scholarly journals Novel Flexible PVDF-TrFE and PVDF-TrFE/ZnO Pressure Sensor: Fabrication, Characterization and Investigation

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 602
Author(s):  
Mingran Liu ◽  
Yang Liu ◽  
Limin Zhou
Keyword(s):  
Pressure Sensor ◽  
Vinylidene Fluoride ◽  
Pressure Sensors ◽  
Weight Ratio ◽  
Composite Membranes ◽  
Annealing Process ◽  
Voltage Response ◽  
Electrical Signals ◽  
Β Phase ◽  
Phase Crystal

With the development of human healthcare devices, smart sensors, e-skins, and pressure sensors with outstanding sensitivity, flexibility, durability and biocompatibility have attracted more and more attention. In this paper, to develop a novel flexible pressure sensor with high sensitivity, different poly (vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)-based composite membranes were fabricated, characterized and tested. To improve the β-phase crystallinity and piezoelectricity of the membranes, and for the purpose of comparison, nano ZnO particles with different concentrations (99:1, 9:1 in a weight ratio of PVDF-TrFE to ZnO) were, respectively added into PVDF-TrFE polymer acting as a nucleating agent and dielectric material. To facilitate the formation of β-phase crystal, the membranes were fabricated by electrospinning method. After the electrospinning, an annealing process was conducted to the fabricated membranes to increase the size and content of β-phase crystal. Then, the fabricated PVDF-TrFE membranes, acting as the core sensing layer, were, respectively built into multiple prototype sensors in a sandwich structure. The sensitivity of the prototype sensors was tested by an auto-clicker. The stimulation of the auto-clicker on the prototype sensors generated electrical signals, and the electrical signals were collected by a self-built testing platform powered by LabVIEW. As a result, combining the addition of ZnO nanofillers and the annealing process, a highly sensitive pressure sensor was fabricated. The optimal peak-to-peak voltage response generated from the prototype sensor was 1.788 V which shows a 75% increase compared to that of the pristine PVDF-TrFE sensor. Furthermore, a human pulse waveform was captured by a prototype sensor which exhibits tremendous prospects for application in healthcare devices.

scholarly journals Enhancement of β-Phase Crystal Content of Poly(vinylidene fluoride) Nanofiber Web by Graphene and Electrospinning Parameters

2020 ◽  
Vol 38 (11) ◽  
pp. 1239-1247 ◽  
Author(s):  
Lu Jin ◽  
Yan Zheng ◽  
Ze-Kun Liu ◽  
Jia-Shen Li ◽  
Yang-Pei-Qi Yi ◽  
...  
Keyword(s):  
Vinylidene Fluoride ◽  
Β Phase ◽  
Phase Crystal ◽  
Poly Vinylidene Fluoride ◽  
Nanofiber Web ◽  
Crystal Content

The Effects of Additive Manufacturing and Electric Poling Techniques on PVdF Thin Films: Towards 3D Printed Functional Materials

2020 ◽  
Author(s):  
Jinsheng Fan ◽  
David Gonzalez ◽  
Jose Garcia ◽  
Brittany Newell ◽  
Robert A. Nawrocki
Keyword(s):  
Thin Films ◽  
Smart Materials ◽  
Vinylidene Fluoride ◽  
Pressure Sensors ◽  
Functional Materials ◽  
Piezoelectric Constant ◽  
Β Phase ◽  
Calibration Curves ◽  
Wide Range ◽  
3D Printed

Abstract Mechanical flexibility, faster processing, lower fabrication cost and biocompatibility enable poly (vinylidene fluoride) (PVdF) to have a wide range of applications. This work investigated the use of a piezoelectric polymeric material, PVdF, in combination with 3D printing, to explore new strategies for the fabrication of smart materials with embedded functions, namely sensing. The motivation behind this research was to design and fabricate PVdF thin films that will be used to build pressure sensors with applications in active intelligent structures. In this work, 3D printed PVdF thin films with thickness values in the range of 250 to 350 μm were poled under high direct current electrical fields, which were varied from 0.4 to 12 MV/m and temperatures from 80 to 140 °C. Copper electrodes were applied, forming a standard capacitor layered structure, to facilitate poling and to collect piezoelectric output voltage. The poling process enabled the piezoelectric crystalline phase transition of printed PVdF films to transfer from the non-active a α-phase to the piezoelectric active β-phase and rearranged the dipole alignments of the β-phase. The efficiency of poling was evaluated through the piezoelectric constant calculated from measured calibration curves. These calibration curves demonstrated the PVdF sensing device have a positive linear correlation between mechanical input and voltage output. We found that a peak value in piezoelectric constant correlated with poling voltages and temperatures. The highest piezoelectric constant achieved through contact poling was 32.29 pC/N poled at 750 V and 120 °C, and temperature was deemed the most important factors to influence piezoelectric constant. We believe that the present work demonstrates a path towards fully 3D printed smart, functional materials.

Zinc oxide nanorod as effective reinforcing material for enhancing β phase crystal in poly(vinylidene fluoride) filaments

2020 ◽  
Vol 54 (25) ◽  
pp. 3833-3839
Author(s):  
Prasanta K Panda ◽  
Sachin R Tambe ◽  
Amol G Thite
Keyword(s):  
Zinc Oxide ◽  
Draw Ratio ◽  
Vinylidene Fluoride ◽  
Zinc Oxide Nanorods ◽  
Melt Compounding ◽  
Β Phase ◽  
Oxide Nanorods ◽  
Phase Crystal ◽  
Poly Vinylidene Fluoride ◽  
Crystal Content

The present work is an attempt to demonstrate that incorporation of small amount of zinc oxide nanorods enhances the β crystal percentage, which is essential for improvement in piezo-electric performance of the poly(vinylidene fluoride) (PVDF) fiber. The zinc oxide nanorods were synthesized with aspect ratio of 26 and uniformly dispersed in PVDF by melt compounding process. Those compounded polymers were melt spun and subsequently cold drawn to obtain composite filaments. The effect of nanostructure, loading amount, melt draw ratio, cold draw ratio, and drawing temperature was investigated. The incorporation of nanorods resulted in 14% increase in β phase crystal content compared to control PVDF filaments. The β phase crystal content has been analyzed using the wide-angle X ray diffraction and FTIR spectroscopy. This increase in β phase crystal content was 10% more compared to circular zinc oxide nanoparticle reinforced PVDF composite filament. There was no significant change in mechanical properties of the composite filaments compared to the control PVDF filament.

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.

Dielectric Behavior of PVDF/PP-PT Nanocomposite Thin Films

2014 ◽  
Vol 1002 ◽  
pp. 11-16
Author(s):  
Ting Ting Yu ◽  
Zhao Hui Ren ◽  
Si Min Yin ◽  
Xin Yang ◽  
Yi Feng Yu ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Low Frequency ◽  
Weight Ratio ◽  
Dielectric Behavior ◽  
Β Phase ◽  
Nanocomposite Thin Films ◽  
Coating Method

PVA/PVP-assisted hydrothermal method was used to prepare single-crystal pre-perovskite PbTiO3(PP-PT) nanofibers, in which polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) acted as surfactants. Subsequently, poly (vinylidene fluoride)/ pre-perovskite PbTiO3nanofibers (PVDF/PP-PT) nanocomposite thin films were successfully fabricated by a spin-coating method. The test results showed that PP-PT nanofibers had a good distribution in PVDF matrix. Moreover, α-phase coexisted with β-phase in the PVDF and PVDF/PP-PT nanocomposite thin films. The dielectric properties of the PVDF/PP-PT nanocomposite thin films were measured as a function of frequency in the range of 5 kHz to 5 MHz. It is worth noting that the dielectric constant of nanocomposite thin films increased with increasing the weight ratio of PP-PT nanofibers in the low frequency range. By contrast, the dielectric constant of PVDF/PP-PT nanocomposite thin film which contained 20% PP-PT nanofibers was 43.7% larger than that of pure PVDF thin film (εr= 6.77) at 5 kHz, and the loss tangent was ~0.03.

scholarly journals Piezoelastic PVDF/TPU Nanofibrous Composite Membrane: Fabrication and Characterization

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1634 ◽  
Author(s):  
Eman Elnabawy ◽  
Ahmed H. Hassanain ◽  
Nader Shehata ◽  
Anton Popelka ◽  
Remya Nair ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Vinylidene Fluoride ◽  
Thermoplastic Polyurethane ◽  
Weight Ratio ◽  
Composite Membranes ◽  
Piezoelectric Response ◽  
Wearable Electronics ◽  
Electric Voltage ◽  
The Impact ◽  
Piezoelectric Characteristics

Poly (vinylidene fluoride) nanofibers (PVDF NFs) have been extensively used in energy harvesting applications due to their promising piezoresponse characteristics. However, the mechanical properties of the generated fibers are still lacking. Therefore, we are presenting in this work a promising improvement in the elasticity properties of PVDF nanofibrous membrane through thermoplastic polyurethane (TPU) additives. Morphological, physical, and mechanical analyses were performed for membranes developed from different blend ratios. Then, the impact of added weight ratio of TPU on the piezoelectric response of the formed nanofibrous composite membranes was studied. The piezoelectric characteristics were studied through impulse loading testing where the electric voltage had been detected under applied mass weights. Piezoelectric characteristics were investigated further through a pressure mode test the developed nanofibrous composite membranes were found to be mechanically deformed under applied electric potential. This work introduces promising high elastic piezoelectric materials that can be used in a wide variety of applications including energy harvesting, wearable electronics, self-cleaning filters, and motion/vibration sensors.

scholarly journals Self-Powered Wearable Pressure Sensors with Enhanced Piezoelectric Properties of Aligned P(VDF-TrFE)/MWCNT Composites for Monitoring Human Physiological and Muscle Motion Signs

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1021 ◽  
Author(s):  
Aochen Wang ◽  
Ming Hu ◽  
Liwei Zhou ◽  
Xiaoyong Qiang
Keyword(s):  
Composite Membrane ◽  
Pressure Sensor ◽  
Vinylidene Fluoride ◽  
Positive Impact ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Electrospinning Process ◽  
Mechanical Stimuli ◽  
Self Powered ◽  
Piezoelectric Pressure Sensor

Self-powered operation, flexibility, excellent mechanical properties, and ultra-high sensitivity are highly desired properties for pressure sensors in human health monitoring and anthropomorphic robotic systems. Piezoelectric pressure sensors, with enhanced electromechanical performance to effectively distinguish multiple mechanical stimuli (including pressing, stretching, bending, and twisting), have attracted interest to precisely acquire the weak signals of the human body. In this work, we prepared a poly(vinylidene fluoride-trifluoroethylene)/ multi-walled carbon nanotube (P(VDF-TrFE)/MWCNT) composite by an electrospinning process and stretched it to achieve alignment of the polymer chains. The composite membrane demonstrated excellent piezoelectricy, favorable mechanical strength, and high sensitivity. The piezoelectric coefficient d33 value was approximately 50 pm/V, the Young’s modulus was ~0.986 GPa, and the sensitivity was ~540 mV/N. The resulting composite membrane was employed as a piezoelectric pressure sensor to monitor small physiological signals including pulse, breath, and small motions of muscle and joints such as swallowing, chewing, and finger and wrist movements. Moderate doping with carbon nanotubes had a positive impact on the formation of the β phase of the piezoelectric device, and the piezoelectric pressure sensor has the potential for application in health care systems and smart wearable devices.

Flexible pressure sensor with a “V-type” array microelectrode on a grating PDMS substrate

Sensor Review ◽  
2016 ◽  
Vol 36 (4) ◽  
pp. 397-404 ◽  
Author(s):  
Jianli Cui ◽  
Junping Duan ◽  
Binzhen Zhang ◽  
Xueli Nan
Keyword(s):  
Pressure Sensor ◽  
Nanoimprint Lithography ◽  
Pressure Sensors ◽  
Weight Ratio ◽  
Master Mold ◽  
Pdms Substrate ◽  
Cycle Stability ◽  
Molding Process ◽  
Content Type ◽  
Array Structure

Purpose This paper aims to provide a fabrication and measurement of a highly stretchable pressure sensor with a “V-type” array microelectrode on a grating PDMS substrate. Design/methodology/approach First, the “V-type” array structure on the silicon wafer was fabricated by the MEMS technology, and the fabrication process included ultra-violet lithography and silicon etching. The “V-type” array structure on the master mold was then replicated into polycarbonate, which served as an intermediate, negative mold, using a conventional nanoimprint lithography technique. The negative mold was subsequently used in the PDMS molding process to produce PDMS “V-type” array structures with the same structures as the master mold. An Ag film was coated on the PDMS “V-type” array structure surface by the magnetron sputtering process to obtain PDMS “V-type” array microelectrodes. Finally, a PDMS prepolymer was prepared using a Sylgard184 curing agent with a weight ratio of a 20:1 and applied to the cavity at the middle of the two-layer PDMS “V-type” array microelectrode template to complete hot-press bonding, and a pressure sensor was realized. Findings The experimental results showed that the PDMS “V-type” array microelectrode has high stretchability of 65 per cent, temperature stability of 0.0248, humidity stability of 0.000204, bending stability and cycle stability. Capacitive pressure sensors with a “V-type” array microelectrode exhibit ideal initial capacitance (111.45 pF), good pressure sensitivity of 0.1143 MPa-1 (0-0.35 Mpa), fast response and relaxation times (<200 ms), high bending stability, high temperature/humidity stability and high cycle stability. Originality/value The PDMS “V-type” array structure microelectrode can be used to fabricate pressure sensors and is highly flexible, crack-free and durable.

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 Simulation and Nonlinearity Optimization of a High-Pressure Sensor

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4419
Author(s):  
Ting Li ◽  
Haiping Shang ◽  
Weibing Wang
Keyword(s):  
High Pressure ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Original Model ◽  
Ansys Software ◽  
Nonlinear Error ◽  
Sensor Model ◽  
Optimized Model ◽  
Simulation Results ◽  
Better Than

A pressure sensor in the range of 0–120 MPa with a square diaphragm was designed and fabricated, which was isolated by the oil-filled package. The nonlinearity of the device without circuit compensation is better than 0.4%, and the accuracy is 0.43%. This sensor model was simulated by ANSYS software. Based on this model, we simulated the output voltage and nonlinearity when piezoresistors locations change. The simulation results showed that as the stress of the longitudinal resistor (RL) was increased compared to the transverse resistor (RT), the nonlinear error of the pressure sensor would first decrease to about 0 and then increase. The theoretical calculation and mathematical fitting were given to this phenomenon. Based on this discovery, a method for optimizing the nonlinearity of high-pressure sensors while ensuring the maximum sensitivity was proposed. In the simulation, the output of the optimized model had a significant improvement over the original model, and the nonlinear error significantly decreased from 0.106% to 0.0000713%.

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