Sensitive Pressure Sensor Research Articles

Highly Sensitive and Breathability Flexible Piezoresistive Pressure Sensor Based on Xylon

AbstractIn recent years, the prevalence of cervical spondylosis has been increasing, which is associated with unhealthy posture in daily life, flexible pressure sensors are beneficial in preventing cervical spine disorders. This work is dedicated to developing a flexible, high‐performance, and breathable device to monitor the health of the neck. Here, a flexible pressure sensor with a “sandwich” structure is presented, which incorporates patterned xylon fabric as the substrate and MXene as the sensitive layer. Furthermore, the application of silver nanowires (AgNWs) as the electrode material improves the piezoresistive performance. Combined with an internal elastic encapsulation method (IEEM), the sensor exhibits high sensitivity (1417.9 kPa−1 under pressure below 100 kPa) and a fast response time (30.77 ms). Compared with traditional flexible pressure sensors, the breathability of devices with an all‐fiber structure is nearly seven times higher, which better satisfies the monitoring requirements of long‐term wear. Finally, a wireless system is established by integrating a Bluetooth module and a terminal app. It enables monitoring and sensing of various physiological signals of the neck, as well as identification and alerting of long‐term poor posture such as prolonged neck flexion, showing a potential candidate for the applications of the next‐generation wearable device.

Highly sensitive flexible pressure sensor based on a 1D/2D hybrid aerogel

Wearable pressure sensors with highly sensitive and wide detection ranges are essential for human motion monitoring. In this work, a self-assembled hybrid aerogel was obtained by polyacrylonitrile nanofibers, polyaniline, and reduced graphene oxide. Based on the complementation of 1D and 2D nanomaterials, the aerogel acted like a spring under lower pressure and a membrane under higher pressure, showing great potential in human motion monitoring. According to the wide detection range of the aerogel, an artificial hand was designed to recognize different spatial pressures such as grasping a pen, holding a bottle, and shaking hands. These signal outputs could be precisely reflected by voltage change and further converted to RGB values. Meanwhile, a shoe pad was prepared to monitor foot pressure and the resistance change could be converted to color scale signals. This work provides a new strategy for 1D/2D hybrid nanomaterials-based aerogel with wide pressure ranges in flexible electronics.

A Highly Sensitive Deep-Sea Hydrodynamic Pressure Sensor Inspired by Fish Lateral Line.

Hydrodynamic pressure sensors offer an auxiliary approach for ocean exploration by unmanned underwater vehicles (UUVs). However, existing hydrodynamic pressure sensors often lack the ability to monitor subtle hydrodynamic stimuli in deep-sea environments. In this study, we present the development of a deep-sea hydrodynamic pressure sensor (DSHPS) capable of operating over a wide range of water depths while maintaining exceptional hydrodynamic sensing performance. The DSHPS device was systematically optimized by considering factors such as piezoelectric polyvinylidene fluoride-trifluoroethylene/barium titanate [P(VDF-TrFE)/BTO] nanofibers, electrode configurations, sensing element dimensions, integrated circuits, and packaging strategies. The optimized DSHPS exhibited a remarkable pressure gradient response, achieving a minimum pressure difference detection capability of approximately 0.11 Pa. Additionally, the DSHPS demonstrated outstanding performance in the spatial positioning of dipole sources, which was elucidated through theoretical charge modeling and fluid-structure interaction (FSI) simulations. Furthermore, the integration of a high Young's modulus packaging strategy inspired by fish skull morphology ensured reliable sensing capabilities of the DSHPS even at depths of 1000 m in the deep sea. The DSHPS also exhibited consistent and reproducible positioning performance for subtle hydrodynamic stimulus sources across this wide range of water depths. We envision that the development of the DSHPS not only enhances our understanding of the evolutionary aspects of deep-sea canal lateral lines but also paves the way for the advancement of artificial hydrodynamic pressure sensors.

Ultrahigh sensitive and rapid-response self-powered flexible pressure sensor based on sandwiched piezoelectric composites

Flexible sensors and actuators are the basis for realizing the Internet of Everything. This study identifies specific interfacial polarization and filler dispersion challenges in flexible sensors. A novel sandwich-structured flexible sensor with polydimethylsiloxane (PDMS)-filled Nb2CTx as the interlayer and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]-filled barium titanate (BTO) as the upper and lower layers was designed and fabricated. The thickness of the interlayer was optimized to be 6.2 μm, resulting in an ultrahigh sensitivity of 16.05 V/N and ultrashort response time of 626 μs. The interlayer achieved an oriented arrangement of the dipoles in the upper and lower piezoelectric films through interfacial polarization, enhancing the piezoelectric output and sensitivity. The proposed mechanism was confirmed by the dielectric properties, local piezoelectric response, cross-sectional potential simulation, and interfacial electrical calculations. Additionally, the sensor effectively distinguishes various body movements, facial micro-expressions, and throat vibrations during vocalization, and can be applied to ultrahigh-sensitive self-powered flexible piezoelectric pressure sensors.

3D Printing of Anisotropic Piezoresistive Pressure Sensors for Directional Force Perception.

Anisotropic pressure sensors are gaining increasing attention for next-generation wearable electronics and intelligent infrastructure owing to their sensitivity in identifying different directional forces. 3D printing technologies have unparalleled advantages in the design of anisotropic pressure sensors with customized 3D structures for realizing tunable anisotropy. 3D printing has demonstrated few successes in utilizing piezoelectric nanocomposites for anisotropic recognition. However, 3D-printed anisotropic piezoresistive pressure sensors (PPSs) remain unexplored despite their convenience in saving the poling process. This study pioneers the development of an aqueous printable ink containing waterborne polyurethane elastomer. An anisotropic PPS featuring tailorable flexibility in macroscopic 3D structures and microscopic pore morphologies is created by adopting direct ink writing 3D printing technology. Consequently, the desired directional force perception is achieved by programming the printing schemes. Notably, the printed PPS demonstrated excellent deformability, with a relative sensitivity of 1.22 (kPa*wt. %)-1 over a substantial pressure range (2.8 to 8.1kPa), approximately fivefold than that of a state-of-the-art carbon-based PPS. This study underscores the versatility of 3D printing in customizing highly sensitive anisotropic pressure sensors for advanced sensing applications that are difficult to achieve using conventional measures.

Mechanical-electrical optimization design for the highly sensitive and stable hybrid MXene electrode-based pseudocapacitive pressure sensor

To achieve optimal performance of the flexible sensors, it is common to rely on a large number of trials rather than establishing models to predict or guide in a positive fashion. And in that sense, one has to spend a significant amount of time exploring process parameters, while the experimental results may contain a certain degree of randomness or unpredictability. Here, a mechanical–electrical optimization model is established to design the hybrid film coating thickness. The film coatings, to be specific, are achieved by crosslinking MXene nanosheets with holey reduced graphene oxide using cysteamine. And the coatings can be sprayed on the nickel foam as electrodes and be assembled to a pseudocapacitive pressure device. Through the combined analysis of the mechanical strength, adhesion force, and specific capacitance of the film, the model enables us to objectively evaluate and balance the working range and sensitivity of the device. Consequently, under the guidance of the designed model, the fabricated device with 500 nm thick electrodes exhibits a wide stable working range of 0–865 kPa that coincides with the theoretical prediction, in which the maximum sensitivity achieves to 156359 kPa−1. Ultimately, the sensitive device is used to collect boxing punches to demonstrate its ability to maintain stability during high-pressure repetitive testing, laying the foundation for analyzing and optimizing the striking techniques of athletes.

Ultrafast, self-powered monolithic pressure sensing technology induced by piezo-pyrophototronics

Pressure sensing is a pivotal aspect of modern technology that has been extensively explored, but still presents significant challenges. This work introduces an innovative ultrafast self-powered pressure sensing technology by harnessing the lateral photovoltaic effect (LPE) in a CIGS heterojunction via piezo-pyrophototronics. By utilizing non-uniform irradiation, a surface gradient of charge carriers is induced, resulting in the generation of a lateral photovoltage (LPV) that contributes to the excellent self-powered characteristic of the sensor. This gradient is then coupled with external pressure through the piezo-phototronic effect, enabling the sensing capability of the device. The enhancement of LPV, which is dependent on the irradiation position, power and wavelength, exhibits an extremely linear relationship with the applied external pressure ranging from 0 to 2.0 MPa. Besides, the pyroelectric field generated by transient temperature variations introduces an additional modulation to the pressure sensing effect, leading to an impressive pressure sensitivity of 64.25 mV/MPa, and a rapid response speed of 7.8/8.9 μs. This work highlights the benefits of the lateral photovoltaic effect, piezo-phototronic effect, and pyroelectric modulation in developing highly sensitive and ultrafast self-powered pressure sensors.

Highly Sensitive Pressure Sensor Based on Elastic Conductive Microspheres.

Elastic pressure sensors play a crucial role in the digital economy, such as in health care systems and human-machine interfacing. However, the low sensitivity of these sensors restricts their further development and wider application prospects. This issue can be resolved by introducing microstructures in flexible pressure-sensitive materials as a common method to improve their sensitivity. However, complex processes limit such strategies. Herein, a cost-effective and simple process was developed for manufacturing surface microstructures of flexible pressure-sensitive films. The strategy involved the combination of MXene-single-walled carbon nanotubes (SWCNT) with mass-produced Polydimethylsiloxane (PDMS) microspheres to form advanced microstructures. Next, the conductive silica gel films with pitted microstructures were obtained through a 3D-printed mold as flexible electrodes, and assembled into flexible resistive pressure sensors. The sensor exhibited a sensitivity reaching 2.6 kPa-1 with a short response time of 56 ms and a detection limit of 5.1 Pa. The sensor also displayed good cyclic stability and time stability, offering promising features for human health monitoring applications.

Probing atmospheric waves and the middle atmosphere dynamics using infrasound

Infrasound is defined as pressure fluctuations with frequencies between acoustic cut-off (5 min) and human-hearing frequency threshold of sound (16 Hz). Low-frequent infrasonic waves can travel long distances, ranging from hundreds to thousands of kilometres. The middle atmosphere dynamics mainly control the presence of atmospheric waveguides where energy transmission loss is low. These properties are utilized to record atmospheric explosions at highly sensitive pressure sensors (micro-barometers). A global network of 60 infrasound stations was designed as part of the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty. IMS infrasound stations can record small pressure fluctuations of a few millipascals, which can originate from numerous atmospheric infrasound sources, including meteorological phenomena. In this study, the capability of IMS infrasound arrays for capturing a broad spectrum of atmospheric wave phenomena is highlighted; for instance, mountain-associated infrasonic waves show features that seem to be correlated with orographic gravity waves. Moreover, the interaction of ocean waves produces quasi-continuous infrasound, so-called microbaroms. Infrasonic signatures from microbaroms can be used for probing the middle atmosphere dynamics and assessing atmospheric circulation models. For opening the unique global infrasound network of the IMS for meteorological applications, we also present open-access BGR infrasound data products of two decades and highlight selected case studies.

A personalized electronic textile for ultrasensitive pressure sensing enabled by biocompatible MXene/PEDOT:PSS composite

AbstractFlexible, breathable, and highly sensitive pressure sensors have increasingly become a focal point of interest due to their pivotal role in healthcare monitoring, advanced electronic skin applications, and disease diagnosis. However, traditional methods, involving elastomer film‐based substrates or encapsulation techniques, often fall short due to mechanical mismatches, discomfort, lack of breathability, and limitations in sensing abilities. Consequently, there is a pressing need, yet it remains a significant challenge to create pressure sensors that are not only highly breathable, flexible, and comfortable but also sensitive, durable, and biocompatible. Herein, we present a biocompatible and breathable fabric‐based pressure sensor, using nonwoven fabrics as both the sensing electrode (coated with MXene/poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate [PEDOT:PSS]) and the interdigitated electrode (printed with MXene pattern) via a scalable spray‐coating and screen‐coating technique. The resultant device exhibits commendable air permeability, biocompatibility, and pressure sensing performance, including a remarkable sensitivity (754.5 kPa−1), rapid response/recovery time (180/110 ms), and robust cycling stability. Furthermore, the integration of PEDOT:PSS plays a crucial role in protecting the MXene nanosheets from oxidation, significantly enhancing the device's long‐term durability. These outstanding features make this sensor highly suitable for applications in full‐range human activities detection and disease diagnosis. Our study underscores the promising future of flexible pressure sensors in the realm of intelligent wearable electronics, setting a new benchmark for the industry.

PDMS diaphragm based miniature fiber-optic Fabry-Perot dynamic pressure sensor for turbomachinery application.

Small-sized, highly sensitive dynamic pressure sensors are crucial in the field of turbomachinery application. In this paper, a fiber-tip structure dynamic pressure sensor utilizing a small piece of glass tube as the air cavity and PDMS material as the diaphragm was fabricated. It has the advantage of being small in size with the diameter of 125µm while having high sensitivity of 26.26pm/kPa. The fabrication process was described in detail, which is simple and cost-effective. The sensor characteristics were studied theoretically and experimentally. Quasi-square pressure signal of different frequencies generated by the siren disk were measured by the sensor and compared with that obtained from the commercial piezoresistive pressure sensor to verify the accuracy of the proposed sensor. The R2 of the four pairs of pressure waveforms were 0.94, 0.81, 0.93, and 0.96, respectively. Stability testing of the sensor was also performed, showing that the sensor can work reliably under dynamic pressure environment.

Highly Flexible and Sensitive Pressure Sensor: Fabrication of Porous PDMS/Graphene Composite via Laser Thermoforming

AbstractFlexible pressure sensors employing porous polymer materials are renowned for their superior sensing capabilities, attributed to the inherently low stiffness of porous polymers. The practical utilization of such sensors hinges on the development of a straightforward, cost‐effective, and patternable method for preparing porous polymer materials. In this research, a novel laser thermoforming process is introduced to craft a porous Polydimethylsiloxane (PDMS) film, leveraging carbon black (CB) as an endothermic agent and glucose as a porogen. The resulting porous PDMS film serves as the foundation for a remarkably sensitive flexible piezoresistive sensor. Owing to the inherent flexibility endowed by the porous structure, the porous PDMS‐based pressure sensor achieves a remarkable sensitivity of 109.4 kPa−1 within 0–200 Pa, an effective measurement span of 0–100 kPa, rapid response and recovery times of 79 and 55 ms, and impressive stability over 5000 cycles. The sensor's utility extends to applications such as human pulse monitoring, Morse coding, and robot claw sensing, underscoring its promise in the realm of flexible electronics. In summary, the laser thermoforming process realizes the one‐step, economical, and patternable preparation of porous polymer materials, and introduces a novel avenue for the realization of high‐performance flexible sensors based on thermally cured porous polymers.

Highly sensitive flexible capacitive pressure sensor with structured elastomeric dielectric layers

Sensitive yet stable, robust yet flexible and accurate yet energy efficient pressure sensors are required for variety of purposes. While a large variety of designs and dielectric materials have been explored for this purpose, there is still need of a flexible pressure sensor that will allow easy scale up and inexpensive fabrication. To this end, we have presented here the design of a flexible capacitive pressure sensor using copper coated paper as flexible electrodes and soft Ecoflex layers decorated with cylindrical micro-pillars as the dielectric. While microscopic construct of the sensor allows its easy manufacturability, softness of the layer imparts sensitivity to it. In contrast to many conventional sensors, this design yields sensitivity as high as ∼5 kPa−1 at pressure <1 kPa and somewhat smaller sensitivity as pressure exceeds 1 kPa. We have varied systematically pillar diameter, skin thickness of dielectric layer and pitch of the pillar array to optimise the design and demonstrate its easy tunability. We have presented a model based on buckling of the pillars to predict the response of the sensor. We have explored also a specific design that minimises the hysteresis.

Mechanically Robust and Linearly Sensitive Soft Piezoresistive Pressure Sensor for a Wearable Human-Robot Interaction System.

Soft piezoresistive pressure sensors play an underpinning role in enabling a plethora of future Internet of Things (IoT) applications such as human-robot interaction (HRI) technologies, wearable devices, and metaverse ecosystems. Despite significant attempts to enhance the performance of these sensors, existing sensors still fall short of achieving high strain tolerance and linearity simultaneously. Herein, we present a low-cost, facile, and scalable approach to fabricating a highly strain-tolerant and linearly sensitive soft piezoresistive pressure sensor. Our design utilizes thin nanocracked gold films (NC-GFs) deposited on poly(dimethylsiloxane) (PDMS) as electrodes of the sensor. The large mismatch stress between gold (Au) and PDMS induces the formation of secondary wrinkles along the pyramidal-structured electrode under pressure; these wrinkles function as protuberances on the electrode and enable exceptional linear sensitivity of 4.2 kPa-1 over a wide pressure range. Additionally, our pressure sensor can maintain its performance even after severe mechanical deformations, including repeated stretching up to 30% strain, due to the outstanding strain tolerance of NC-GF. Our sensor's impressive sensing performance and mechanical robustness make it suitable for diverse IoT applications, as demonstrated by its use in wearable pulse monitoring devices and human-robot interaction systems.

Pressure sensor based on Hetero-stack L-shape TFET: simulation study

In this paper, the first-time-ever pressure sensor based on Hetero-stack L-shape TFET has been proposed and investigated through the SILVACO ATLAS TCAD tool. Owing to the hetero-stacking of Germanium material and Silicon material, an enhanced Ion and reduced sub-threshold swing is obtained by the proposed device leading to enhanced Pressure sensor sensitivity. The basic working principle of this proposed pressure sensor device is when pressure is applied to the diaphragm, the diaphragm bends which varies the metal-dielectric thickness of the oxide layer which further alters the electrical characteristics of the proposed pressure sensor. The diaphragm bendings considered in the study are 0, 1, 2, and 2.5 nm. The performance of the proposed pressure sensor device is analyzed through different electrical performance characteristics such as energy band diagrams, electric field, potential, Ion, sub-threshold swing, electron band-to-band tunneling rate, and various other analog/RF parameters at different diaphragm bendings. The effects of ITCs at various bendings are also analyzed to provide an in-depth effect of the factors that might affect the performance of the sensor. The proposed sensor design will be proven as a milestone in the array of sensors built for ultra-sensitive pressure sensing applications.

Hydrogels from chrome shavings for a highly sensitive capacitive pressure sensor

A simple strategy to directly convert chrome shaving collagen fibers into hydrogels with stable surface synapses and abundant pore structures.

Laser speckle grayscale lithography: a new tool for fabricating highly sensitive flexible capacitive pressure sensors

Laser speckle grayscale lithography: a new tool for fabricating highly sensitive flexible capacitive pressure sensors

Bioinspired colloidal crystal hydrogel pressure sensors with Janus wettability for uterus cervical canal tension perception.

The pursuit of flexible, sensitive, and cost-effective pressure sensors plays a pivotal role in medical diagnostics, particularly in the domain of cervical health monitoring. However, significant challenges remain in the economical production of flexible piezoresistive materials and the integration of microstructures aimed at enhancing sensor sensitivity. This urge highlights the use of innovative, stable hydrogel films that demonstrate robust adherence to soft biological tissues, thereby enabling prolonged bio-signal monitoring. In this study, we introduce an innovative integration of a flexible pressure electrical signal sensor with structural color hydrogel scaffolds. This integration leverages the tunability of the inverse opal structure to fine-tune the scaffold's adherence to the endocervical wall under varying environmental conditions and to amplify the sensitivity of pressure measurements. Our findings indicate that this novel approach holds promise for substantial enhancements in the manufacturing and functional capabilities of cervical pressure sensors, potentially revolutionizing personalized medical treatments and improving patient monitoring.

Highly sensitive flexible iontronic pressure sensor for marine pressure monitoring

Highly sensitive flexible iontronic pressure sensor for marine pressure monitoring

A highly sensitive and flexible capacitive pressure sensor based on an ionic hydrogel dielectric layer with a lateral-bending microstructure

The lateral-bending microstructure was inspired by the deformation response of grass under pressure, which exhibits localized deformation under slight compressive loads.