scholarly journals Flexible Wireless Passive LC Pressure Sensor with Design Methodology and Cost-Effective Preparation

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 976
Author(s):  
Zhuqi Sun ◽  
Haoyu Fang ◽  
Baochun Xu ◽  
Lina Yang ◽  
Haoran Niu ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Electronic Device ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Capacitive Pressure Sensor ◽  
Intimate Contact ◽  
Physical Motion ◽  
Readout Device ◽  
Wearable Electronic Device

Continuous monitoring of physical motion, which can be successfully achieved via a wireless flexible wearable electronic device, is essential for people to ensure the appropriate level of exercise. Currently, most of the flexible LC pressure sensors have low sensitivity because of the high Young’s modulus of the dielectric properties (such as PDMS) and the inflexible polymer films (as the substrate of the sensors), which don’t have excellent stretchability to conform to arbitrarily curved and moving surfaces such as joints. In the LC sensing system, the metal rings, as the traditional readout device, are difficult to meet the needs of the portable readout device for the integrated and planar readout antenna. In order to improve the pressure sensitivity of the sensor, the Ecoflex microcolumn used as the dielectric of the capacitive pressure sensor was prepared by using a metal mold copying method. The Ecoflex elastomer substrates enhanced the levels of conformability, which offered improved capabilities to establish intimate contact with the curved and moving surfaces of the skin. The pressure was applied to the sensor by weights, and the resonance frequency curves of the sensor under different pressures were obtained by the readout device connected to the vector network analyzer. The experimental results show that resonant frequency decreases linearly with the increase of applied pressure in a range of 0–23,760 Pa with a high sensitivity of −2.2 MHz/KPa. We designed a coplanar waveguide-fed monopole antenna used to read the information of the LC sensor, which has the potential to be integrated with RF signal processing circuits as a portable readout device and a higher vertical readout distance (up to 4 cm) than the copper ring. The flexible LC pressure sensor can be attached to the skin conformally and is sensitive to limb bending and facial muscle movements. Therefore, it has the potential to be integrated as a body sensor network that can be used to monitor physical motion.

Development of circuit solution and design of capacitive pressure sensor array for applied robotics

2020 ◽  
Vol 8 (4) ◽  
pp. 296-307
Author(s):  
Konstantin Krestovnikov ◽  
Aleksei Erashov ◽  
Аleksandr Bykov
Keyword(s):  
Pressure Sensor ◽  
Output Signal ◽  
Sensor Array ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Fine Tuning ◽  
Capacitive Pressure Sensor ◽  
Cell Parameters ◽  
Linear Pattern ◽  
Sensor Structure

This paper presents development of pressure sensor array with capacitance-type unit sensors, with scalable number of cells. Different assemblies of unit pressure sensors and their arrays were considered, their characteristics and fabrication methods were investigated. The structure of primary pressure transducer (PPT) array was presented; its operating principle of array was illustrated, calculated reference ratios were derived. The interface circuit, allowing to transform the changes in the primary transducer capacitance into voltage level variations, was proposed. A prototype sensor was implemented; the dependency of output signal power from the applied force was empirically obtained. In the range under 30 N it exhibited a linear pattern. The sensitivity of the array cells to the applied pressure is in the range 134.56..160.35. The measured drift of the output signals from the array cells after 10,000 loading cycles was 1.39%. For developed prototype of the pressure sensor array, based on the experimental data, the average signal-to-noise ratio over the cells was calculated, and equaled 63.47 dB. The proposed prototype was fabricated of easily available materials. It is relatively inexpensive and requires no fine-tuning of each individual cell. Capacitance-type operation type, compared to piezoresistive one, ensures greater stability of the output signal. The scalability and adjustability of cell parameters are achieved with layered sensor structure. The pressure sensor array, presented in this paper, can be utilized in various robotic systems.

scholarly journals Modeling of a square-shape ZnO, ZnS and AlN membrane for mems capacitive pressure-sensor applications

2020 ◽  
Vol 11 ◽  
pp. 14
Author(s):  
Ahmad Dagamseh ◽  
Qais Al-Bataineh ◽  
Zaid Al-Bataineh ◽  
Nermeen S. Daoud ◽  
Ahmad Alsaad ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Pressure Sensor ◽  
Membrane Structure ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Membrane Thickness ◽  
Capacitive Pressure Sensor ◽  
The Finite Element Method ◽  
Sensor Applications ◽  
Opposite Behavior

In this paper, mathematical modeling and simulation of a MEMS-based clamped square-shape membrane for capacitive pressure sensors have been performed. Three types of membrane materials were investigated (i.e. Zinc Oxide (ZnO), Zinc Sulfide (ZnS) and Aluminum Nitride (AlN)). Various performance parameters such as capacitance changes, deflection, nonlinearity, the sensitivity of the membrane structure for different materials and film-thicknesses have been considered using the Finite Element Method (FEM) and analytically determined using the FORTRAN environment. The simulation model outperforms in terms of the effective capacitance value. The results show that the membrane deflection is linearly related to the applied pressure. The ZnS membrane provides a capacitance of 0.023 pico-Farad at 25 kPa with a 42.5% relative capacitance changes to reference capacitance. Additionally, the results show that for ZnO and AlN membranes the deflection with no thermal stress is higher than that with thermal stress. However, an opposite behavior for the ZnS membrane structure has been observed. The mechanical and capacitance sensitivities are affected by the membrane thickness as the capacitance changes are inversely proportional to the membrane thickness. Such results open possibilities to utilize various materials for pressure sensor applications by means of the capacitance-based detection technique.

A capacitive sensor using resin thermoplastic elastomer and carbon fibers for monitoring pressure distribution

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guanzheng Wu ◽  
Siming Li ◽  
Jiayu Hu ◽  
Manchen Dong ◽  
Ke Dong ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fibers ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Thermoplastic Elastomer ◽  
Gauge Factor ◽  
Capacitive Pressure Sensor ◽  
Wearable Electronics ◽  
Content Type

Purpose This paper aims to study the working principle of the capacitive pressure sensor and explore the distribution of pressure acting on the surface of the capacitor. Herein, a kind of high sensitivity capacitive pressure sensor was prepared by overlaying carbon fibers (CFs) on the surfaces of the thermoplastic elastomer (TPE), the TPE with high elasticity is a dielectric elastomer for the sensor and the CFs with excellent electrical conductivity were designed as the conductor. Design/methodology/approach Due to the excellent mechanical properties and electrical conductivity of CFs, it was designed as the conductor layer for the TPE/CFs capacitive pressure sensor via laminating CFs on the surfaces of the columnar TPE. Then, a ‘#' type structure of the capacitive pressure sensor was designed and fabricated. Findings The ‘#' type of capacitive pressure sensor of TPE/CFs composite was obtained in high sensitivity with a gauge factor of 2.77. Furthermore, the change of gauge factor values of the sensor under 10 per cent of applied strains was repeated for 1,000 cycles, indicating its outstanding sensing stability. Moreover, the ‘#' type capacitive pressure sensor of TPE/CFs was consisted of several capacitor arrays via laminating CFs, which could detect the distribution of pressure. Research limitations/implications The TPE/CFs capacitive pressure sensor was easily fabricated with high sensitivity and quick responsiveness, which is desirably applied in wearable electronics, robots, medical devices, etc. Originality/value The outcome of this study will help to fabricate capacitive pressure sensors with high sensitivity and outstanding sensing stability.

scholarly journals Highly Sensitive Textile-Based Capacitive Pressure Sensors Using PVDF-HFP/Ionic Liquid Composite Films

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 442
Author(s):  
Kyobin Keum ◽  
Jae Sang Heo ◽  
Jimi Eom ◽  
Keon Woo Lee ◽  
Sung Kyu Park ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Pressure Sensor ◽  
Sensor Array ◽  
Vinylidene Fluoride ◽  
Composite Films ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Capacitive Pressure Sensor ◽  
Electronic Textiles ◽  
Poly Vinylidene Fluoride

Textile-based pressure sensors have garnered considerable interest in electronic textiles due to their diverse applications, including human–machine interface and healthcare monitoring systems. We studied a textile-based capacitive pressure sensor array using a poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)/ionic liquid (IL) composite film. By constructing a capacitor structure with Ag-plated conductive fiber electrodes that are embedded in fabrics, a capacitive pressure sensor showing high sensitivity, good operation stability, and a wide sensing range could be created. By optimizing the PVDF-HFP:IL ratio (6.5:3.5), the fabricated textile pressure sensors showed sensitivity of 9.51 kPa−1 and 0.69 kPa−1 in the pressure ranges of 0–20 kPa and 20–100 kPa, respectively. The pressure-dependent capacitance variation in our device was explained based on the change in the contact-area formed between the multi-filament fiber electrodes and the PVDF-HFP/IL film. To demonstrate the applicability and scalability of the sensor device, a 3 × 3 pressure sensor array was fabricated. Due to its matrix-type array structure and capacitive sensing mechanism, multi-point detection was possible, and the different positions and the weights of the objects could be identified.

scholarly journals A new strategy for the fabrication of a flexible and highly sensitive capacitive pressure sensor

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ruzhan Qin ◽  
Mingjun Hu ◽  
Xin Li ◽  
Te Liang ◽  
Haoyi Tan ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Capacitive Sensor ◽  
Capacitive Pressure Sensor ◽  
Interdigital Electrode ◽  
Interdigital Electrodes ◽  
Highly Sensitive ◽  
New Strategy ◽  
Application Prospects

AbstractThe development of flexible capacitive pressure sensors has wide application prospects in the fields of electronic skin and intelligent wearable electronic devices, but it is still a great challenge to fabricate capacitive sensors with high sensitivity. Few reports have considered the use of interdigital electrode structures to improve the sensitivity of capacitive pressure sensors. In this work, a new strategy for the fabrication of a high-performance capacitive flexible pressure sensor based on MXene/polyvinylpyrrolidone (PVP) by an interdigital electrode is reported. By increasing the number of interdigital electrodes and selecting the appropriate dielectric layer, the sensitivity of the capacitive sensor can be improved. The capacitive sensor based on MXene/PVP here has a high sensitivity (~1.25 kPa−1), low detection limit (~0.6 Pa), wide sensing range (up to 294 kPa), fast response and recovery times (~30/15 ms) and mechanical stability of 10000 cycles. The presented sensor here can be used for various pressure detection applications, such as finger pressing, wrist pulse measuring, breathing, swallowing and speech recognition. This work provides a new method of using interdigital electrodes to fabricate a highly sensitive capacitive sensor with very promising application prospects in flexible sensors and wearable electronics.

Flexible Capacitive Pressure Sensors with Micro-Patterned Porous Dielectric Layer for Wearable Electronics

2022 ◽  
Author(s):  
Jing Wang ◽  
Longwei Li ◽  
Lanshuang Zhang ◽  
Panpan Zhang ◽  
Xiong Pu
Keyword(s):  
Pressure Sensor ◽  
Flexible Electronics ◽  
Dielectric Layer ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Capacitive Sensor ◽  
Human Motion ◽  
Capacitive Pressure Sensor ◽  
Wearable Electronics ◽  
Emulsified Water

Abstract Highly sensitive soft sensors play key roles in flexible electronics, which therefore have attracted much attention in recent years. Herein, we report a flexible capacitive pressure sensor with high sensitivity by using engineered micro-patterned porous polydimethylsiloxane (PDMS) dielectric layer through an environmental-friendly fabrication procedure. The porous structure is formed by evaporation of emulsified water droplets during PDMS curing process, while the micro-patterned structure is obtained via molding on sandpaper. Impressively, this structure renders the capacitive sensor with a high sensitivity up to 143.5 MPa-1 at the pressure range of 0.068~150 kPa and excellent anti-fatigue performance over 20,000 cycles. Meanwhile, the sensor can distinguish different motions of the same person or different people doing the same action. Our work illustrates the promising application prospects of this flexible pressure sensor for the security field or human motion monitoring area.

Peeling Mode Capacitive Pressure Sensor for Sub-KPA Pressure Measurements

2006 ◽  
Author(s):  
Jeahyeong Han ◽  
Shunzhou Yang ◽  
Mark A. Shannon
Keyword(s):  
Residual Stresses ◽  
Pressure Sensor ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Capacitive Pressure Sensor ◽  
Resistance To Deformation ◽  
Fixed Electrode ◽  
Electrostatic Pressure ◽  
Nonlinear Signal ◽  
Low Pressures

Capacitive pressure sensors measure changes in pressure typically by the deflection of a flexible conducting membrane towards a fixed electrode. The deflection in the membrane produces a quadratic change in capacitance, which often yields higher sensitivity to changes in pressure compared to piezo-resistive pressure sensors, which measures the resistance changes proportional to the applied pressure. However, residual stresses in the membrane can provide a substantial resistance to deformation compared to the driving force created by the applied pressure, which decreases the sensitivity at low pressures and produces a nonlinear signal. If the membrane is made compliant enough to increase sensivitiy, pull-in of the membrane can occur, reducing the effective pressure range of the capacitive manometer type pressure sensor. Hence, these type of sensors are typically not used to measure very low pressure differences over several hundred Pascals. To overcome this limitation, a capacitive pressure sensor was developed that operates in a peeling mode while under applied electrostatic actuation, which counters the residual stresses. The changes in capacitance can be detected if the pressure is just enough to overcome the interfacial electrostatic pressure. This type of pressure sensor can potentially be used for very low differential pressure differences, well below 100 Pa, over ~ 1 kPa range.

scholarly journals Ultra-Sensitive Flexible Pressure Sensor Based on Microstructured Electrode

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 371 ◽  
Author(s):  
Mengmeng Li ◽  
Jiaming Liang ◽  
Xudong Wang ◽  
Min Zhang
Keyword(s):  
Pressure Sensor ◽  
Dielectric Layer ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Capacitive Sensor ◽  
Duty Ratio ◽  
Capacitive Pressure Sensor ◽  
Element Analysis ◽  
Sequential Coupling ◽  
Flexible Pressure Sensors

Flexible pressure sensors with a high sensitivity in the lower zone of a subtle-pressure regime has shown great potential in the fields of electronic skin, human–computer interaction, wearable devices, intelligent prosthesis, and medical health. Adding microstructures on the dielectric layer on a capacitive pressure sensor has become a common and effective approach to enhance the performance of flexible pressure sensors. Here, we propose a method to further dramatically increase the sensitivity by adding elastic pyramidal microstructures on one side of the electrode and using a thin layer of a dielectric in a capacitive sensor. The sensitivity of the proposed device has been improved from 3.1 to 70.6 kPa−1 compared to capacitive sensors having pyramidal microstructures in the same dimension on the dielectric layer. Moreover, a detection limit of 1 Pa was achieved. The finite element analysis performed based on electromechanical sequential coupling simulation for hyperelastic materials indicates that the microstructures on electrode are critical to achieve high sensitivity. The influence of the duty ratio of the micro-pyramids on the sensitivity of the sensor is analyzed by both simulation and experiment. The durability and robustness of the device was also demonstrated by pressure testing for 2000 cycles.

Silicon Carbide MEMS Capacitive Pressure Sensor for Harsh Environments

2013 ◽  
Author(s):  
Zhibang Chen ◽  
Wei Du ◽  
Feng Zhao
Keyword(s):  
Silicon Carbide ◽  
Pressure Sensor ◽  
Large Scale ◽  
Applied Pressure ◽  
High Sensitivity ◽  
Capacitive Pressure Sensor ◽  
Wide Range ◽  
Sensor Structure ◽  
Nuclear Station ◽  
Oil Gas

In this paper, we investigated a new capacitive pressure sensor structure on a silicon carbide (SiC) platform for high sensitivity and harsh environment operation capability. The superior material properties of SiC ensure robustness of the new sensor to withstand large-scale pressure at high temperature and in chemical/biological medium. The sensor structure consists of a circular SiC diaphragm suspended by four arms over a SiC substrate, with design to enable diaphragm to deflect nearly uniformly with applied pressure. This configuration results in improved sensing properties. With high sensitivity and operation capability in hostile environment, this new pressure sensor is promising for use in a wide range of applications such as automotive, nuclear station, aerospace, and oil/gas exploration, etc.

High sensitivity and broad detection range flexible capacitive pressure sensor based on rGO cotton fiber for human motion detection

2021 ◽  
Author(s):  
Rongliang Zheng ◽  
Youyuan Wang ◽  
Zhanxi Zhang ◽  
Yanfang Zhang ◽  
Jinzhan Liu
Keyword(s):  
Pressure Sensor ◽  
Cotton Fiber ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Human Motion ◽  
Superior Performance ◽  
Capacitive Pressure Sensor ◽  
Joint Movement ◽  
Process Technology ◽  
Flexible Pressure Sensors

Abstract Recently, flexible pressure sensors have attracted considerable interest in electronic skins, wearable devices, intelligent robots and biomedical diagnostics. However, the design of high sensitivity flexible pressure sensors often relies on expensive materials and complex process technology, which greatly limit their popularity and applications. Even worse, chemical-based sensors are poorly biocompatible and harmful to the environment. Here, we developed a flexible capacitive pressure sensor based on reduced graphene oxide (rGO) cotton fiber by a simple and low-cost preparation process. The environmentally friendly sensor exhibited a comprehensive performance with not only ultra-high sensitivity (up to 15.84 kPa-1) and a broad sensing range (0-500 kPa), but also excellent repeatability (over 400 cycles), low hysteresis (≤11.6%), low detection limit (<0.1 kPa) and wide frequency availability (sensitivity from 19.71 kPa-1 to 11.24 kPa-1, frequency from 100 Hz to 10 kHz). Based on its superior performance, the proposed sensor can detect various external stimuli (vertical stress, bending and airflow) and has been successfully applied for facial expression recognition, breathing detection, joint movement and walking detection, showing great potential for application in artificial electronic skin and wearable healthcare devices.

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