Showing papers on "Piezoelectric sensor published in 2021"

Sensitive, small, broadband and scalable optomechanical ultrasound sensor in silicon photonics

Abstract: Ultrasonography1 and photoacoustic2,3 (optoacoustic) tomography have recently seen great advances in hardware and algorithms. However, current high-end systems still use a matrix of piezoelectric sensor elements, and new applications require sensors with high sensitivity, broadband detection, small size and scalability to a fine-pitch matrix. This work demonstrates an ultrasound sensor in silicon photonic technology with extreme sensitivity owing to an innovative optomechanical waveguide. This waveguide has a tiny 15 nm air gap between two movable parts, which we fabricated using new CMOS-compatible processing. The 20 μm small sensor has a noise equivalent pressure below 1.3 mPa Hz−1/2 in the measured range of 3–30 MHz, dominated by acoustomechanical noise. This is two orders of magnitude better than for piezoelectric elements of an identical size4. The demonstrated sensor matrix with on-chip photonic multiplexing5–7 offers the prospect of miniaturized catheters that have sensor matrices interrogated using just a few optical fibres, unlike piezoelectric sensors that typically use an electrical connection for each element. An optical ultrasound sensor based on a CMOS-compatible split-rib waveguide is demonstrated, offering high sensitivity, broadband detection (measured 3–30 MHz), small size (20 μm) and scalability to a fine-pitch matrix.

Skin-Inspired Piezoelectric Tactile Sensor Array with Crosstalk-Free Row+Column Electrodes for Spatiotemporally Distinguishing Diverse Stimuli

Abstract: Real-time detection and differentiation of diverse external stimuli with one tactile senor remains a huge challenge and largely restricts the development of electronic skins. Although different sensors have been described based on piezoresistivity, capacitance, and triboelectricity, and these devices are promising for tactile systems, there are few, if any, piezoelectric sensors to be able to distinguish diverse stimuli in real time. Here, a human skin-inspired piezoelectric tactile sensor array constructed with a multilayer structure and row+column electrodes is reported. Integrated with a signal processor and a logical algorithm, the tactile sensor array achieves to sense and distinguish the magnitude, positions, and modes of diverse external stimuli, including gentle slipping, touching, and bending, in real time. Besides, the unique design overcomes the crosstalk issues existing in other sensors. Pressure sensing and bending sensing tests show that the proposed tactile sensor array possesses the characteristics of high sensitivity (7.7 mV kPa-1), long-term durability (80 000 cycles), and rapid response time (10 ms) (less than human skin). The tactile sensor array also shows a superior scalability and ease of massive fabrication. Its ability of real-time detection and differentiation of diverse stimuli for health monitoring, detection of animal movements, and robots is demonstrated.

Hierarchical PVDF-HFP/ZnO composite nanofiber–based highly sensitive piezoelectric sensor for wireless workout monitoring

Abstract: High sensitivity of sensors is extremely significant for precisely monitoring imperceptible changes of motion in real-time, which cannot be achieved by traditional piezoelectric devices. Herein, a hierarchical polyvinylidene fluoride hexafluoropropylene (PVDF-HFP)/ZnO composite nanaofiber piezoelectric sensor with highly sensitivity has been prepared through epitaxial growing ZnO nanosheets on the surface of electrospun PVDF-HFP nanofibers. Systematic investigations have shown that their optimum pressure sensing performance with a sensitivity of 1.9 V kPa−1 and a short response time of 20 ms are achieved for forces from 0.02 to 0.5 N with excellent durability and stability up to 5000 cycles. Moreover, this sensor can precisely detect the imperceptible changes in player’s motions to avoid injury from overtraining. Additionally, a Bluetooth-low-energy that tracks player’s workout and transmits the output signals wirelessly to a smartphone app is utilized. The study provides a feasible approach for high-precision detecting and safety monitoring in the fields of medical, rehabilitation medicine, and workout security.

Superflexible and Lead-Free Piezoelectric Nanogenerator as a Highly Sensitive Self-Powered Sensor for Human Motion Monitoring

Abstract: For traditional piezoelectric sensors based on poled ceramics, a low curie temperature (Tc) is a fatal flaw due to the depolarization phenomenon. However, in this study, we find the low Tc would be a benefit for flexible piezoelectric sensors because small alterations of force trigger large changes in polarization. BaTi0.88Sn0.12O3 (BTS) with high piezoelectric coefficient and low Tc close to human body temperature is taken as an example for materials of this kind. Continuous piezoelectric BTS films were deposited on the flexible glass fiber fabrics (GFF), self-powered sensors based on the ultra-thin, superflexible, and polarization-free BTS-GFF/PVDF composite piezoelectric films are used for human motion sensing. In the low force region (1–9 N), the sensors have the outstanding performance with voltage sensitivity of 1.23 V N−1 and current sensitivity of 41.0 nA N−1. The BTS-GFF/PVDF sensors can be used to detect the tiny forces of falling water drops, finger joint motion, tiny surface deformation, and fatigue driving with high sensitivity. This work provides a new paradigm for the preparation of superflexible, highly sensitive and wearable self-powered piezoelectric sensors, and this kind of sensors will have a broad application prospect in the fields of medical rehabilitation, human motion monitoring, and intelligent robot.

Asymmetric 2D MoS2 for Scalable and High-Performance Piezoelectric Sensors.

Abstract: Piezoelectricity in two-dimensional (2D) transition-metal dichalcogenides (TMDs) has attracted significant attention due to their unique crystal structure and the lack of inversion centers when the bulk TMDs thin down to monolayers. Although the piezoelectric effect in atomic-thickness TMDs has been reported earlier, they are exfoliated 2D TMDs and are therefore not scalable. Here, we demonstrate a superior piezoelectric effect from large-scale sputtered, asymmetric 2D MoS2 using meticulous defect engineering based on the thermal-solvent annealing of the MoS2 layer. This yields an output peak current and voltage of 20 pA and 700 mV (after annealing at 450 °C), respectively, which is the highest piezoelectric strength ever reported in 2D MoS2. Indeed, the piezoelectric strength increases with the defect density (sulfur vacancies), which, in turn, increases with the annealing temperature at least up to 450 °C. Moreover, our piezoelectric MoS2 device array shows an exceptional piezoelectric sensitivity of 262 mV/kPa with a high level of uniformity and excellent performance under ambient conditions. A detailed study of the sulfur vacancy-dependent property and its resultant asymmetric structure-induced piezoelectricity is reported. The proposed approach is scalable and can produce advanced materials for flexible piezoelectric devices to be used in emerging bioinspired robotics and biomedical applications.

The frequency-response behaviour of flexible piezoelectric devices for detecting the magnitude and loading rate of stimuli

Abstract: Piezoelectric sensors with good flexibility and high sensitivity have attracted extensive interest in wearable electronics. Here, we report a novel frequency-response behaviour of piezoelectric voltage of a sensor that is based on a piezoelectric enhanced composite film of P(VDF-TrFE) and BaTiO3. The piezoelectric voltage enhances with the increase of frequency and becomes stable beyond the critical frequency. Such a demonstrated sensing characteristic of the piezoelectric sensor depends on the inner resistance of the voltmeter, which is determined by whether the loading of stimuli can be completed within the period of piezoelectric voltage measurement in the testing circuit. By utilizing the frequency-response behaviour in different frequency ranges, the flexible piezoelectric device exhibits excellent capabilities to quantitatively detect the magnitude and loading rate of stimuli. As a proof-of-concept demonstration, a flexible pressure sensor is successfully integrated with a bionic bee to monitor the flight status (i.e., strain rate and strain) of the vibrating wings. This work demonstrates that flexible piezoelectric sensors have great prospects for application in the field of bionic flying robots, thus paving the way forward for the development of smart self-sensing flexible electronics.

One-Step Preparation of a Core-Spun Cu/P(VDF-TrFE) Nanofibrous Yarn for Wearable Smart Textile to Monitor Human Movement.

Abstract: At present, wearable electronic sensors are widely investigated and applied for human life usage especially for the flexible piezoelectric sensor based on piezoelectric fibers. However, most of these fiber-based piezoelectric sensors are thin films, which might had poor air permeability, or do not adapt to complex body movements. In this study, a piezoelectric sensing fabric was proposed based on core-spun Cu/P(VDF-TrFE) nanofibrous yarns. These yarns were fabricated by P(VDF-TrFE) as a piezoelectric material and Cu wire as an inner electrode layer through a one-step conjugate electrospinning process. The Cu/P(VDF-TrFE) fabrics showed good flexibility, breathability, mechanical stability, and sensing capability after continuous running for 60 min or after washing. A 4 cm × 4 cm fabric could generate a current of 38 nA and voltage of 2.7 V under 15 N pressure. Once the fabric was fixed onto the clothes, human motion could be monitored by collecting its generated current, and the signal could be wirelessly transmitted onto a smartphone. Therefore, this study may provide a simple and promising approach to design a smart textile for human motion monitoring.

Static Force Measurement Using Piezoelectric Sensors

Abstract: In force measurement applications, a piezoelectric force sensor is one of the most popular sensors due to its advantages of low cost, linear response, and high sensitivity. Piezoelectric sensors effectively convert dynamic forces to electrical signals by the direct piezoelectric effect, but their use has been limited in measuring static forces due to the easily neutralized surface charge. To overcome this shortcoming, several static (either pure static or quasistatic) force sensing techniques using piezoelectric materials have been developed utilizing several unique parameters rather than just the surface charge produced by an applied force. The parameters for static force measurement include the resonance frequency, electrical impedance, decay time constant, and capacitance. In this review, we discuss the detailed mechanism of these piezoelectric-type, static force sensing methods that use more than the direct piezoelectric effect. We also highlight the challenges and potentials of each method for static force sensing applications.

Self-sensing hybrid composite laminate by piezoelectric nanofibers interleaving

Abstract: One of the most critical aspects of composite materials is their vulnerability to impact loadings In recent years, Structural Health Monitoring (SHM) systems have been developed to continuously watch over on the event of an impact and so monitor the health status of the structure However, this technique needs the integration of sensors in the composite laminate, like Fiber Bragg Grating or piezoelectric ceramic transducers, which often can dramatically reduce the inherent strength of the hosting material The aim of this work is the integration of the composite laminate with a nanostructured piezoelectric sensor, based on PVDF-TrFE nanofibers and aluminum sheets as electrodes Structurally, the resulting composite is a hybrid laminate known as Glass Laminate Aluminum Reinforced Epoxy (GLARE), consisting of aluminum sheets alternatively bonded to glass-epoxy prepreg layers, functionalized with PVDF-TrFE interleaved nanofibrous mats Hence, this nanostructured hybrid laminate becomes itself a piezoelectric sensor, capable to detect impacts on its whole surface Non-destructive impact tests were performed using an instrumented drop-weight tower to investigate the real-time electrical response of the self-sensing laminate A lumped electric model was applied to study and optimize the circuit electrical parameters Then, the self-sensing laminate performance were evaluated in terms of linearity and spatial uniformity

Design and Finite Element Simulation of Metal-Core Piezoelectric Fiber/Epoxy Matrix Composites for Virus Detection.

Abstract: Undoubtedly, the coronavirus disease 2019 (COVID-19) has received the greatest concern with a global impact, and this situation will continue for a long period of time. Looking back in history, airborne transimission diseases have caused huge casualties several times. COVID-19 as a typical airborne disease caught our attention and reminded us of the importance of preventing such diseases. Therefore, this study focuses on finding a new way to guard against the spread of these diseases such as COVID-19. This paper studies the dynamic electromechanical response of metal-core piezoelectric fiber/epoxy matrix composites, designed as mass load sensors for virus detection, by numerical modelling. The dynamic electromechanical response is simulated by applying an alternating current (AC) electric field to make the composite vibrate. Furthermore, both concentrated and distributed loads are considered to assess the sensitivity of the biosensor during modelling of the combination of both biomarker and viruses. The design parameters of this sensor, such as the resonant frequency, the position and size of the biomarker, will be studied and optimized as the key values to determine the sensitivity of detection. The novelty of this work is to propose functional composites that can detect the viruses from changes of the output voltage instead of the resonant frequency change using piezoelectric sensor and piezoelectric actuator. The contribution of this detection method will significantly shorten the detection time as it avoids fast Fourier transform (FFT) or discrete Fourier transform (DFT). The outcome of this research offers a reliable numerical model to optimize the design of the proposed biosensor for virus detection, which will contribute to the production of high-performance piezoelectric biosensors in the future.

Active vibration control of a piezoelectric functionally graded carbon nanotube-reinforced spherical shell panel

Abstract: A finite-element model is presented based on the four-variable shear deformation refined theory for active vibration control of a functionally graded carbon nanotube-reinforced composite spherical panel with integrated piezoelectric layers, acting as an actuator and a sensor. The linear distribution of the electric potential across the thickness of the piezoelectric layer and different distribution types of carbon nanotubes through the thickness of the layers are considered. The weak form of the governing equation is derived using Hamilton's principle, and a four-node nonconforming rectangular element with eight mechanical and two electrical degrees of freedom per node is introduced for discretising the domain. A constant velocity feedback approach is utilised for the active control of the panel by closed-loop control with a piezoelectric sensor and actuator. The convergence and accuracy of the model are validated by comparing numerical results with data available in literature. Some new parametric studies are also discussed in detail.

Mechanism for using piezoelectric sensor to monitor strength gain process of cementitious materials with the temperature effect

Abstract: Recently, the piezoelectric based sensor coupled with electromechanical impedance (EMI) technique is gaining attention on monitoring the mechanical properties changes in cementitious materials. How...

All-Fiber Laser-Self-Mixing Sensor for Acoustic Emission Measurement

Abstract: Self-mixing interferometry (SMI) is a promising non-destructive sensing technology with advantages of simplicity in system structure, low cost in implementation, ease in optical alignment, and high resolution in measurement. It consists of a laser diode, a photodiode packaged at the rear of the laser diode, a lens, and a target to be measured. Typically, SMI-based sensing is to measure the phase change in an SMI signal with a fringe pattern as sinusoidal or saw-tooth like. The phase is called optical phase in external cavity that is linked to the quantity to be measured, e.g., displacement, velocity, and vibration. Each SMI fringe maps to a half-laser-wavelength displacement of the target. With increasing feedback level in an SMI system, some fringes may lost or even totally disappear. In this case, the laser output from an SMI system can trace the optical phase to achieve a linear sensing relationship. In this article, we design an all-fiber SMI linear sensor for real-time and fast tracking acoustic emission (AE) signals. Firstly, a system design in terms of selection of operating parameters is presented. Then, a proof of concept experimental system was built for detecting AE signals. The results show that the proposed SMI sensor has comparable AE detection capability to piezoelectric sensor, providing a compact and cost-effective optical AE sensing solution without need of extra signal processing, which can be considered as a viable alternative to the well-established piezoelectric AE sensor.

Structural Failure Detection Using Wireless Transmission Rate From Piezoelectric Energy Harvesters

Abstract: This article presents a new self-powered wireless failure detection method that uses different signal transmission rates from piezoelectric energy harvesters. Reliable signal transmission from a wireless sensor network has been challenging due to the power supply issue, often covered by batteries that need regular replacement. Piezoelectric energy harvesting is an excellent option to power the sensors in a vibrational environment, but the power level is limited by input vibrational energy. In this article, we introduce a new failure detection strategy that uses multifunctional piezoelectric material for vibration sensing and energy harvesting. That is, when the vibration is stronger and the material strain is higher, piezoelectric material produces higher voltage, and power. Different power level from multiple piezoelectric sensors is used for sensing structural failure. We design a simple power management circuit that saves power proportional to the piezoelectric voltage so that the piezoelectric patch with higher strain can transmit more frequent wireless signals (higher transmission rate). To store the piezoelectric power, the circuit is composed of a full-bridge rectifier, a single pole double throw switch, a comparator with hysteresis, and a wireless transmitter (Zigbee). The failure detection performance is investigated in a case study that monitors screw joint failure in a vibrating plate. Reliability-based design optimization is conducted to determine the piezoelectric sensor network in terms of the number and sizes of multiple piezoelectric (PZT) patches. The test results show that the proposed system successfully powers the wireless transmitter using the ultra-low scale of power from the PZT sensors (microwatt) and detect the different combination of screw joint failure in the vibrating plate.

Dielectric, ferroelectric, and piezoelectric properties of Gd-modified CaBi 2 Nb 2 O 9 high Curie temperature ceramics

Abstract: This paper reports the enhanced piezoelectric properties of gadolinium-modified Ca1−xGdxBi2Nb2O9 (CBN-100xGd, where x = 0–0.07) high Curie temperature polycrystalline ferroelectric ceramics. The crystal structure, microstructural morphology, and electrical properties of Gd-modified CBN ceramics are investigated in detail. The results reveal that the Gd-modified CBN ceramics have a pure two-layer Aurivillius-type structure, and exhibit plate-like grains. The resultant Gd-modified CBN ceramics exhibit better piezoelectric and electromechanical properties by comparison with unmodified CBN. The composition of CBN-3Gd exhibits the optimized piezoelectric performance with a high piezoelectric constant d33 value of 13 pC/N and a high Curie temperature Tc of 947 °C. The dc electrical resistivity is significantly enhanced, and that of the CBN-3Gd is 2.45 × 107 Ω cm at 500 °C and 1.53 × 106 Ω cm at 600 °C, which is larger by two orders of magnitude compared with that of unmodified CBN ceramics at the same temperature. Such good electrical properties suggest that the Gd-modified CBN ceramics are promising materials for high-temperature piezoelectric sensor applications.

Piezoelectric enhancement of an electrospun AlN-doped P(VDF-TrFE) nanofiber membrane

Abstract: Piezoelectric materials are well known for their applications in self-powered sensing and mechanical energy harvesting. With the development of the Internet of things and wearable electronics, piezoelectric polymers are attracting more attention due to their advantages of flexibility, ease of fabrication and biocompatibility. However, low piezoelectric properties weaken their electrical response to external excitation. Doping is one convenient measure to improve their piezoelectric properties. Here we reported AlN-doping-induced piezoelectric enhancement in electrospun poly(vinylidene fluoride-trifluoroethylene) nanofiber membranes. Piezoelectric property measurements under both perpendicular and transverse modes verified that a limited AlN doping of 0.1 wt% could effectively enhance the piezoelectric responses of P(VDF-TrFE)/AlN nanocomposite membranes. Based on such optimized nanofiber membranes, flexible and wearable piezoelectric sensors were further designed to detect finger movement, wrist artery pulse and multi-touch recognition. Our work provided a facile measure to fabricate high-electroactivity nanocomposite membranes for sensing applications in wearable and flexible electronics.

Nonlinear vibration of conical shell with a piezoelectric sensor patch and a piezoelectric actuator patch

Abstract: In this study, nonlinear vibration of a conical shell with a piezoelectric sensor patch and a piezoelectric actuator patch is evaluated. The strain displacement relation is considered to be nonline...

Accurate recognition of object contour based on flexible piezoelectric and piezoresistive dual mode strain sensors

Abstract: The application of flexible wearable sensors in the grasping process of robot hand can recognize the contour, soft and hard, material, surface temperature and other information of the grasping object, which can effectively improve the intelligent level of the robot. In this work, a method of object contour recognition is proposed by combining the flexible PVDF polymer piezoelectric sensor and high conductivity hydrogel piezoresistive sensor aiming at the problem of profile recognition for objects of the same or similar material. The response of flexible piezoresistive sensor to the static strain is used to sense the angular displacement of robot fingers, and then the shape and size of the object is recognized indirectly. At the same time, the flexible piezoelectric sensor is used as the fingertip tactile sensor to reflect the surface morphology of the object through the dynamic strain information when touching the object. In the whole process of grasping the object, the dual-mode strain information is fully used to realize the recognition of the shape, size and surface morphology of the object. Combining these information, the accurate recognition of the object contour can be further realized. In the experiments, six objects with different shape and four objects with different surface morphology are recognized to verify the feasibility of piezoresistive sensors and piezoelectric sensors respectively. In a comprehensive experiment, eight objects made of the same rubber material with different shape, size and surface morphology are recognized, and the average recognition rate is about 84%, which shows good classification advantages for the objects with similar shape, size and material.

A Flexible Piezoelectric Energy Harvester-Based Single-Layer WS2 Nanometer 2D Material for Self-Powered Sensors

Abstract: A piezoelectric sensor is a typical self-powered sensor. With the advantages of a high sensitivity, high frequency band, high signal-to-noise ratio, simple structure, light weight, and reliable operation, it has gradually been applied to the field of smart wearable devices. Here, we first report a flexible piezoelectric sensor (FPS) based on tungsten disulfide (WS2) monolayers that generate electricity when subjected to human movement. The generator maximum voltage was 2.26 V, and the produced energy was 55.45 μJ of the electrical charge on the capacitor (capacity: 220 μF) when applying periodic pressing by 13 kg. The generator demonstrated here can meet the requirements of human motion energy because it generates an average voltage of 7.74 V (a knee), 8.7 V (a sole), and 4.58 V (an elbow) when used on a running human (weight: 75 kg). Output voltages embody distinct patterns for different human parts, the movement-recognition capability of the cellphone application. This generator is quite promising for smart sensors in human–machine interaction detecting personal movement.