Piezoelectric Film Sensor Research Articles

Effect of Nearby Construction Activity on Endothelial Function, Sensitivity to Nitric Oxide, and Potassium Channel Activity in the Middle Cerebral Arteries of Rats.

The present study assessed the effect of nearby construction activity on the responses of rat middle cerebral arteries (MCA) to the endothelium-dependent vasodilator acetylcholine and the NO donor sodium nitroprusside (SNP) and the activity of MaxiK potassium channels in MCA smooth muscle cells from male Sprague-Dawley rats. Two monitoring systems were used to assess vibrations in the animal rooms during and immediately after construction activities near the research building where the animal facility is located. One was a commercially available system; the other was a Raspberry-Pi (RPi)-based vibration monitoring system designed in our laboratory that included a small computing unit attached to a rolling sensor (low sensitivity) and a piezoelectric film sensor (high sensitivity). Both systems recorded increased levels of vibration during construction activity outside the building. During the construction period, vasodilator responses to acetylcholine and SNP were abolished, and MaxiK single-channel current opening frequency and open-state probability in cell-attached patches of isolated MCA myocytes were dramatically decreased. Recovery of acetylcholine- and SNP-induced dilation was minimal in MCA from rats studied after completion of construction but housed in the animal facility during construction, whereas responses to acetylcholine and SNP were intact in rats purchased, housed, and studied after construction. Baseline levels of vibration returned after the completion of construction, concomitant with the recovery of normal endothelium-dependent vasodilation to acetylcholine and of NO sensitivity assessed by using SNP in MCA from animals obtained after construction. The results of this study indicate that the vibration associated with nearby construction can have highly disruptive effects on crucial physiologic phenotypes.

Vibration–Based online Tool Wear Monitoring Using Piezo Film Sensor Analyzed by I-kaz Multilevel Signal Feature

Wear in cutting tool is a normal phenomenon in machining process. Problems such as dimensional precision, surface finish quality and defect cost is due to the wear. The wear also can cause unexpected stop time and lower down the manufacturing productivity. Therefore, a system to monitor the progression of the tool wear is needed to predict the wear status and stop machining operation once the wear reach the allowed limit. In this study, the monitoring system was designed by utilizing 2 units of piezoelectric film sensors which are capable of detecting and analyzing signals related to tool holder vibration during the machining process in both feed and tangential axes. The sensors were stacked on x axis and z axis surfaces of the tool holder and signals were channeled to a charge amplifier and then to the digital data acquisition equipment which then display the vibration signal in time domain on the computer screen. A total of 8 experiments were carried out using CNC turning machine. Vibration signal and wear measurement were recorded for each run in the experiment. The experiment were stopped once the wear reach approximately 0.3mm. I-kaz multilevel signal features were extracted from the vibration signal recorded and then correlated with the flank wear status. There is a solid or substantial correlation between the cutting tool wear condition and I-kaz multilevel coefficient value, with average of 0.87 for I-kaz x coefficient (tangential direction) and 0.910 for I-kaz z coefficient (feed direction). This affirm that I-kaz multilevel signal feature can be assigned as the input criterion for the tool condition monitoring system that can estimate the current status of the flank wear on the cutting tools which can prevent defect in the machining process.

A Mattress System of Recognizing Sleep Postures Based on BCG Signal

Sleep posture recognition is the core index of diagnosis and treatment of positional sleep apnea syndrome. In order to detect body postures noninvasively, we developed a portable approach for sleep posture recognition using BCG signals with their morphological difference. A type of piezo-electric polymer film sensor was applied to the mattress to acquire BCG, the discrete wavelet transform with cubic B-spline was used to extract characteristic parameters and a naive Bayes learning phase was adapted to predict body postures. Eleven healthy subjects participated in the sleep simulation experiments. The results indicate that the mean error obtained from heart rates was 0.04±1.3 beats/min (±1.96 SD). The final recognition accuracy of four basic sleep postures exceeded 97%, and the average value was 97.9%. This measuring system is comfortable and accurate, which can be streamlined for daily sleep monitoring application.

A Flow Velocity Measurement Method Based on a PVDF Piezoelectric Sensor.

To measure the flow velocity of a fluid without affecting its motion state, a method was proposed based on a polyvinylidene fluoride (PVDF) piezoelectric film sensor. A self-made PVDF piezoelectric sensor placed parallel with the flow direction was used to measure the flow velocity. First, the piezoelectric characteristics of PVDF were obtained theoretically. Next, the relationship between flow velocity and sound pressure was verified numerically. Finally, the relationship between flow velocity and the electrical output of the PVDF piezoelectric film was obtained experimentally. In conclusion, the proposed method was shown to be reliable and effective.

Experimental and theoretical correlations for energy harvesting from a large flapping flag response

Two experimental models are constructed, i.e. partially covered and fully covered, cantilevered plates with piezoelectric piezo patches and film sensors. Two different experimental methods are used to obtain large flapping vibrations, a mechanically forced vibration and a limit cycle oscillation from an aeroelastic responses. AC voltage outputs from the piezo patch or film sensors and a DC power extraction through a AC/DC converter circuit are obtained. These experiments are used to evaluate a new computational model and code for a piezoelectric-aeroelastic system.

Space debris positioning based on two-dimensional PVDF piezoelectric film sensor

In order to determine the positions of debris collision spacecraft accurately, the experiments have been performed to impact orthogonal stacking two-dimensional Polyvinylidene fluoride (PVDF) piezoelectric film at different collision speeds based on the piezoelectric effects of the PVDF film by using two-stage light gas gun loading system and the self-constructed positioning system. The debris source was positioned accurately by PVDF strips sensor and testing system, which has been established to extract piezoelectric signals of the PVDF film during the process of impacting. The visualization of the position for debris impacting spacecraft was achieved through the LABview language programme and signal processing acquired by the signal acquisition system in the experiments. The experimental results show that the positions of the debris impacting source can be realized accurately by the piezoelectric effects of the orthogonal stacking two-dimensional PVDF film, the flight velocity and the incidence angle of the debris can be determined by installing the double-set PVDF film as the targets with a certain spacing.

Experimental investigation on the suitability of flexible pressure sensor for wrist pulse measurement

Pulse examination at the radial artery of the wrist is a most apparent diagnosis technique. Wrist pulse carries rich information about the cardiovascular system of human body. An investigation is made here to suggest suitable flexible type of thin film pressure sensor to measure the wrist pulse as per Ayurvedic medicine system. Primary objective of this work is to suggest a sensor which exhibits optimum spatial features and SNR values. Force Sensing Resistor (FSR), piezoresistive and piezoelectric thin film sensors are considered under this study. Piezoelectric sensor shows good performance in the quality of the pulse with 22 dB SNR. Further experimentation is conducted to find out transmissivity, repeatability and susceptibility to motion artifact. Trasnsmissivities of 0.91, 0.68 and 0.64 are obtained for piezoelectric, piezoresistive and FSR sensors respectively. Piezoresistive and FSR show repeatability error of ±8% and ± 7% while measuring pulse amplitude under standard force. Noise due to motion artifact for each type of sensors are recorded and compared with the standard Gaussian distribution function with the help of histogram. Collectively, piezoelectric sensor exhibits good spatial features, high transmissivity and comparatively low susceptibility to motion artifact.

Microanalysis and Piezoelectric Properties Study of Piezoelectric Film Sensors Based on Heat Treatment Process

Microanalysis and Piezoelectric Properties Study of Piezoelectric Film Sensors Based on Heat Treatment Process

Analysis of skeletal muscle performance using piezoelectric film sensors.

A flexible piezoelectric thin film sensor has been proposed recently in several studies for detection of muscle movements. The objective of this study was to investigate the ability of this sensor to assess skeletal muscle performance and fatigue under isokinetic contractions. Simultaneous noninvasive measurements of muscles activity were done using surface electromyography (EMG) electrodes and two thin film piezoelectric sensors. Measurements were taken from the biceps during slow and fast elbow flexion with and without strong grip, during different weight lifting and from the gastrocnemius during treadmill marching at speeds of 4 and of 10 kph. The results shows correlation between the onset of EMG and the piezoelectric sensors (Piezo) signals during muscle contraction. Increasing contraction intensity increase significantly both EMG and Piezo signals. Higher contractions velocity increased Piezo signal. Opposite linear relation was found between the average maximal EMG envelope amplitudes and the average maximal Piezo peaks with increasing loads. The significant decrease in the maximal Piezo peaks with time of all 3 subjects during elbow flexion while holding weight suggests the ability of piezoelectric thin film sensor to track muscle fatigue during isokinetic contractions.

COMPARISON STUDY ON LIGHT STRUCTURE MODAL PARAMETER USING EXPERIMENTAL MODAL ANALYSIS METHOD VIA PIEZOFILM SENSOR

This study determines the effect of modal parameters namely natural frequencies and mode shapes of aluminum 6061 (Al6061)through free dynamic vibration analysis and testing. The simulation procedures was conducted via ANSYS software while the experimental work was performed through impact hammer testing. Three types of specimens in the form of circular, square and triangular- shapes were used to determine the vibration parameters. Two sensors i.e. piezoelectric film and accelerometer were used. The results for circular shape were ya = 270.55x – 134.82 (accelerometer) and yp = 280.89x – 215.05 (piezofilm); for square shape were ya = 316.42x – 104.13 (accelerometer) and yp = 309.63x – 43.20 (piezofilm); and for triangular shape were ya = 329.77x – 142.87 (accelerometer) and yp = 305x + 15 (piezofilm). The ya (accelerometer) and yp (piezofilm) are represented as a linear equation of which the data were plotted in mode shape versus natural frequency graph accordingly. By applying the simultaneous equation, the regression ratio can be obtained. The relation between natural frequency and mode shape of accelerometer and piezofilm for the circular-shaped specimen was ya = 0.96yp + 72.3; square-shaped specimen was ya = 1.02yp – 59.98; and triangle-shaped specimen was ya = 1.08yp – 159.08 respectively. The results for the natural frequency from the experimental test were used to compare with the results from the simulation. It was understood that the regression ratios of 0.96, 1.02 and 1.08 of circular-shaped, square-shaped and triangular-shaped were closed to 1.0. The outcome showed that the piezoelectric film sensor is a potential candidate to be used as an alternative sensor for the accelerometer.

Thermal conductivity of PVDF/PANI-nanofiber composite membrane aligned in an electric field

Poly(vinylidene fluoride) (PVDF) is a semi-crystalline thermoplastic polymer with excellent thermal stability, electrochemical stability and corrosion resistance, which has been widely studied and applied in industrial nonmetallic heat exchanger and piezoelectric-film sensor. In this study, polyaniline (PANI) nanofibers were synthesized using dodecylbenzene sulfonic acid as the surfactant. The obtained PANI nanofibers were blended in PVDF matrix to enhance thermal conductivity and tensile strength of composite materials. Electric field was applied for the orientation of membrane structure during membrane formation. Scanning electron microscope (SEM) images exhibited that the PANI nanofibers were well-dispersed in the composite membranes. The structure of composite membranes was more orderly after alignment. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) indicated that the content of PANI nanofibers contributed to the transformation of PVDF from α-phase to β-phase. Both the tensile strength and thermal conductivity of composite membranes were significantly improved. This tendency was further enhanced by the application of electric field. The maximum tensile strength was obtained when the content of PANI nanofibers was 3 wt%, which was 46.44% higher than that of pure PVDF membrane. The maximum thermal conductivity of composite membranes after alignment was 84.5% greater than that of pure PVDF membrane when the content of PANI nanofibers was 50 wt%. The composite membrane is a promising new potential material in heat transfer field and the mechanism explored in this study would be informative for further development of similar thermal conductive polymeric materials.

Performance of a new piezoceramic thick film sensor for measurement and control of cutting forces during milling

Process monitoring and controlling with detailed real-time information such as the cutting force is required for improving the performance of milling processes. This paper presents a novel system for measuring the cutting force in the direct vicinity of the indexable insert. The outlined concept makes use of piezoelectric thick film sensors mounted directly below the insert. The unique design and features of the new sensor enable accurate and continuous force measurements as well as the indication of wear. The results of the experimental investigations are presented and compared to results of a conventional dynamometer.

Facile Fabrication of a Flexible LiNbO3 Piezoelectric Sensor through Hot Pressing for Biomechanical Monitoring.

Wearable pressure sensors have attracted increasing attention for biomechanical monitoring due to their portability and flexibility. Although great advances have been made, there are no facile methods to produce sensors with good performance. Here, we present a simple method for manufacturing flexible and self-powered piezoelectric sensors based on LiNbO3 (LN) particles. The LN particles are dispersed in polypropylene (PP) doped with multiwalled carbon nanotubes (MWCNTs) by hot pressing (200 °C) to form a flexible LN/MWCNT/PP piezoelectric composite film (PCF) sensor. This cost-effective sensor has high sensitivity (8 Pa), fast response time (ca. 40 ms), and long-term stability (>3000 cycles). Measurements of pressure changes from peripheral arteries demonstrate the applicability of the LN/MWCNT/PP PCF sensor to biomechanical monitoring as well as its potential for biomechanics-related clinical diagnosis and forecasting.

AN INVESTIGATION ON LIGHT STRUCTURE MODAL PARAMETER BY USING EXPERIMENTAL MODAL ANALYSIS METHOD VIA PIEZOFILM SENSOR

This study is conducted to determine the modal parameters namely natural frequencies and mode shapes of aluminum 6061 (Al6061). The parameters are done by conducting a free dynamic vibration analysis. Modal analysis study was conducted by both simulation and experimental approaches. The simulation was conducted via ANSYS software while the experimental work was performed through impact hammer testing to determine the vibration parameter. Two sensors i.e. piezoelectric film and accelerometer were used. The result obtained were ya = 302.02x – 52.51 (accelerometer) and yp = 295.78x - 41.73 (piezofilm). ya (accelerometer) and yp (piezofilm) is linear equation of the data plotted according to the reading from mode shape versus natural frequency. The relation between natural frequency from accelerometer and piezofilm for the rectangular-shaped specimen was ya = 1.02yp – 9.90 and can be concluded that the regression ratio of 1.02 was approximately 1.0 which agreed with the status of piezoelectric film sensor that can be used as an alternative sensor for accelerometer. There was a good results agreement between simulation and experimental work outcome.

NOVEL TECHNIQUE OF MODAL ANALYSIS FOR LIGHT STRUCTURE VIA PIEZOFILM SENSOR: A COMPARISON STUDY

This study is conducted to determine the modal parameters namely natural frequencies and mode shapes of aluminum 6061 (Al6061). A light and small structure made from Al6061 is chosen as the experimental specimen mainly because of its wide application in industries such as automotive parts or accessories and robotic, mainly in manufacturing of automobile frames. If a component vibrates with a frequency that is coherent with the component’s natural frequency, resonance frequency will occur and structural failure might emerge. Two sensors i.e. piezoelectric film and accelerometer were used. The result obtained were ya = 329.60x – 142.27 (accelerometer) and yp = 304.98x + 15.18 (piezofilm). The relation between natural frequency of accelerometer and piezofilm for the triangle-shape specimen was ya = 1.08yp – 158.67 and can be concluded that the regression ratio of 1.08 was approximately 1.0 which agreed with the status of piezoelectric film sensor that can be used as an alternative sensor for accelerometer. There was a good results agreement between simulation and experimental work outcome.Â

Low-power, noninvasive measurement system for wearable ballistocardiography in sitting and standing positions

Ballistocardiography (BCG), the noninvasive measurement of the reaction forces of the body to the cardiac ejection of blood, is one of few methods available for unobtrusively assessing the mechanical aspects of cardiovascular health outside clinical settings. In this study, two sizes of piezoelectric film sensors were installed into the seat cushion of a chair and the foot insole, respectively, to acquire local BCG signals in sitting and standing positions. The design and engineering implementation of the signal processing circuit and data transmission system are discussed below. Although wearable BCG measurement devices have been extensively researched to date, to the authors’ knowledge, they have never been tested in regards to power consumption and electrostatic discharge (ESD) immunity. In this work, comprehensive experiments were conducted to show the low power consumption and high reliability of the proposed system. The shapes and the amplitudes of measured signals were examined in detail. The results suggest that the proposed system can feasibly and reliably be used to continuously record and evaluate cardiovascular changes occurring throughout an individual’s daily life.

嚥下計測用センサシステムに関する研究

The accidental swallowing caused by decline of the ability to swallow due to aging is a severe problem for elder people. Therefore, effective methods of monitoring swallowing action and estimating swallowing function are required. In this paper, a piezoelectric film sensor is developed to estimate the swallowing function. To investigate the relationship between swallowing action and sensor output behavior, pharynx movement is measured by using the piezoelectric film sensor and three-dimensional motion analysis system. In experiments, we measured the swallowing action during repetitive saliva swallowing test that is a major screening test for dysphagia by using the developed sensor system. As a result, it is found that number of swallowing can be evaluated by using the standard deviation of the developed sensor output.

System of GIS Flashover Accident Based on Vibration Method

Gas-insulated metal enclosed switchgear (GIS) improved the security of EHV transmission applications, which was used more and more widely in recent years in the power system. However, due to the internal insulation defects of the GIS may cause GIS flashover accident, at present, it has studied discharge breakdown by more research for a long time both at home and abroad, which makes reference to the study of fast discharge breakdown caused by flashover, it caused great harm and easy to cause the smart grid paralysis, it should be timely quickly repaired. Based on Piezoelectric film sensors, STM32F3 microcontroller and ZigBee networking technology, this paper designed the GIS flashover quickly locating Scheme based on method of vibration, which achieved the expected flashover fast fault location function, and has a small size, easy operation and low cost advantages.

C-axis tilted ScAlN shear wave acoustic Bragg reflect resonator for gigahertz viscosity measurement

c-axis tilted ScAlN film is attractive for resonators exciting shear wave ultrasonic. Shear mode resonators are suitable for biomarker sensing and viscosity sensing because shear mode resonators can operate without energy leakage to liquid. These sensors are well known as a QCM (Quartz Crystal Microbalance) consisting of AT-cut quartz crystal which excites shear wave ultrasonic. When the resonator is immersed in liquid, resonant frequency decreases due to the viscosity perturbation layer between the resonator and liquid interface. The rate of resonant frequency decrease depend on the mass ratio of viscosity perturbation layer and the resonator layer. Therefore, thinner high frequency resonator allows high sensitivity viscosity measurement. The maximum resonant frequency of the standard QCM plate is about 30 MHz. On the other hand, c-axis tilted ScAlN film can operates over 1 GHz. The sensitivity of the piezoelectric film sensors are much higher thanthat of the QCM sensors. In this study, we deposited shea...

Design of efficient loadcell for measurement of mechanical impact by piezoelectric PVDF film sensor

Conversion efficiency of mechanical impact into electrical voltage remains ever increasing demand for piezoelectric PVDF film sensor. For a given film sensor, the output voltage produced due to mechanical impact is highly dependent on the direction of stretching (or compressing) and active area of the film sensor. More is the active area of the film; higher will be the output voltage. It is shown that the active area is significantly increased due to the ridge-like shape given at the inner surfaces of the plates of sandwich type loadcell and as a result of which higher conversion efficiency is obtained. The effectiveness of the ridge-like shape is confirmed statistically by conducting two factorial design of experiment in which shape and material of the loadcell are considered as the two factors with 2×4 matrix. In case of loadcell made of glass plates, more than 100% increase in the output voltage is observed for ridge-like shape in comparison to its plain counterpart. Both the bandwidth and frequency range of the output signal is found to be independent and dependent of the loadcell materials for indirect and direct impact with the loadcell respectively. The merits and demerits of the fabricated loadcells are discussed.