Reliable Pressure Sensors Research Articles

Microchannel pressure sensor for continuous and real-time wearable gait monitoring

A highly sensitive and multi-functional pressure sensor capable of continuous pressure readings is greatly needed, particularly for precise gait pattern analysis. Here, we fabricate a sensitive and reliable pressure sensor by employing eutectic gallium indium (EGaIn) liquid metal as the sensing material and EcoFlex 00-30 silicone as the substrate, via a low-cost process. The device architecture features a microchannel, creating two independent sensing devices, and the mechanical properties of the substrate and sensing material contribute to high stretchability and flexibility, resulting in a sensitivity of 66.07 MPa−1 and a low measurement resolution of 0.056 kPa. The sensor detects applied pressure accurately and can distinguish pressure distribution across a wide area. We demonstrate high efficiency for monitoring human walking gait at various speeds when a single sensor is attached to the foot, and can differentiate between walking postures. This device has strong potential for clinical and rehabilitation applications in gait analysis.

In-situ graft fibrous PPy@PEI enables sensitive and all-seasoned crack monitoring for ancient architectures based on flexible pressure sensors

The non-destructive, real-time, and automatic monitoring for the development of cracks in ancient architectures is crucial to the preservation of precious ancient heritages. Here, light-weight crack sensing constructed with ultra-thin and high-performance flexible pressure sensors is proposed to fulfill this demand. The signal drift and poor reversibility commonly observed in widely-reported sensors based on elastomer matrix, which originates from the creep and relaxation behaviors, are addressed using piezoresistive polypyrrole-grafted polyetherimide fibers. The corresponding flexible piezoresistive sensors exhibit great sensitivity (9.45 kPa−1 in 0 ∼ 1 kPa and 3.48 kPa−1 in 3 ∼ 10 kPa), outstanding static stability (5.13 % signal drift after 48 h under 1 kPa), dynamic durability (4.72 % degradation after ∼30,000 cycles) and excellent robustness across an ultra-wide temperature range of −70 ∼ 150 ℃. Based on this highly reliable pressure sensor, the proposed non-destructive crack sensors integrated into an Internet of Things (IoT) platform display outstanding stability during their service in the Forbidden City. By virtue of the low energy consumption, one lithium battery can power the monitoring system for more than one year.

Dual-Stage Surficial Microstructure to Enhance the Sensitivity of MXene Pressure Sensors for Human Physiological Signal Acquisition.

Accompanying the rapid growth of wearable electronics, flexible pressure sensors have received great interest due to their promising application in health monitoring, human-machine interfaces, and intelligent robotics. The high sensitivity over a wide responsive range, integrated with excellent repeatability, is a crucial requirement for the fabrication of reliable pressure sensors for various wearable scenes. In this work, we developed a highly sensitive and long-life flexible pressure sensor by constructing surficial microarrayed architecture polydimethylsiloxane (PDMS) film as a substrate and Ti3C2TX MXene/bacterial cellulose (BC) hybrid as an active sensing layer. The specific surficial morphology of PDMS couples with nanointercalated structure of Ti3C2Tx MXene/BC can effectively improve the sensitivity through controlling the stress distribution and layer spacing under different levels of pressure loading. In addition, abundant spontaneous hydrogen bonds between BC and Ti3C2Tx MXene nanosheets endow the MXene coating with highly adhesive strength on the PDMS surface; hence, the cyclic stability of the pressure sensor is greatly boosted. As a result, the obtained MXene/BC/PDMS (MBP) pressure sensor delivers high sensitivity (528.87 kPa-1), fast response/recovery time (45 ms/29 ms), low detection limit (0.6 Pa), and outstanding repeatability of up to 8000 cycles. Those excellent sensing properties of the MBP sensor allow it to serve as a reliable wearable device to monitor full-range human physiological motions, and it is expected to be applied in next-generation portable electronics, such as E-skins, smart healthcare, and the Internet of Things technology.

Flexible and Transparent Ionic Liquids/Poly(vinylidene fluoride) Composition‐Gradient Piezo‐Active Composites for Highly Sensitive Pressure Sensor

AbstractNowadays, the advent of pressure sensors for intelligence terminal devices and skin‐inspired electronics has trigged rapid development of flexible, sensitive, and transparent sensing materials. Piezo‐active poly(vinylidene fluoride) (PVDF) is emerging as a promising candidate for sensing components due to the flexible and transparent features. However, the inherent weak piezo‐activity and consequently low sensitivity of PVDF remains a challenge for its sensing applications. Herein, ionic liquids ([EMIM]Cl) additive combined with a composition‐gradient multilayered architecture design are employed to hardness the piezo‐response of PVDF. The resultant composites present ultra‐high piezoelectric coefficient d33 of 39 pC N−1, which is 2.78 times that of PVDF. Meanwhile, the transparent ILs dopant enables the composites with superior transparency (87%). With notable advantages of high transparency and piezoelectricity, the ILs/PVDF composites exhibit high sensitivity of 0.0423 V N−1, ultra‐fast recovery time of 0.2 ms and stable operation capability when coupled with metal electrodes, confirming their applicability for reliable pressure sensor.

EVALUATING A RELIABLE MICROCONTROLLER SYSTEM FOR SITTING BALANCE TREATMENT

Rationale: As time spent seated increases, balanced sitting posture is more important now than ever before. Unbalanced sitting posture deteriorates spinal curvature, which can predispose the pathological discs in the back, leading to irreversible damage. An IoT platform was connected to a chair with pressure sensors attached for this microcontroller device that continuously collected the user's sitting data.
 Procedures: An Arduino Yun microcontroller board was used to monitor sitting posture with the balance feedback system (BFS), which consisted of reliable pressure sensor kits and an IoT platform. Four pressure sensors were coordinated to acquire sitting pressure using the software algorithm, and data was sent to the Thingspeak server and plotted in real-time. The testing session was divided into three stages to verify the system's performance: pre-BFS stage, BFS-Treatment stage, and post-BFS stage. Each stage consisted of the volunteer sitting in the chair for an hour daily for five consecutive days. During the pre-BFS stage, the volunteer sat in the chair to measure their natural seated pressure distribution without using the application. During the BFS-Treatment stage, the volunteer sat in the chair using the application to review pressure data. For the post-BFS stage, the volunteer did not have access to the application in hopes that they could apply their learnings from the previous stage to sit with corrected posture.
 Conclusions: The study concluded that the BFS could monitor the user’s sitting posture and help improve posture to maintain a balanced state. This study can contribute to the prevention of various sitting diseases.

Numerical Study of the Thermal Performance of a Mems Pressure Sensor with Self-Calibration Capabilities.

Recent industry trends toward more complex and interconnected systems have increased the demand for more reliable pressure sensors. By integrating a microactuator with a pressure sensor, the sensor can self-calibrate, eliminating the complexities and costs associated with traditional sensor calibration methods to ensure reliability. The present work is focused on furthering understanding and improving the thermal performance of a thermopneumatic actuated self-calibrating pressure sensor. A transient numerical model was developed in ANSYS and was calibrated using experimental testing data. The numerical model provided insights into the sensor’s performance not previously observed in experimental testing. Furthermore, the model was utilized for two design studies. First, it was found that a substrate with low thermal conductivity and high thermal diffusivity is ideal for both the sensor’s efficiency and a faster transient response time. The second design study showed that decreasing the size of the sealed reference cavity lowers power consumption and transient response time. The study also showed that reducing the cavity base dimension has a greater effect on lowering power consumption and response time. Overall, the present work increases understanding of the self-calibrating pressure sensor and provides insight into potential design improvements, moving closer to optimized self-calibrating pressure sensors.

Highly sensitive, reliable and flexible pressure sensor based on piezoelectric PVDF hybrid film using MXene nanosheet reinforcement

The rapid advances in intelligence terminal devices have raised expectations for highly sensitive, reliable and flexible pressure sensor. Herein, we present a highly sensitive flexible pressure sensor based on piezoelectric MXene/poly(vinylidene fluoride) (PVDF) hybrid film. Making use of MXene nanosheet reinforcement, one can efficiently promote the piezoelectric output and consequently sensitivity of PVDF. For instance, upon a small loading of 0.4 wt%, the piezoelectric coefficient d33 of MXene/PVDF hybrid film reaches the peak of 43 pC/N. Meanwhile, the incorporation of MXene nanosheet is advantageous to strengthen the mechanical performance of PVDF. With the excellent piezoelectric response and mechanical property, the MXene/PVDF hybrid film sensor demonstrates to perform superior voltage sensitivity up to 0.0480 V/N, which is double that of PVDF based sensor. Meanwhile, the novel hybrid film sensor also exhibits fast recovery time of 3.1 ms and stable operation capability under cyclic force, confirming their applicability as reliable pressure sensor.

Amorphous Oxide Semiconductor Transistors with Air Dielectrics for Transparent and Wearable Pressure Sensor Arrays

AbstractFlexible, transparent pressure sensors have numerous potential applications in wearable electronics, soft robotics, health monitoring. In particular, highly sensitive and reliable pressure sensors that cover wide ranges of pressures are promising because they can undergo various external stimulations. Here an unconventional approach is presented for fabricating the active‐matrix array of air‐dielectric, amorphous oxide semiconductor transistors for transparent, wearable pressure sensors. In the structure of these pressure‐sensitive field‐effect transistors (FETs), the clean interface between the air and the oxide semiconductor channel enables the FETs to have outstanding mobility and negligible electrical hysteresis with rapid and reliable responses as pressure sensors for an extensive range of pressures from 200 Pa to 5 MPa. Also, low processing temperature and high transparency of oxide semiconductors make it possible to fabricate them on plastics with flexibility and transparency. The fabrication of active‐matrix pressure sensor arrays demonstrated the real‐time monitoring of freely moving, ultralight, liquid droplets on the sensor. In addition, this can be integrated into the fingertips of gloves to monitor the pressure changes that occur during grasping objects. These results illustrate the potential of pressure sensors to provide robust solutions in the next‐generation electronics including remote surgery, health monitoring, and robotics.

Conformable and ionic textiles using sheath-core carbon nanotube microyarns for highly sensitive and reliable pressure sensors

Conformable and reliable ionic textiles on the basis of sheath-core carbon nanotube microyarns are utilized for implementing highly sensitive and reliable piezocapacitive pressure sensors.

Piezoresistance in Si3N4 nanobelts: toward highly sensitive and reliable pressure sensors

We report the piezoresistance behavior of Si3N4 nanobelts, which is expected to open the door for more studies of highly sensitive and reliable pressure sensors.

SOI-based, High Reliable Pressure Sensor with Floating Concept for High Temperature Applications

In this paper we present a high reliable, accurate and safe, solid state pressure sensor for high temperature applications. The sensor is based on an unique fluid-free technology using a piezoresistive SOI-based chip enclosed in a sealed metal housing. The proprietary housing concept allows a complete separation of the SOI-chip from the measured media. A thick steel membrane and an elongated member (push-rod) transfer the outside pressure into a small deflection of a silicon membrane on the SOI-chip. The thin silicon membrane is engraved by DRIE (Deep Reactive Ion Etching). The sensor is capable to measure pressures up to 1000bar at temperature up to 400°C with an accuracy of ±0,50%FSO. A digital correction enables a compensation of Offset and Sensitivity thermal drifts. The sensor can undergo long-term extreme working conditions without losing its performances.

Influence of radiation damage on ruby as a pressure gauge

This study tackles the question if ruby crystals, irradiated with energetic heavy ions, can still be used as reliable pressure sensors. The problem is linked to novel irradiation experiments, exposing pressurized samples to swift heavy-ion beams. In order to test and quantify a possible influence of radiation damage on the laser-induced fluorescence lines of ruby $({\text{Al}}_{2}{\text{O}}_{3}:{\text{Cr}}^{3+})$, small crystals were exposed to different heavy ions (Xe, Au, and U) with kinetic energies of several giga-electron volt at ambient as well as high-pressure conditions. With increasing fluence $(\text{ions}/{\text{cm}}^{2})$, the ${R}_{1}$ and ${R}_{2}$ lines shift both to lower wavelengths which leads to an underestimation of the pressure. An empirical correction term $\ensuremath{\epsilon}$ is proposed to include the irradiation damage effect into the commonly employed ruby calibration scale.