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[Display omitted] • ANFs/rGOFs composite aerogel is prepared via a controlled directional freezing. • The aerogel features with highly aligned 1D pore arrays in its 3D framework. • ANFs and rGOFs in the aerogel are composited by the interfacial hydrogen bonds. • The aerogel shows a high and reliable piezoresistive sensing performance. • The aerogel sensor is operative in a wide temperature range from −196 to 200 ℃. Aerogel-based conductive materials have emerged as a major candidate for piezoresistive pressure sensors due to their excellent mechanical and electrical performance besides light-weighted and low-cost characteristics, showing great potential for applications in electronic skins, biomedicine, robot controlling and intelligent recognition. However, it remains a grand challenge for these piezoresistive sensors to achieve a high sensitivity across a wide working temperature range. Herein, we report a highly flexible and ultra-light composite aerogel consisting of aramid nanofibers (ANFs) and reduced graphene oxide flakes (rGOFs) for application as a high-performance pressure sensing material in a wide temperature range. By controlling the orientations of pores in the composite framework, the aerogel promotes pressure transfer by aligning its conductive channels. As a result, the ANFs/rGOFs aerogel-based piezoresistive sensor exhibits a high sensitivity of up to 7.10 kPa−1, an excellent stability over 12,000 cycles, and an ultra-wide working temperature range from −196 to 200 °C. It is anticipated that the ANFs/rGOFs composite aerogel can be used as reliable sensing materials in extreme environments. [ABSTRACT FROM AUTHOR]

Piezoresistive pressure sensors have broad applications but often face accuracy challenges due to temperature-induced drift. Traditional compensation methods based on discrete data, such as polynomial interpolation, support vector machine (SVM), and artificial neural network (ANN), overlook the thermal hysteresis, resulting in lower accuracy. Considering the sequence-dependent nature of temperature drift, we propose the RF-IWOA-GRU temperature compensation model. Random forest (RF) is used to interpolate missing values in continuous data. A combination of gated recurrent unit (GRU) networks and an improved whale optimization algorithm (IWOA) is employed for temperature compensation. This model leverages the memory capability of GRU and the optimization efficiency of the IWOA to enhance the accuracy and stability of the pressure sensors. To validate the compensation method, experiments were designed under continuous variations in temperature and actual pressure. The experimental results show that the compensation capability of the proposed RF-IWOA-GRU model significantly outperforms that of traditional methods. After compensation, the standard deviation of pressure decreased from 10.18 kPa to 1.14 kPa, and the mean absolute error and root mean squared error were reduced by 75.10% and 76.15%, respectively. [ABSTRACT FROM AUTHOR]

Piezoresistive pressure sensors have broad applications but often face accuracy challenges due to temperature-induced drift. Traditional compensation methods based on discrete data, such as polynomial interpolation, support vector machine (SVM), and artificial neural network (ANN), overlook the thermal hysteresis, resulting in lower accuracy. Considering the sequence-dependent nature of temperature drift, we propose the RF-IWOA-GRU temperature compensation model. Random forest (RF) is used to interpolate missing values in continuous data. A combination of gated recurrent unit (GRU) networks and an improved whale optimization algorithm (IWOA) is employed for temperature compensation. This model leverages the memory capability of GRU and the optimization efficiency of the IWOA to enhance the accuracy and stability of the pressure sensors. To validate the compensation method, experiments were designed under continuous variations in temperature and actual pressure. The experimental results show that the compensation capability of the proposed RF-IWOA-GRU model significantly outperforms that of traditional methods. After compensation, the standard deviation of pressure decreased from 10.18 kPa to 1.14 kPa, and the mean absolute error and root mean squared error were reduced by 75.10% and 76.15%, respectively.

The increasing interest in karate has also attracted the attention of researchers, especially in combining the equipment used by practitioners with technology to prevent injuries, improve technical skills and provide appropriate scoring. Contrary to the sport of taekwondo, the development of a smart body protector in the sport of karate is still a niche field to be researched. This study focused on developing piezoresistive, textile-based pressure sensors using piezoresistive film, conductive fabric as well as different bonding materials and methods. Primarily, small-scale sensors were produced using ultrasonic welding, hot press welding and oven curing. These were characterized using a universal testing machine and specific conditioning and data-acquisition hardware combined with custom processing software. Large-scale sensors were then manufactured to be placed inside the karate body protector and characterized using cyclic testing. The conditioning circuit allows flexible gain adjustment, and it was possible to obtain a stable signal with an output of up to 0.03 V/N, an adequate signal for the tested force range. The transfer function shows some drift over the cycles, in addition to the expected hysteresis and slight nonlinearity, which can be compensated for. Finally, the configuration with the best results was tested in real practice tests; during these tests the body protector was placed on a dummy as well as on a person. The results showed that the piezoresistive textile-based pressure sensor produced is able to detect and quantify the impact of even light punches, providing an unobtrusive means for performance monitoring and score calculation for competitive practice of this sport. [ABSTRACT FROM AUTHOR]

• A novel starfish-inspired ultrasensitive piezoresistive pressure sensor capable of detecting an extensive range of pressures is proposed. • The sensor's design incorporates high and low spine structures inspired by the surface of a starfish, efficiently preventing rapid saturation of detection range and expanding the response range. • The interaction between the PVA fibers and the PEDOT: PSS/TPU fibers alters the deformation behavior of the sensitive layer fibers, further enhancing the performance of the sensor. • The fabricated sensor demonstrates exceptional sensitivity (302.9 kPa−1), an extensive detection range of 0–426.7 kPa, and remarkable endurance of over 7,000 cycles at 110 kPa. Flexible pressure sensors have attracted significant attention due to their wide range of applications in various fields (e.g., robotis, healthcare, and human–machine interfaces). However, achieving both high sensitivity and a wide detection range remains a challenge. Here, we propose a novel starfish-inspired ultrasensitive piezoresistive pressure sensor capable of detecting an extensive range of pressures. The sensor's design incorporates high and low spine structures inspired by the surface of a starfish, efficiently preventing rapid saturation of detection range and expanding the response range. Unlike single-material nanofiber structures, the ultrathin and ultrasensitive layer, fabricated using PEDOT: PSS/TPU nanofibers, possesses a large surface area ratio and numerous contact points. This allows for a quick increase in conductive channels when pressure is applied. The intertwining of PEDOT: PSS fibers with TPU fibers enhances both the mechanical strength of the fiber membrane and the initial resistance of the sensor, thereby increasing its sensitivity. Additionally, PVA fibers are fabricated over the interdigital electrode to serve as insulation layer for controlling resistance change between the sensitive layer and the electrode. Importantly, the interaction between the PVA fibers and the PEDOT: PSS/TPU fibers alters the deformation behavior of the sensitive layer fibers, further enhancing the performance of the sensor. The fabricated sensor demonstrates exceptional sensitivity (302.9 kPa−1), an extensive detection range of 0–426.7 kPa, and remarkable endurance of over 7,000 cycles at 110 kPa, rendering it a device with great potential for precise pressure sensing applications in health monitoring and intelligent production. [ABSTRACT FROM AUTHOR]

Flexible electronic equipment is an emerging field in recent years, which attaches more attention to be researched and applied in health monitoring and human–machine interface. However, for the existing pressure sensors, even a very slight pressure will greatly reduce their sensitivity, so it is an urgent problem to be solved for achieving high sensitivity and wide application range simultaneously. Hence, a high‐performance piezoresistive pressure sensor based on PAN nanofiber films (PAN NFs) and MXene (Ti3C2Tx) is proposed. The realization of high sensitivity and wide sensing range is based on the microstructure of accordion‐like MXene and the macrostructure of fluffy porous blowing spinning PAN nanofibers, which exhibits a high sensitivity of 81.89 kPa−1 over a wide sensing range of 0.83–38.13 kPa and the dynamic responses to external pressures can reach 98.73 kPa. The pressure sensors based on skin surface‐like 3D patterned interwoven structure are used for health monitoring and tiny pressure detecting. Moreover, the application in human–machine interface is demonstrated. Additionally, to meet the requirement of long‐term wearing, the structure of the sensor is optimized and endowed with excellent breathability and conformal properties, which promotes the further development of flexible electronic equipment. [ABSTRACT FROM AUTHOR]

The development of tunable UV‐curable polymeric composites for functional applications, taking into consideration environmental issues and additive manufacturing technologies, is a research topic with relevant challenges yet to be solved. Herein, acrylic composites filled with 0–3 wt.%. polyaniline/ multiwalled carbon nanotubes (PANI/MWCNT) are prepared by Digital Light Processing (DLP) in order to tailor morphology, thermal, mechanical, and electromechanical properties. Viscosity, real‐time infrared spectroscopy, and cure depth tests allow optimizing resin composition for suitable DLP printing. 2 wt.% is the maximum filler content reproducibly embedded in the polymer matrix. The advantages of PANI/MWCNT (50/50 wt.%) compared with single‐component composites include safety issues, enhanced printability, increased electrical conductivity and thermal stability, and lower electrical percolation threshold (0.83 wt.%). Above this threshold the composites display excellent piezoresistive response, no hysteresis, and stability for over 400 compression cycles. The pressure sensibility (PS) of 2 wt.% composites decreases with applied pressure from PS ≈ 15 to 0.8 Mpa−1 for maximum pressures of 0.02 and 0.57 MPa, respectively. A proof‐of‐concept of the functionality of the novel materials is developed in the form of a tactile sensor, demonstrating their potential for pressure sensing applications as cost‐effective, sustainable, and flexible materials for printed electronics. [ABSTRACT FROM AUTHOR]

The increasing interest in karate has also attracted the attention of researchers, especially in combining the equipment used by practitioners with technology to prevent injuries, improve technical skills and provide appropriate scoring. Contrary to the sport of taekwondo, the development of a smart body protector in the sport of karate is still a niche field to be researched. This study focused on developing piezoresistive, textile-based pressure sensors using piezoresistive film, conductive fabric as well as different bonding materials and methods. Primarily, small-scale sensors were produced using ultrasonic welding, hot press welding and oven curing. These were characterized using a universal testing machine and specific conditioning and data-acquisition hardware combined with custom processing software. Large-scale sensors were then manufactured to be placed inside the karate body protector and characterized using cyclic testing. The conditioning circuit allows flexible gain adjustment, and it was possible to obtain a stable signal with an output of up to 0.03 V/N, an adequate signal for the tested force range. The transfer function shows some drift over the cycles, in addition to the expected hysteresis and slight nonlinearity, which can be compensated for. Finally, the configuration with the best results was tested in real practice tests; during these tests the body protector was placed on a dummy as well as on a person. The results showed that the piezoresistive textile-based pressure sensor produced is able to detect and quantify the impact of even light punches, providing an unobtrusive means for performance monitoring and score calculation for competitive practice of this sport.

Micro electromechanical systems (MEMS) micro-pressure sensors have wide applications in consumer electronics, industrial monitoring, and biomedicine. However, as the next-generation portable and wearable devices bloom in recent years, existing design of pressure sensors faces great challenges to break the trade-off between the sensitivity and nonlinearity in the miniaturization process. Here, we report a sandwich-like Graphene/h-BN/Graphene-resistor heterostructure sensing element for micro-pressure detection. This novel design decouples pressure-to-strain translation process and strain-to-electrical signal sensing process by the insulation of bottom graphene structure layer and top graphene piezoresistive layer. We reveal the effects of the heterostructure dimensions, layer number and pretension on the mechanical performance utilizing finite element method (FEM) simulation, and propose the design principle of the piezoresistors and patterning strategy of the heterostructure. Remarkably, the heterostructure exhibits ultra-high sensitivity per unit area, outperforming state-of-art graphene and silicon-based sensors by up to five orders of magnitude, as well as a significant reduction of the nonlinearity. Our work shows tremendous potential of 2D material heterostructure as a promising platform to break the miniaturization limitation of ultrasensitive pressure sensors. [Display omitted] • Graphene/h-BN/Graphene van der Waals heterostructure was proposed for pressure sensing with footprint reduced to 6×6 μm2. • Sensitivity and linearity were improved compared to suspending graphene-based sensor by a factor of 28 and 16, respectively. • Area-normalized sensitivity of heterostructure was 2 to 5 orders of magnitude superior to silicon and graphene-based sensors. [ABSTRACT FROM AUTHOR]

Motivated by the inevitable trend of the Internet of Everything, human-machine interaction technology has gradually been permeated into people's daily life. Receptive devices that capture human behaviors and responsive devices that provide machine feedback are key components of human-machine interface. While it is a great challenge to integrate receptive and responsive devices in a well-organized way due to the limitations of material properties and device structures. In this work, we investigate the formation of laser-induced graphene on Nomex paper and propose an efficient interactive strategy based on its piezoresistive and thermoacoustic effects. Functional integration of receiving instructions (pressure-sensing capability) and providing feedback (sound-emitting capability) can be achieved by simply assembling three layers of Nomex paper that have been laser-customized on both sides. The integrated device not only has a sensitive response (∼12 relative current change and ∼50 ms response time) to the pressure similar to a gentle finger press (∼10 kPa), but also can emit a high-quality sound signal with larger sound pressure levels (∼70 dB at 1 W/cm2 power density). Furthermore, two proof-of-concept demonstrations, a press-to-audio pad and a command-responding thermo-earphone, are presented to substantiate the feasibility in information exchange activities. [Display omitted] • Laser-induced graphene layers with favorable electrical conductivity are formed on Nomex paper. • Different conductive properties between double-sided laser-induced graphene across Nomex substrate are obtained by regulating laser power. • Pressure-sensing and sound-emitting capabilities are realized taking advantage of piezoresistive and thermoacoustic effects of laser-induced graphene. • Multifunctional integration is implemented by assembling three-layer Nomex paper that feature double-sided laser-induced graphene. [ABSTRACT FROM AUTHOR]

Three types of piezoresistive pressure sensors were designed and fabricated using different process technologies incorporating standard diffused piezoresistors, and oxide isolated polysilicon or single crystal silicon piezoresistors. The performance of these sensors up to an elevated temperature of 200°C and pressure of 140 bar was investigated by measuring the variation of sensitivity, offset voltage and hysteresis. At room temperature, the diffused piezoresistor based pressure sensor demonstrated sensitivity of 0.147 mV/V/bar and it was observed to operate up to the maximum temperature of 100 °C. The oxide isolated single crystal silicon piezoresistor and polysilicon piezoresistor based pressure sensors showed sensitivities of 0.211 mV/V/bar and 0.308 mV/V/bar respectively at room temperatures. These sensors could be operated up to the measured temperature of 200 °C without any failure. All types of sensors showed decreased sensitivities with temperature. With respect to the sensitivity at room temperature, the sensor with diffused piezoresistors exhibited 13% decrease of sensitivity at 100 °C. For oxide isolated single crystal silicon or poly silicon piezoresistors, the decrease in the sensitivity at 200 °C was 19.5% and 9.0% respectively y. At elevated temperatures of 200 °C, the sensors with oxide isolated polysilicon piezoresistors demonstrated the best performance in terms of lowest decrease of sensitivity, and variation of offset voltage and hysteresis. [ABSTRACT FROM AUTHOR]

Fabrics are among the best ideal materials for fabricating low‐cost flexible pressure sensors due to their outstanding air permeability, flexibility, and micro/nanorough structure. However, most of the fabric‐based pressure sensors suffer from poor stability, which severely limits their applications in the real life. In the previous work, the pressure sensor assembled from polyester fabric and polyurethane sponge in an integrated design shows good stability. Herein, a novel type of wearable pressure sensors with high sensitivity and long durability is prepared by the unique combination of a dense integrated material consisting of nylon fabric–latex sponge–nylon fabric (FSF), reduced graphene oxide (rGO), and in‐situ‐formed polypyrrole (PPy). Benefiting from the excellent electrical conductivity, compression performance, and piezoresistive property, the obtained PPy/rGO/FSF pressure sensor exhibits low operating voltage (1.0 V), high sensitivity (0.51 kPa−1), long durability (over 7500 cycles), as well as short response time (243 ms). As a result, the pressure sensor demonstrates high performance in monitoring human activities such as wrist pulses, exhalation/inhalation, head shaking, knee bending, and finger bending, indicating its great potential in human health monitoring and human–computer interaction. [ABSTRACT FROM AUTHOR]

Paper-based flexible pressure sensors have received extensive attention owing to their recoverability and accessibility. This study, proposes a graphical pressure sensor array with a multilayered structure. A simple writing method is adopted to realize the adsorption of sensitive materials on the fiber structure of cellulose paper. Pressure sensors with 1, 3, 5, and 7 stacked layers are fabricated and compared. The results show that the seven-layer sensor achieves a high sensitivity (44 kPa-1) and fast time response (less than 150 ms). The highly sensitive stacked paper-based sensor array realizes the pressure detection in objects and special-shaped surfaces. A pressure sensor based on a commercial corrugated box is also fabricated for comparison. The corrugated carton array is used to switch the reminder devices for convenience and accessibility. Because many scenarios require a safe distance to be maintained, particularly under the influence of COVID-19, the writable paper-based sensor array is used to realize graphical distance perception and provide warnings. [ABSTRACT FROM AUTHOR]

Due to its porous structure and good elasticity, conductive polyurethane (PU) sponge is used as the main substrate of the flexible piezoresistive pressure sensor. The effective combination of conductive PU sponge and electrode material is the foundation for the pressure sensor, but it needs to be bonded by expensive conductive silver paste or copper paste. In addition, the common electrode materials weaken the flexibility of the PU sponge pressure sensors because of their rigidity. Herein, PU sponge and polyester (PET) fabric are first bonded to produce (PET‐PU) composite, which is then impregnated with graphene oxide (GO). The obtained reduced graphene oxide(rGO)@PET fabric and rGO@PU are used as electrode and piezoresistive material, respectively. Then rGO@(PET‐PU) composite is assembled into a pressure sensor only by using wire connections in the rGO@PET fabric. Benefiting from excellent piezoresistive behavior, rGO@(PET‐TPU) pressure sensor displays high sensitivity (0.255 kPa−1 at below 2.6 kPa), wide detection limit (≈0–85.0%), and long durability (over 1800 cycles). Besides, the pressure sensor demonstrates good performance in monitoring human activities, including finger bending, clicking keyboard, breathing, elbow bending, and walking posture, thus providing a promising material for human activity monitoring. [ABSTRACT FROM AUTHOR]

Piezoresistive pressure sensors based on sponge are widely concerned because of their wide strain range, convenient signal acquisition, and good compressibility, yet it is still a challenge to acquire sponge‐based pressure sensors with low cost and excellent sensing performance. Herein, low‐priced FeCl3.6H2O and pyrrole (Py) are dispersed in deionized water to form FeCl3.6H2O/Py solution. Commercial latex sponge is impregnated into this solution to prepare conductive polypyrrole/latex (PPy/latex) sponge through low‐temperature interfacial polymerization. The surface of latex sponge is covered by the micro‐wrinkled PPy, which endows the PPy/latex sponge with a certain electrical conductivity. The specific porous structure and high elasticity of the latex sponge are the basic conditions for PPy/latex sponge excellent piezoresistive behaviors. PPy/latex sponge based piezoresistive pressure sensor shows high sensitivity (0.084 kPa−1 at below 3.12 kPa), wider sensing range (0–85.0%) and long durability over 3800 s (1800 cycles). At the same time, the ability of the PPy/latex sponge based piezoresistive pressure sensor to monitor human movement has been successfully evaluated in some application scenarios, such as bending fingers, grabbing objects, tiptoe rising, and crouching. [ABSTRACT FROM AUTHOR]

Abstract Fabricating flexible pressure sensors with high sensitivity in a broad pressure range is still a challenge. Herein, a flexible pressure sensor with engineered microstructures on polydimethylsiloxane (PDMS) film is designed. The high performance of the sensor derives from its unique pyramid‐wall‐grid microstructure (PWGM). A square array of dome‐topped pyramids and crossed strengthening walls on the film forms a multiheight hierarchical microstructure. Two pieces of PWGM flexible PDMS film, stacked face‐to‐face, form a piezoresistive sensor endowed with ultrahigh sensitivity across a very broad pressure range. The sensitivity of the device is as high as 383 665.9 and 269 662.9 kPa−1 in the pressure ranges 0–1.6 and 1.6–6 kPa, respectively. In the higher pressure range of 6.1–11 kPa, the sensitivity is 48 689.1 kPa−1, and even in the very high pressure range of 11–56 kPa, it stays at 1266.8 kPa−1. The pressure sensor possesses excellent bending and torsional strain detection properties, is mechanically durable, and has potential applications in wearable biosensing for healthcare. In addition, 2 × 2 and 4 × 4 sensor arrays are prepared and characterized, suggesting the possibility of manufacturing a flexible tactile sensor.

Fabricating flexible pressure sensors with high sensitivity in a broad pressure range is still a challenge. Herein, a flexible pressure sensor with engineered microstructures on polydimethylsiloxane (PDMS) film is designed. The high performance of the sensor derives from its unique pyramid‐wall‐grid microstructure (PWGM). A square array of dome‐topped pyramids and crossed strengthening walls on the film forms a multiheight hierarchical microstructure. Two pieces of PWGM flexible PDMS film, stacked face‐to‐face, form a piezoresistive sensor endowed with ultrahigh sensitivity across a very broad pressure range. The sensitivity of the device is as high as 383 665.9 and 269 662.9 kPa−1 in the pressure ranges 0–1.6 and 1.6–6 kPa, respectively. In the higher pressure range of 6.1–11 kPa, the sensitivity is 48 689.1 kPa−1, and even in the very high pressure range of 11–56 kPa, it stays at 1266.8 kPa−1. The pressure sensor possesses excellent bending and torsional strain detection properties, is mechanically durable, and has potential applications in wearable biosensing for healthcare. In addition, 2 × 2 and 4 × 4 sensor arrays are prepared and characterized, suggesting the possibility of manufacturing a flexible tactile sensor. [ABSTRACT FROM AUTHOR]

Pressure sensors have attracted tremendous attention because of their potential applications in the fields of health monitoring, human–machine interfaces, artificial intelligence, and so on. Improving pressure‐sensing performances, especially the sensitivity and the detection limit, is of great importance to expand the related applications, however it is still an enormous challenge so far. Herein, highly sensitive piezoresistive pressure sensors are reported with novel light‐boosting sensing performances. Rose petal–templated positive multiscale millimeter/micro/nanostructures combined with surface wrinkling nanopatterns endow the assembled pressure sensors with outstanding pressure sensing performance, e.g. an ultrahigh sensitivity (70 KPa−1, <0.5 KPa), an ultralow detection limit (0.88 Pa), a wide pressure detect ion range (from 0.88 Pa to 32 KPa), and a fast response time (30 ms). Remarkably, simple light illumination further enhances the sensitivity to 120 KPa−1 (<0.5 KPa) and lowers the detection limit to 0.41 Pa. Furthermore, the flexible light illumination offers unprecedented capabilities to spatiotemporally control any target in multiplexed pressure sensors for optically enhanced/tailorable sensing performances. This light‐control strategy coupled with the introduction of bioinspired multiscale structures is expected to help design next generation advanced wearable electronic devices for unprecedented smart applications. [ABSTRACT FROM AUTHOR]

Improvement of sensitivity of electrical piezoresistive sensors is critical for high‐precision and ultrasensitive detection, which mainly depends on the modulation ability of total resistance of sensor under applied pressure. However, in most of the reported sensor devices, the contact resistance and body resistance (the key parts of total resistance of sensor) generally cannot be modulated simultaneously, which results in the limited sensitivity. In this work, an ultrahighly sensitive piezoresistive pressure sensor with an exquisitely designed structure is demonstrated, providing an uncomparable advantage of synergistic modulation of contact resistance and body resistance under applied pressure. As a result, the sensor shows excellent sensing performance, with the highest sensitivity up to 11 668.6 kPa−1, the detection limit as low as 0.425 Pa, and the great stability over 20 000 cycle measurements. In respect of practical application, the high sensitivity endows the sensor with high‐precision recognition ability for detecting the weak pressure signals such as sound wave of ringtone and fluctuation of breath or pulse. These results suggest the synergistic resistance modulation to be an effective method toward piezoresistive pressure sensors with ultrahigh sensitivity and offer a new strategy for the achievement of high‐performance pressure sensors. [ABSTRACT FROM AUTHOR]

In this work, piezoresistive properties of graphene-multiwalled carbon nanotubes (MWCNTs) composites are investigated, characterized, and compared. Sandwich-type composite piezoresistive pressure-sensitive sensors (Ag/Graphene-MWCNT/Ag) with the same diameters, but different fabrication pressures and thicknesses were fabricated using the mortar and pestle/hydraulic press technique. To produce low-electrical-resistance contacts, both sides of the composite sensors were painted with silver (Ag) paste. All the sensors showed reductions in the direct current (DC) resistance ‘R’ with an increment in external uniaxial applied pressure. However, it was observed that higher fabrication pressure led to a lower resistance value of the composite, while the thicker samples give lower electrical conductivity and higher resistance than the thinner samples. The experimental data for all composite pressure sensors were in excellent agreement with the simulated results.

Piezoresistive pressure sensors have attracted much attention for their potential applications in health monitoring, wearable devices, electronic skin and smart robots. Herein, we report an innovative strategy to fabricate multilayer piezoresistive pressure sensors with polydimethylsiloxane anchored carbonized cotton fabric (PACCF). Due to the good conductivity of carbonized cotton fabric and the multilayer structure to construct three-dimensional conductive network, the sensor possessed not only a wide pressure detection range, but also an ultrahigh sensitivity of 13.89 kPa−1 (0–6 kPa). Moreover, the sensor also exhibited fast response and excellent repeatability even after 500 loading–unloading cycles. Importantly, the sensor was successfully applied for detecting pulses, airflow, weak vibration and various body motions. Additionally, the sensors integrated sensing matrix also realized mapping and identifying spatial pressure distribution. Our method to fabricate PACCF-based multilayer piezoresistive pressure sensor is simple, efficient and low-cost; no special equipment or chemicals is required, and cotton as main raw material is natural and renewable, which is very beneficial for large-scale production. Our findings conceivably stand out as a new tool to fabricate high-performance pressure sensors in the fields of healthcare and emerging intelligent electronics. [ABSTRACT FROM AUTHOR]

Recently, significant activities have been focused on the research of human identification and tracking systems in different environments. In this context, this paper describes a novel design and construction methodology for a low-cost intelligent carpet system for footstep detection. The carpet consists of activated carbon nonwoven material sandwiched between a pair of cross-aligned conductive wires to form in situ piezoresistive sensors. The assembly is externally covered with textiles to form a regular carpet. An electronic interface device and data treatment system is developed to monitor human footstep action-based piezoresistive changes observed within the carpet. The system is further practically validated for human footstep detection, localization, and counting. To demonstrate the potential application in human foot-step-based tracking, seven Gait features were extracted from piezoresistance change profile formed by human walking on the carpet and subsequently, a walking signature has been introduced. It is anticipated that such an intelligent carpet that retains its flexibility and textile aesthetics can be a good alternative for the conventional textile carpet with auxiliary functionality and added value. [ABSTRACT FROM PUBLISHER]

Introduction:BioMEMS relates to the implementation of Micro-Electro-Mechanical Systems (MEMS), in the biological and medical sphere. BioMEMS sensors are being utilized for many clinical applications, including a wireless urinary pressure system, right heart pressure sensor, and measurements on shearing force on the vascular system An important application of BioMEMS is on Heart failure (HF), a common disease, with a prevalence of 10% or more in persons 70 years of age or older, associated with high morbidity and mortality. HF affects over 5 million people and contributes to over 200,000 deaths a year in the United States alone. Areas covered:The purpose of this paper is to provide a short overview on the successful implementation of BioMEMS sensors in heart failure and vascular medicine. Expert commentary:BioMEMS devices have overcome current limitations in pharmacotherapies for resistant hypertension by electrical modulation of the baroreceeptors. This represents a step towards the development of biomedical micro-devices for those conditions in which pharmacotherapies result poorly effective or elicit unacceptable toxicity. [ABSTRACT FROM AUTHOR]

Thermal drift caused by Joule heating in piezoresistive pressure sensors affects greatly the results in the shift of the offset voltage of the such sensors. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristic drift. The impact of Joule heating in a pressure sensor has been studied. The study involves the solution of heat transfer equation considering the conduction in Cartesian coordinates for the transient regime using Finite Difference Method. We determine how the temperature affects the sensor during the applying a supply voltage. For this, the temperature rise generated by Joule heating in piezoresistors has been calculated for different geometrical parameters of the sensor as well as for different operating time. It is observed that Joule heating leads to important rise temperature in the piezoresistor and, hence, causes drift in the output voltage variations in a sensor during its operated in a prolonged time. This paper put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. The optimization of geometric parameters of sensor allows us to reducing the internal heating effect. Results showed also that low bias voltage should be applied for reducing Joule heating. [ABSTRACT FROM AUTHOR]