Self-powered Pressure Sensor Research Articles

Performance Analysis of Embedded Mechanoluminescence-Perovskite Self-Powered Pressure Sensor for Structural Health Monitoring

Recent developments in sensing technologies have triggered a lot of research interest in exploring novel self-powered, inexpensive, compact and flexible pressure sensors with the potential for structural health monitoring (SHM) applications. Herein, we assessed the performance of an embedded mechanoluminescent (ML) and perovskite pressure sensor that integrates the physical principles of mechanoluminescence and perovskite materials. For a continuous in-situ SHM, it is crucial to evaluate the capabilities of the sensing device when embedded into a composite structure. An experimental study of how the sensor is affected by the embedment process into a glass fiber-reinforced composite has been conducted. A series of devices with and without ML were embedded within a composite laminate, and the signal responses were collected under different conditions. We also demonstrated a successful encapsulation process in order for the device to withstand the composite manufacturing conditions. The results show that the sensor exhibits distinct signals when subjected to different load conditions and can be used for the in-situ SHM of advanced composite structures.

Boosting piezoelectric response of PVDF-TrFE via MXene for self-powered linear pressure sensor

Piezoelectric film pressure sensors are forthcoming choices for self-powered flexible and portable electronics because of their unique advantages in instant response and linear pressure-electrical signal relationship. However, it is commonly of challenge to achieve high output voltage response to pressure in piezoelectric polymer films. Here, we report a piezoelectric film pressure sensor fabricated by electrospun polyvinylidene-fluoride-trifluoroethylene (PVDF-TrFE)/MXene nanofiber mats. As a new two-dimensional nanomaterial, MXene has not only a large amount of surface functional groups to enable interaction with the dipoles of PVDF-TrFE molecular chains, but also high electrical conductivity to potentially increase the polarization of PVDF-TrFE during electrospinning. As such, by comparison with the control pressure sensor consisting of neat PVDF-TrFE film, the composite film sensor shows significantly improved output voltage, and the improvements are closely dependent on MXene content. For instance, the composite film with 2.0 wt% MXene can achieve an instantaneous output power density of ~3.64 mW/m2 under the pressure of 20 N with the frequency of 1 Hz. Such piezoelectric PVDF-TrFE/MXene films are capable of sensing body motion for healthcare. Furthermore, the hydrophilicity of MXene allows the film pressure sensor to monitor humidity change, thus the composite film sensor demonstrates potential application in multifunctional electronic skins.

Light-Driven Piezo- and Triboelectricity in Organic-Inorganic Metal Trihalide Perovskite toward Mechanical Energy Harvesting and Self-powered Sensor Application.

A single-structured multifunctional device capable of energy harvesting and sensing multiple physical signals has significant potential for a wide range of applications in the Internet of Things (IoT). In this study, the fabricated single-structured device based on methylammonium lead iodide-polyvinylidene fluoride (MAPbI3-PVDF) composite can harvest mechanical energy and simultaneously operate as a self-powered light and pressure sensor because of the combined photoelectric and piezoelectric/triboelectric properties of the MAPbI3-PVDF composite. Light-dependent dielectric and piezoelectric properties of composite films are thoroughly investigated. Light and contact electrification effect on device performance in both piezoelectric and triboelectric modes is also systematically investigated. When the device is operated as a harvester in both piezoelectric and triboelectric modes, remarkable light-driven outputs were observed under illumination; the outputs decreased in the piezoelectric mode, while they increased in the triboelectric mode. Such light-controlled properties enabled the device to operate as a self-powered photodetector with outstanding responsivity (∼129.2 V/mW), rapid response time (∼50 ms), and satisfactory detectivity (∼1.4 × 1010 Jones) in the piezoelectric mode. The same device could also operate as a pressure sensor that exhibited excellent pressure sensitivity values of 0.107 and 0.194 V/kPa in the piezoelectric and triboelectric modes, respectively. In addition, the device exhibits a fast response time with long-term on-off switching properties, excellent mechanical durability, and long-term stability.

Self-powered flexible pressure sensors based on nanopatterned polymer films

Purpose The pressure sensors can convert external pressure or mechanical deformation into electrical power and signal, which cannot only detect pressure or strain changes but also harvest energy as a self-powered sensor. This study aims to develop a self-powered flexible pressure sensor based on regular nanopatterned polymer films. Design/methodology/approach In this paper, the self-powered flexible pressure sensor is mainly composed of two nanopatterned polymer films and one conductive electrode layer between them, which is a sandwich structure. The regular nanostructures increase the film roughness and contact area to enhance the friction effect. To enhance the performance of the pressure sensor, different nanostructures on soft polymer sensitive layers are fabricated using UV nanoimprint lithography to generate more triboelectric charges. Findings Finally, the self-powered flexible pressure sensor is prepared, which consists of sub-200 nm resolution regular nanostructures on the surface of the elastic layer and an indium tin oxide electrode thin film. By converting the friction mechanical energy into electrical power, a maximum power of 423.8 mW/m2 and the sensitivity of 0.8 V/kPa at a frequency of 5 Hz are obtained, which proves the excellent sensing performance of the sensor. Originality/value The acquired electrical power and pressure signal by the sensor would be processed in the signal process circuit, which is capable of immediately and sustainably driving the highly integrated self-powered sensor system. Results of the experiments show that this new pressure sensor is a potential method for personal pressure monitoring, featured as being wearable, cost-effective, non-invasive and user-friendly.

Flexible piezoelectric nanogenerators based on a CdS nanowall for self-powered sensors

Wurtzite-structured CdS material is widely used in information sensing and energy harvesting. Based on the piezoelectric property of CdS, we present a flexible piezoelectric nanogenerator (PENG) with three-dimensional-structured CdS nanowall arrays. Under index finger oscillations at a slow rate, the maximal open-circuit voltage and short-circuit current are 1.2 V and 6 nA respectively. Meanwhile, the working mechanism of this PENG was successfully studied with piezoelectric potential distribution and energy band theory respectively. All of the results show that an increase in the bending degree and bending frequency will affect the output of the PENG, suggesting that it can be used as a flexible sensor. In addition, the fabricated PENG can be used as a self-powered pressure sensor relying on the linear relationship between the output voltage and the vertical pressure. This work may provide a new approach to fabricating piezoelectric nanogenerators based on three-dimensional materials as an energy harvester, which may also facilitate the development of flexible and wearable electric sensing technology.

Resistive random access memory based on gallium oxide thin films for self-powered pressure sensor systems

The resistive switching (RS) behavior of a gallium oxide (Ga2O3) thin film for use in resistive random access memory (RRAM) was investigated. Ta/Ga2O3/Pt memory devices exhibited favorable RS behavior, such as a small distribution of switching parameters and switching cycles of more than 3 × 106. X-ray photoelectron spectroscopy and the current transport mechanism indicated that that the RS behavior was attributed to the local variation on the Schottky barrier near the Pt electrode interface due to oxygen vacancies. A hybrid system for self-powered data storage and deletion was built by combining the RRAM device with a commercial Pb(Zr1-xTix)O3 piezoelectric ceramic as a pressure sensor/power generator. The excellent anti-interference and reuse performance of the system indicated promising potential for the application of this memory device.

Wearable self-powered pressure sensor by integration of piezo-transmittance microporous elastomer with organic solar cell

There is a great demand for the development of self-powered physical sensors for wearable applications in recent years. However, it is still challenging to achieve self-powered sensors with a high stability, accuracy, and linearity. Here, a novel wearable self-powered pressure sensor based on the integration of a piezo-transmittance microporous elastomer (PTME) and a thin-film organic solar cell (OSC) is proposed. In contrast to the sensors based on other mechanisms such as piezoelectricity or triboelectricity, the proposed self-powered pressure sensor is cable of measuring static pressure continuously and stably, and utilizes the ambient light as the power source regardless of its intensity. The PTME shows the light transmittance changes by a gradual closure of micropores with compression in response to the applied pressure. This unique optical characteristics of the PTME enables the OSC to generate varying electrical current in response to the pressure. The proposed self-powered pressure sensor shows a high-performance with a sensitivity of 0.101/kPa, a linearity of R2 = 0.995, and fast and reversible response to the pressure up to ~100 kPa. As practical applications of the proposed sensor, a detection of flexion/extension of a human finger for the manipulation of a prosthetic robot finger and a wind detection for the continuous monitoring of the wind speed and direction have been demonstrated.

Matching the Directions of Electric Fields from Triboelectric and Ferroelectric Charges in Nanogenerator Devices for Boosted Performance.

SummaryEmbedding additional ferroelectric dipoles in contacting polymer layers is known to enhance the performance of triboelectricnanogenerator (TENG) devices. However, the influence of dipoles formed between the triboelectric surface charges on two contacting ferroelectric films has been ignored in all relevant studies. We demonstrate that proper attention to the alignment of the distinct dipoles present between two contacting surfaces and in composite polymer/BaTiO3 ferroelectric films can lead to up to four times higher energy and power density output compared with cases when dipole arrangement is mismatched. For example, TENG device based on PVAc/BaTiO3 shows energy density increase from 32.4 μJ m−2 to 132.9 μJ m−2 when comparing devices with matched and mismatched dipoles. The presented strategy and understanding of resulting stronger electrostatic induction in the contacting layers enable the development of TENG devices with greatly enhanced properties.

Three-Dimensional Multistack-Printed, Self-Powered Flexible Pressure Sensor Arrays: Piezoelectric Composites with Chemically Anchored Heterogeneous Interfaces.

Recently, the development of pressure sensor devices composed of mechanically flexible materials has gained a tremendous attention for emerging wearable electronics applications. Compared with various sensing materials, piezoelectric composite materials provide a characteristic advantage of enabling energy unit-free integration of sensor compartments. In this study, we develop a new chemical method of synthesizing highly functioning piezoelectric composite materials with electrostatically reinforced heterogeneous interfaces to improve the voltage output signal in all-printed sensor arrays. The surfaces of piezoelectric oxide nanoparticles are decorated subsequently with a cationic polyelectrolyte, polyethyleneimine, and a tri-block copolymer, styrene–ethylene/butylene–styrene grafted with maleic anhydride. To elucidate the factors determining the performance of pressure sensor devices, both the electrical properties and piezoelectric characteristics are investigated comprehensively for various compositional composite materials prepared from chemical and physical rubbers. The resulting device exhibits a sensitivity of 0.28 V·kPa–1 with a linear increment of output voltage in a pressure range up to 30 kPa. It is also demonstrated that the all-printed sensor array is fabricated successfully by a multistack-printing process of conductive, insulating, and piezoelectric composite materials in an additive manufacturing fashion.

Hierarchical elastomer tuned self-powered pressure sensor for wearable multifunctional cardiovascular electronics

Wearable pressure sensors, as essential components of flexible wearable electronics, may play important roles in early diagnosis and mortality prevention for cardiovascular healthcare. However, traditional self-powered pressure sensors can hardly obtain both high sensitivity and wide pressure range, which makes perceiving both cardiac and vascular signals in a wearable self-powered way challenging as these physiological signals not only have imperceptible changes but also span a broad pressure range. Here, we develop a flexible hierarchical elastomer tuned self-powered pressure sensor, which achieves both high-sensitivity and wide pressure range, showing a high sensitivity of 7.989 V kPa−1 and wide pressure range of 0.1–60 kPa simultaneously. Fast response (40 ms) and high signal noise ratio (38 db) with good stability are also achieved. We demonstrate that the self-powered pressure sensor can not only sensitively monitor pulse, artery and heart condition but also monitor the wide range blood pressure, which satisfies the diverse needs of wearable cardiovascular healthcare. As most of the pressure related to human interface is less than 50 kPa, we envision the sensor holds great potential in wearable electronics, mobile healthcare and human-machine interaction.

Inner egg shell membrane based bio-compatible capacitive and piezoelectric function dominant self-powered pressure sensor array for smart electronic applications.

Flexible pressure sensors play a key role as an interface between the mechanical movements and electrical stimuli in smart skins, soft robotics, and health monitoring systems. However, conventional pressure sensors face several challenges in terms of their bio-compatibility, higher cost, and complicated fabrication process. This paper demonstrates a novel 5 × 5 bio-compatible capacitive and self-powered piezoelectric pressure sensor array using natural inner egg shell membrane (IESM). The proposed sensor array is supported by two different sensing modes, which are capacitive and piezoelectric function dominant self-powered mode. The capacitive mode can detect both static and dynamic pressures and the piezoelectric function dominant self-powered mode can be adopted to detect the dynamic pressure applied on the device. The fabricated device with a sensing area of 4 mm2 offered the sensitivity of 37.54 ± 1.488 MPa−1 in the capacitive pressure sensing range from 0 to 0.05 MPa. The device showed the response (Tres) and recovery time (Trec) of 60 ms and 45 ms, respectively. The device achieves the sensitivity of 16.93 V MPa−1 from the sensing range of 0 to 0.098 MPa in the self-powered pressure sensing. These results depict that the proposed pressure sensor array will ensure a promising role in green, wearable, and soft electronic applications.

State-of-the-art and recent developments in micro/nanoscale pressure sensors for smart wearable devices and health monitoring systems

Small-sized, low-cost, and high-sensitivity sensors are required for pressure-sensing applications because of their critical role in consumer electronics, automotive applications, and industrial environments. Thus, micro/nanoscale pressure sensors based on micro/nanofabrication and micro/nanoelectromechanical system technologies have emerged as a promising class of pressure sensors on account of their remarkable miniaturization and performance. These sensors have recently been developed to feature multifunctionality and applicability to novel scenarios, such as smart wearable devices and health monitoring systems. In this review, we summarize the major sensing principles used in micro/nanoscale pressure sensors and discuss recent progress in the development of four major categories of these sensors, namely, novel material-based, flexible, implantable, and self-powered pressure sensors.

Hierarchically Rough Structured and Self-Powered Pressure Sensor Textile for Motion Sensing and Pulse Monitoring.

Nowadays, real-time human motion sensing and pulse monitoring can provide significant basis for health assessment and medical diagnosis. Nevertheless, it is still a big challenge to design a lightweight, flexible, and energy-sustainable pressure sensor with high sensitivity and breathability. Here, we fabricated a triboelectric all-fiber structured pressure sensor via a facile electrospinning technique. The constructed sensor textile holds a composite structure made up of a polyvinylidene fluoride/Ag nanowire nanofibrous membrane (NFM), an ethyl cellulose NFM, and two layers of conductive fabrics. This wearable device with high shape adaptability exhibited excellent sensing capability because of the introduced hierarchically rough structure on the nanofibers. The sensitivity can reach up to 1.67 and 0.20 V·kPa-1 in the pressure range of 0-3 and 3-32 kPa, respectively. The fabricated sensor textile also showed a superior mechanical stability even after continuous operation of 7200 working cycles. This sensor textile was easily conformable on different desired body parts for dynamic motion sensing and real-time pulse monitoring. It can work in a self-powered manner to detect and quantify various human motions associated with joints, such as elbows, knees, and ankles. Additionally, it can be placed on the carotid artery to capture the pulse signals, serving as a reliable way to reflect the state of health. This work has great possibilities to promote the rapid advancement and broad applications of multifunctional pressure sensors and next-generation wearable electronics.

Monocharged Electret Nanogenerators: A Monocharged Electret Nanogenerator‐Based Self‐Powered Device for Pressure and Tactile Sensor Applications (Adv. Funct. Mater. 41/2019)

With the rapid development of the internet of things, sensors play an increasingly critical role in the measurement of force, temperature, and light. In article number 1807618, Kailiang Ren, Zhong Lin Wang, and co-workers propose a self-powered pressure sensor based on an electret nanogenerator. This device holds great promise for use in future tactile sensors and artificial skin applications.

Understanding the dynamic response in ferroelectret nanogenerators to enable self-powered tactile systems and human-controlled micro-robots

Self-powered pressure sensors are critical devices in IoT sensing networks. Continuous efforts have been made in the community to improve the device performances by optimizing the materials selection and structural configurations. Therefore, a design platform for understanding the device-machine interface is imperative. This work presents a comprehensive study that uses the fundamental working principles of dipole moments in ferroelectret polymers to describe the energy conversion mechanism. The study addresses discrepancies in voltage measurements caused by instruments with different internal resistances and sampling rates. A lumped parameter model is also proposed and validated to explain the impedance mismatch at the device-machine interface. Applications including control of MEMS microactuator through static response and dynamic pressure sensor array for impact distribution sensing have also been demonstrated.

A laser ablated graphene-based flexible self-powered pressure sensor for human gestures and finger pulse monitoring

Flexible triboelectric nanogenerators (TENGs)-based pressure sensors are very essential for the wide-range applications, comprising wearable healthcare systems, intuitive human-device interfaces, electronic-skin (e-skin), and artificial intelligence. Most of conventional fabrication methods used to produce high-performance TENGs involve plasma treatment, photolithography, printing, and electro-deposition. However, these fabrication techniques are expensive, multi-step, time-consuming and not suitable for mass production, which are the main barriers for efficient and cost-effective commercialization of TENGs. Here, we established a highly reliable scheme for the fabrication of a novel eco-friendly, low cost, and TENG-based pressure sensor (TEPS) designed for usage in self-powered-human gesture detection (SP-HGD) likewise wearable healthcare applications. The sensors with microstructured electrodes performed well with high sensitivity (7.697 kPa−1), a lower limit of detection (∼ 1 Pa), faster response time ( 4,000 compression-releasing cycles. The proposed method is suitable for the adaptable fabrication of TEPS at an extremely low cost with possible applications in self-powered systems, especially e-skin and healthcare applications.

Tactile UV- and Solar-Light Multi-Sensing Rechargeable Batteries with Smart Self-Conditioned Charge and Discharge.

A tactile, UV- and solar-light multi-sensing smart rechargeable Zn-air battery (SRZAB) with excellent cell performance, self-conditioned charge/discharge, and reliable environmental responsivity is made by using multi-scale conjugated block-copolymer-carbon nanotube-polyurethane foam assemblies as both a self-standing air electrode and a sensing unit. Multiscale engineering fully exploits the multi-synergy among components to endow the newly designed metal-free multi-sensing air electrode (MSAE) with bifunctional oxygen reduction and evolution activities, pressure sensitivity, and photothermal and photoelectric conversion functions in a single electrode, enabling effective regulation of interface properties, electronic/ionic transport, or redox reactions in SRZAB upon various stimulations and establishing multiple working principles. MSAE-driven SRZAB can be used as compressible power sources, self-powered pressure and optical sensors and light-to-electrochemical energy systems.

A Self-Powered Wearable Pressure Sensor and Pyroelectric Breathing Sensor Based on GO Interfaced PVDF Nanofibers

This paper reports a self-powered, flexible, piezo- and pyro-electric hybrid nanogenerator (NG) device that can be fixed on different locations of human skin for detecting static and dynamic pressu...

Expandable microsphere-based triboelectric nanogenerators as ultrasensitive pressure sensors for respiratory and pulse monitoring

Physiological monitoring sensors have attracted increasing research interest due to their broad application potential in daily activities, sports performance and health status monitoring for next generation athletic/clinical technologies. Having high sensitivity and low power consumption are essential to realize these applications in advanced portable/remote forms. In this work, triboelectric nanogenerators (TENGs), which are based on expandable microspheres in a polydimethylsiloxane (PDMS) mixture, were constructed as self-powered pressure sensors with ultrahigh sensitivity for biological signal monitoring through a low-cost and simple processing technique. Different sensitivities can be obtained by adjusting the weight percentage of microspheres in the PDMS, and the output voltage of the sensor was analyzed by a theoretical model, which was consistent with the simulation results. The maximum sensitivity of the sensor can reach 150 mV/Pa so respiratory and pulse monitoring can be implemented by attaching the ultrasensitive pressure sensor to the chest and wrist of a human body, respectively.

Pressure Sensitivity Enhancement of Porous Carbon Electrode and Its Application in Self-Powered Mechanical Sensors.

Microsystems with limited power supplies, such as electronic skin and smart fuzes, have a strong demand for self-powered pressure and impact sensors. In recent years, new self-powered mechanical sensors based on the piezoresistive characteristics of porous electrodes have been rapidly developed, and have unique advantages compared to conventional piezoelectric sensors. In this paper, in order to optimize the mechanical sensitivity of porous electrodes, a material preparation process that can enhance the piezoresistive characteristics is proposed. A flexible porous electrode with superior piezoresistive characteristics and elasticity was prepared by modifying the microstructure of the porous electrode material and adding an elastic rubber component. Furthermore, based on the porous electrode, a self-powered pressure sensor and an impact sensor were fabricated. Through experimental results, the response signals of the sensors present a voltage peak under such mechanical effects and the sensitive signal has less clutter, making it easy to identify the features of the mechanical effects.