure measurement at −196 °C; thus, it is desirable for cryogenic applications. [ABSTRACT FROM AUTHOR]

During vapour phase reflow soldering used in electronics manufacturing, the process control of ovens is usually based on temperature measurements, which can be insufficient due to the saturation differences in the temperature and the vapour concentration. Therefore, the ovens use extended cycle times for process identification to ensure the proper formation of solder joints. This study offers a solution to eliminate the idle time by investigating the hydrostatic pressure conditions in the process zone. A pressure measurement system was developed for vapour phase soldering ovens which can monitor the vapour pressure changes by a gauge-type pressure sensor with fused temperature measurement. It works as an IoT-enabled node for data logging and subsequent control. The fusion of the hydrostatic pressure values with the temperature values allowed us to identify and reduce the idle time by approximately 60 s, which is 15–20% of the total soldering cycle time. This increases the oven's yield by 15–20%, reduces the system's power consumption by 15–20%, and reduces time above liquidus of the solder by ∼35%. The presented method could enhance the more sustainable electronics production according to the Sustainability Development and could improve the quality and reliability of the lead-free solder joints.

In this paper, a photonic skin sensor based on a balloon-shaped optical fiber structure cascading a Fiber Bragg Grating (FBG) is proposed, which can simultaneously sense pressure and temperature. When the photonic skin feels pressure, the built-in polymer micro-cap is squeezed, causing a change in the radius of the balloon-shaped structure. At the same time, the capillary-enclosed FBG can be used for temperature compensation. The pressure sensitivity of the photon skin sensor can reach 6.556 nm/mN in the range of 0-0.5 mN and the temperature sensitivity can reach -0.192 nm/°C in the range of 30-50 °C. The demodulation of the dual parameter matrix shows that the error rates of pressure and temperature measurements are less than 0.5% and 2.01%, respectively. On this basis, the sensor is applied to robotic arm-assisted puncture experiment detection, and the five states of the puncture process are analyzed. Based on the backpropagation (BP) neural network for repeated training, the results show that its accuracy remains at 98.7%, indicating that the sensor has good robustness. The development of this sensor shows application potential in the field of robotic intelligent skin in the future.

Designing ultra‐light, green, and flexible films for efficient electromagnetic interference (EMI) shielding is crucial yet challenging. Herein, laminated Ti3C2Tx MXene nanosheets are prepared and impregnated into a delignified wood matrix to fabricate composite films. Through a facile drop‐casting and densification strategy, highly aligned cellulose fibers are used for regulating the stacking behavior of MXenes, and the MXenes are encapsulated and attached tightly to the cellulose chains through hydrogen bonds. A high MXene loading up to 32.5 wt.% can be realized, and the resultant MXene/wood film exhibits a tensile strength of 260.7 MPa. The EMI shielding effectiveness is calculated to be 55.5 dB (X‐band, 8.2–12.4 GHz), with a normalized surface‐specific shielding effectiveness of 2673.4 B cm2 g−1. Moreover, the superior electrical conductivity and structural robustness of the composite film give it pressure‐sensing properties and show high sensitivity for monitoring diverse human physiological movements. [ABSTRACT FROM AUTHOR]

Abstract Arterial Vascular smooth muscle cells (VSMCs) play a central role in the onset and progression of atherosclerosis. Upon exposure to pathological stimuli, they can take on alternative phenotypes that, among others, have been described as macrophage like, or foam cells. VSMC foam cells make up >50% of all arterial foam cells and have been suggested to retain an even higher proportion of the cell stored lipid droplets, further leading to apoptosis, secondary necrosis, and an inflammatory response. However, the mechanism of VSMC foam cell formation is still unclear. Here, it is identified that mechanical stimulation through hypertensive pressure alone is sufficient for the phenotypic switch. Hyperspectral stimulated Raman scattering imaging demonstrates rapid lipid droplet formation and changes to lipid metabolism and changes are confirmed in ABCA1, KLF4, LDLR, and CD68 expression, cell proliferation, and migration. Further, a mechanosignaling route is identified involving Piezo1, phospholipid, and arachidonic acid signaling, as well as epigenetic regulation, whereby CUT&Tag epigenomic analysis confirms changes in the cells (lipid) metabolism and atherosclerotic pathways. Overall, the results show for the first time that VSMC foam cell formation can be triggered by mechanical stimulation alone, suggesting modulation of mechanosignaling can be harnessed as potential therapeutic strategy.

There is an extensive need for surface sensors for applications such as tactile sensing for robotics, damage and strain detection for structural health monitoring and leak detection for buried structures. One type of surface sensor is electrical impedance tomography (EIT)-based sensing skins, which use electrically conductive coatings applied on the object’s surface to monitor physical or chemical phenomena on the surface. In this article, we propose a sensing skin with two electrically coupled layers separated by an insulator. Based on electrical measurements, the spatial distribution of the electrical coupling between the layers is estimated. This coupling is sensitive to both the pressure distribution on the surface and water entering between the layers through a leak. We present simulations and experimental studies to evaluate the feasibility of the proposed method for pressure sensing and leak detection. The results support the feasibility of the proposed method for both of these applications.

Abstract Mechanical forces control the function of organisms and mediate the interaction between biological systems and their environments. Knowledge of these forces will increase the understanding of biological processes and can support the development of novel diagnostic and therapeutic procedures. Although techniques like atomic force microscopy and droplet insertion method allow measuring forces over a broad range of values, they are invasive and lack versatility. A promising way to overcome these hurdles is luminescent nanomanometry. Quantum dots (QDs) specifically have optical properties that depend on their size because of the quantum confinement, which makes them responsive to applied forces. Yet, a fine understanding of how fundamental parameters affect the response to applied stress is required before a QD family can be credibly proposed as luminescent nanomanometers. Here, a thorough study is conducted on how size and stoichiometry affect the nanomanometry performance of CuInS2 QDs. The studied QDs feature pressure‐dependent photoluminescence in the red/near‐infrared range, which can enable the measurement of mechanical forces in the range of physiological relevance in a remote and minimally invasive way. It is shown that tuning size and stoichiometry can simultaneously enhance the CuInS2 QDs’ brightness and response to applied pressure, thus providing guidelines for better luminescent nanomanometers.

In this work, a portable venturi tube capable of measuring bidirectional respiratory flow is developed and correlated the measurements to pulmonary function. Pressure signals are transduced using flexible and compressible capacitive foam sensors embedded into the wall of the device. In this configuration, the sensors are able to provide differential pressure readings, from which the airflow rate passing through the tube could be extrapolated. Utilizing the venturi effect, the geometry of the spirometer tube is designed through finite element analysis to measure respiratory airflow during inhalation and exhalation. The device tube is 3D‐printed and used to measure tidal breathing and deep breathing, along with peak expiratory flow rates, on a healthy individual. This spirometer design allows for easy‐to‐use point‐of‐care diagnoses and has the potential to improve the care of respiratory illnesses. [ABSTRACT FROM AUTHOR]

Multifunctional sensors have played a crucial role in constructing high-integration electronic networks. Most of the current multifunctional sensors rely on multiple materials to simultaneously detect different physical stimuli. Here, we demonstrate the large piezo-pyroelectric effect in ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals for simultaneous pressure and temperature sensing. The outstanding piezoelectric and pyroelectric properties of PMN-PT result in rapid response speed and high sensitivity, with values of 46 ms and 28.4 nA kPa−1 for pressure sensing, and 1.98 s and 94.66 nC °C−1 for temperature detection, respectively. By leveraging the distinct differences in the response speed of piezoelectric and pyroelectric responses, the piezo-pyroelectric effect of PMN-PT can effectively detect pressure and temperature from mixed-force thermal stimuli, which enables a robotic hand for stimuli classification. With appealing multifunctionality, fast speed, high sensitivity, and compact structure, the proposed self-powered bimodal sensor therefore holds significant potential for high-performance artificial perception.

Traditional systems for indoor pressure sensing and human activity recognition (HAR) rely on costly, high-resolution mats and computationally intensive neural network-based (NN-based) models that are prone to noise. In contrast, we design a cost-effective and noise-resilient pressure mat system for HAR, leveraging Velostat for intelligent pressure sensing and a novel hyperdimensional computing (HDC) classifier that is lightweight and highly noise resilient. To measure the performance of our system, we collected two datasets, capturing the static and continuous nature of human movements. Our HDC-based classification algorithm shows an accuracy of 93.19%, improving the accuracy by 9.47% over state-of-the-art CNNs, along with an 85% reduction in energy consumption. We propose a new HDC noise-resilient algorithm and analyze the performance of our proposed method in the presence of three different kinds of noise, including memory and communication, input, and sensor noise. Our system is more resilient across all three noise types. Specifically, in the presence of Gaussian noise, we achieve an accuracy of 92.15% (97.51% for static data), representing a 13.19% (8.77%) improvement compared to state-of-the-art CNNs.

The practical applications of hydrogel-based sensors are limited by their low mechanical strength, insufficient sensitivity and machining difficulties caused by electrically conductive fillers. It is of great practical importance for facile preparation of hydrogel sensor combined with excellent mechanical properties and conductive sensitivity. In this work, a series of ion-conductive hybrid hydrogels based on in-situ polymerized polyacrylamide with double and triple network structures have been fabricated via both chemical and physical cross-linking. The triple network structured hydrogels achieve the tensile strength of 2.105 MPa and compression strength of 57.56 MPa, which are much higher than those of hydrogels with double network due to the established energy dissipation gradient. The reversible non-covalent cross-linking in the network also leads a relatively fast recovery in tensile cycle tests and double compression tests, enabling the excellent stability of strain sensing in the durability test. The hydrogels show the tensile resistance sensitivity factor of 0.9352 at 0–120% strain and a high pressure sensitivity factor of 5.134 kPa−1 with the pressure ranged from 0 to 6 kPa. The hydrogels are also assembled as flexible sensors for human motion monitoring, and the signals of motions can be distinguished by different resistance variation values and certain curve shape, showing the potential of applications on flexible device and human-machine interface.

Polydimethylsiloxane (PDMS) based soft polymer optical fibers (POFs) have recently demonstrated their intriguing potential for different sensing applications like strain or temperature sensing. Recent studies have elaborated on the sensing capability of PDMS POFs, yet the in-depth analysis of the processing-property relationship of PDMS POFs remains unexplored. A straightforward processing strategy was developed for core only PDMS POFs and PDMS/THV (terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride) core/clad POFs. The optimization of chemical formulations and process parameters such as curing temperature and curing time provided the development of POFs with tailored mechanical and optical properties. The tensile modulus of the moulded PDMS POFs could be tuned in the range of 0.2–3.0 MPa, with attenuations as low as 0.11 dB/cm in the near infrared region (NIR). Furthermore, the load and pressure sensing capability of the PDMS POFs was demonstrated with sensitivity to loads as low as 0.1 N and highly accurate pressure sensing up to 300 kPa. The systematic approach presented in this study enables the processing of elastic PDMS POFs with tunable mechanical and optical properties, which can be tailored to suitable sensing applications in the field of healthcare monitoring, biomedicine, and soft robotics.

Sensing fabrics have received great attention due to various applications in medical area, healthcare, and smart clothes. However, there are very few studies on sensing fabrics that can be used to monitor the pressure of compression garments. In this study, a pressure exerting and sensing fabric is fabricated by interweaving highly sensitive yarn sensor into woven fabric using industrial‐scale weaving technology. By using a new method for measuring the pressure sensing capabilities under external stresses from a curved surface, effects of fabric structure and operation mode on the pressure and electromechanical properties are evaluated. New fabric structures are proposed to deliberately arrange the yarn sensing elements in a less‐ or even non‐binding form within the fabric for good elasticity and sensing properties. Arising from the appropriate material selection and structure feature, the sensing fabric realizes a suitable and stable amount of induced pressure as well as very low stress relaxation. Consequently, the sensing fabric with sateen structure demonstrates very good pressure sensing performance with sensitivity of 1.22 kPa−1, low hysteresis error of 8.06%, and linearity of 0.98 in the desired pressure range from 0.58 to 3.83 kPa. Furthermore, the fabric exhibits excellent stability over 4500 pressing cycles. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of the correlation between the emotional state of a person and the posture of his or her body in the sitting position. In order to carry out the study, we developed the first version of the hardware-software system based on a posturometric armchair, allowing the characteristics of the posture of a sitting person to be evaluated using strain gauges. Using this system, we revealed the correlation between sensor readings and human emotional states. We showed that certain readings of a sensor group are formed for a certain emotional state of a person. We also found that the groups of triggered sensors, their composition, their number, and their location are related to the states of a particular person, which led to the need to build personalized digital pose models for each person. The intellectual component of our hardware–software complex is based on the concept of co-evolutionary hybrid intelligence. The system can be used during medical diagnostic procedures and rehabilitation processes, as well as in controlling people whose professional activity is connected with increased psycho-emotional load and can cause cognitive disorders, fatigue, and professional burnout and can lead to the development of diseases. [ABSTRACT FROM AUTHOR]

As one of the promising human—machine interfaces, wearable sensors play an important role in modern society, which advances the development of wearable fields, especially in the promising applications of electronic skin (e-skin), robotics, prosthetics, and healthcare. In the last decades, wearable sensors tend to be capable of attractive capabilities such as miniaturization, multifunction, and smart integration, and wearable properties such as lightweight, flexibility, stretchability, and conformability for wider applications. In this work, we developed a stretchable multifunctional sensor based on porous silver nanowire/silicone rubber conductive film (P-AgNW/SR). Its unique structural configuration, i.e., an assembly of the P-AgNW/SR with good conductivity, stability, and resistance response, and the insulated silicone rubber layer, provided the feasibility for realizing multiple sensing capabilities. Specifically, porous microstructures of the P-AgNW/SR made the device to be used for pressure sensing, exhibiting outstanding dynamic and static resistive responsive behaviors and having a maximum sensitivity of 9.062 %·N−1 in a continuous compressive force range of ∼ 16 N. With the merit of the good piezoresistive property of AgNW/SR networks embedded into the surface of micropores of the P-AgNW/SR, the device was verified to be a temperature sensor for detecting temperature changes in the human body and environment. The temperature sensor had good sensitivity of 0.844 %·°C−1, high linearity of 0.999 in the range of 25–125 °C, and remarkable dynamic stability. Besides, the developed sensor was demonstrated to be a single electrode-triboelectric sensor for active sensing, owing to the unique assembly of the conductive P-AgNW/SR electrode and the silicone rubber friction layer. Based on the coupling effect of the triboelectrification and electrostatic induction, the generated electrical signals could be used to sense the human motions, according to the quantitative correlation between the human motions and the features in amplitude and waveform of the output signals. Thus, the developed stretchable sensor successfully achieved the integration of two types of passive sensing capabilities, i.e., pressure and temperature sensing, and one type of active sensing capability, i.e., triboelectric sensing, demonstrating the feasibility of monitoring multiple variables of the human body and environment. [ABSTRACT FROM AUTHOR]

The integrated perception capable of detecting and monitoring varieties of activities is one of the ultimate purposes of wearable electronics and intelligent robots. Limited by the space occupation, it lacks practical feasibility to stack multiple types of single sensors on each other. Herein, a high-sensitivity dual-function capacitive sensor with proximity sensing and pressure sensing is proposed. The fringing electric field can be confined in the proximity-sensitive area by fibrous loop-patterned electrode, leading to more stolen charges when object approaching and thus a high proximity sensitivity. The high-permittivity doped structured dielectric layer reduces the compressive stiffness and enhances the rate of compression-caused increase in the equivalent relative permittivity of the dielectric layer, resulting in a larger increase in capacitance and thus a high pressure sensitivity. The electrodes and dielectric layer together compose the capacitor and act as the sensor without taking up additional space. The decoupling of proximity-sensing and pressure-sensing modes can be achieved by decrease or increase in capacitance. Combined with array distribution and sequential scanning, the sensors can be used for detection of motion trajectory, contour recognition, and pressure distribution. [ABSTRACT FROM AUTHOR]

Portable, wearable electronic devices have spurred the rapid development of flexible and stretchable energy harvesting/storage devices with high energy density, superior mechanical stability, and long cycle life. Micro-supercapacitor (MSC) has attracted wide interest due to their advantages of high power density, rapid charge and discharge, and long cycle life. Fabrication of flexible supercapacitors based on laser induced graphene (LIG) has shown strong advantages and potential for flexible sensor power supply. The purpose of this paper is to propose and develop a laser induced flexible micro-supercapacitor (FMSC) for pressure sensors. FMSC is manufactured from a planar forked finger electrode made of graphene induced by CO2 laser radiation commercial Polyimide (PI) film and PVA polymer gel electrolyte. The FMSCs prepared by this method exhibit good electrochemical properties and excellent mechanical properties. The microscopic morphology of LIG was investigated using SEM, and the optimal laser-induced power was determined to be 12.5%. In this paper, a novel fork-finger electrode pattern was applied to improve the performance of FMSCs by optimizing the structure of planar interdigital electrodes, and the FMSCs prepared at 12.5% power showed excellent supercapacitance performance at a voltage window of 0.8 V with a specific capacitance of 2.21 mF/cm2. The FMSCs were made by assembling commercial PI films, PVA, and H3PO4 simple materials, which makes it possible to prepare FMSCs at low cost and high efficiency based on laser direct writing technology. FMSCs provide energy to the flexible sensors and continuously collect energy to charge FMSCs through an integrated flexible energy harvester, which makes FMSCs promising for flexible self-powered wireless sensing platforms.

The proposed work focusses on the 2D design and modelling of integrated microcantilever in microchannel for the analysis of fluid pressure. In order to compute the microfluidic pressure in microchannel at various angles, fluid structure interaction is analyzed using the finite element method. With a fluid flow rate of 4.33 cm/s, a 2D integrated microcantilever can optimize both fluid pressure and microcantilever deflection. The novelty of the microfluidic pressure sensing mechanism allows pressure of fluid to be sensed in a microchannel without connecting any electrical method such as piezoresistor or piezoelectric approach. The objective of the research is to integrate a microcantilever into a microchannel to reduce setup complexity and procedure cost. Maximum deflection of the 2D T-microcantilever achieved 10.30µm at, pressure at the tip of T-microcantilever 10.89 Pa, fluid velocity 0.00309 m/sec, and Reynolds number is 1.22 [ABSTRACT FROM AUTHOR]

This paper discusses the fabrication and characterization of cyclic olefin copolymer (COC)-based pseudo-piezoelectric materials (piezoelectrets) with exceptionally high piezoelectric activity, and their potential use in sensing applications. Piezoelectrets that utilize a novel microhoneycomb structure to achieve high piezoelectric sensitivity are carefully engineered and fabricated at a low temperature using a supercritical CO2-assisted assembly. The quasistatic piezoelectric coefficient d33 of the material can reach up to 12,900 pCN−1 when charged at 8000 V. The materials also exhibit excellent thermal stability. The charge build-up in the materials and the actuation behavior of the materials are also investigated. Finally, applications of these materials in pressure sensing and mapping and in wearable sensing are demonstrated. [ABSTRACT FROM AUTHOR]