Self-powered Pressure Sensor Research Articles

Ultrahigh sensitive and rapid-response self-powered flexible pressure sensor based on sandwiched piezoelectric composites

Flexible sensors and actuators are the basis for realizing the Internet of Everything. This study identifies specific interfacial polarization and filler dispersion challenges in flexible sensors. A novel sandwich-structured flexible sensor with polydimethylsiloxane (PDMS)-filled Nb2CTx as the interlayer and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]-filled barium titanate (BTO) as the upper and lower layers was designed and fabricated. The thickness of the interlayer was optimized to be 6.2 μm, resulting in an ultrahigh sensitivity of 16.05 V/N and ultrashort response time of 626 μs. The interlayer achieved an oriented arrangement of the dipoles in the upper and lower piezoelectric films through interfacial polarization, enhancing the piezoelectric output and sensitivity. The proposed mechanism was confirmed by the dielectric properties, local piezoelectric response, cross-sectional potential simulation, and interfacial electrical calculations. Additionally, the sensor effectively distinguishes various body movements, facial micro-expressions, and throat vibrations during vocalization, and can be applied to ultrahigh-sensitive self-powered flexible piezoelectric pressure sensors.

Ultrafast, self-powered monolithic pressure sensing technology induced by piezo-pyrophototronics

Pressure sensing is a pivotal aspect of modern technology that has been extensively explored, but still presents significant challenges. This work introduces an innovative ultrafast self-powered pressure sensing technology by harnessing the lateral photovoltaic effect (LPE) in a CIGS heterojunction via piezo-pyrophototronics. By utilizing non-uniform irradiation, a surface gradient of charge carriers is induced, resulting in the generation of a lateral photovoltage (LPV) that contributes to the excellent self-powered characteristic of the sensor. This gradient is then coupled with external pressure through the piezo-phototronic effect, enabling the sensing capability of the device. The enhancement of LPV, which is dependent on the irradiation position, power and wavelength, exhibits an extremely linear relationship with the applied external pressure ranging from 0 to 2.0 MPa. Besides, the pyroelectric field generated by transient temperature variations introduces an additional modulation to the pressure sensing effect, leading to an impressive pressure sensitivity of 64.25 mV/MPa, and a rapid response speed of 7.8/8.9 μs. This work highlights the benefits of the lateral photovoltaic effect, piezo-phototronic effect, and pyroelectric modulation in developing highly sensitive and ultrafast self-powered pressure sensors.

A self-powered flexible tactile sensor utilizing chemical battery reactions to detect static and dynamic stimuli

Flexible and wearable tactile sensors have become increasingly important in various fields, including healthcare monitoring and human-computer interaction. However, traditional resistive or capacitive sensors require an external power supply to continuously consume energy, while piezoelectric and triboelectric sensors respond only to dynamic mechanical stimuli. The development of tactile sensors that do not require an external power source and are capable of monitoring dynamic/static mechanical stimuli could complement the shortcomings of existing sensing devices. In this paper, we propose a simple, convenient, and environmentally friendly paper-based sandwich solid Zn-MnO2 battery, which can be used as a self-powered flexible tactile sensor through simple structural design. As a battery, it exhibited an open circuit voltage of 1.29 V, the highest short circuit current density of 2.8 mA/cm2, and a capacity of 2.2 mAh/cm2 at a current density of 0.1 mA/cm2, which is sufficient to power small electrical appliances. As a self-powered pressure sensor, it exhibits an average sensitivity of 1.27 μA/kPa in the 0–25 kPa and 0.14 μA/kPa within the 25–500 kPa pressure range, a response time of 42 ms and a recovery time of 41 ms, a minimum pressure resolution of tens of Pascals, and long-period repeatability and stability. This work will significantly contribute to the further advancement of intelligent, self-powered tactile sensors for a wide range of applications in fields such as human healthcare and human-machine interfaces for detecting static and dynamic stimuli.

Multimodal sensing algorithm using thermoelectric dynamics for self-powered skin-like sensory devices

In the rapidly evolving field of electronic skins (e-skins), the development of self-powered sensors has emerged as a promising solution to providing continuous and reliable power sources for embedded sensors. This study introduces a novel approach that incorporates spike-shaped nickel (Ni) microparticles into a styrene-ethylene-butylene-styrene (SEBS) matrix, resulting in a thermoelectric material that functions as both an energy harvester and a pressure sensor, and a multimodal sensing algorithm designed to mitigate pressure sensing errors arising from temperature fluctuations in the thermoelectric self-powered pressure sensor. The Ni-SEBS composite, with a sensing mechanism that identifies changes in the Ni particle percolation state induced by compressive strain, exhibited a high sensitivity of 0.6234 kPa−1. Based on this composite, a dual-channel self-powered sensor was fabricated using the proposed algorithm and attached to the skin; the sensor successfully detected various forms of external pressure applied to the skin without errors due to temperature changes.

Triboelectric nanogenerator based on multi-component crosslinked network hydrogel for intelligent human motion sensing

With the continuous development of intelligent wearable devices, new requirements are put forward for the collection of human motion information. In this paper, a self-powered motion sensor with high precision, high stability and high output power was prepared by utilizing the flexibility and stretchability of the conductive hydrogel and combining with the nanogenerator. Even at a contact frequency of 3.0 Hz, the sensor can produce an open circuit voltage of 225 V and a power density of 187 mW m−2. It can not only be used as a power source to drive electronic devices, but also to achieve accurate acquisition of human movement steps and walking speed. When applying different forces, the sensor shows a more obvious difference, and its theoretical resolution can reach 0.1 N. Because the hinge hydrogel has good flexibility, resilience and stability, it can still maintain its original shape after 4000 times of pressure testing, and can be directly attached to the human skin surface, providing a new idea for the field of self-powered pressure sensors.

High density Ti3C2TX-graphene quantum dot-Ru monolithic film electrode with rich anisotropic microstructures for high-performance supercapacitor and piezoresistive pressure sensor

Ti3C2TX become a promising electrode and pressure sensing material because of high conductivity. However, poor anisotropy limit its practical applications in high-performance pressure sensor. This study reports one solution for protonated arginine and serine-functionalized graphene quantum dot (RS-GQD+)-regulated synthesis of Ti3C2TX-Ru monolithic film. Dropped RS-GQD + aqueous solution to Ti3C2TX aqueous solution to initiate the self-assembly of Ti3C2TX sheets. Followed by reaction with RuCl3 to produce Ru nanocrystals and subsequent vacuum filtration. Adjusting amounts of RS-GQD + results in formation of monolithic Ti3C2TX-Ru film with ultrahigh density of 3.52 g cm−3 and rich anisotropic microstructures. The structure achieves to excellent supercapacitor and pressure sensing behavior. The soft symmetrical supercapacitor with Ti3C2TX-Ru film electrodes without current collector, conductive agent and binder exhibits ultrahigh specific capacitance of 779.3 F g−1 at 1 A g−1 (1828.7 F cm−3) and energy density of 43.8 W h kg−1 at 225 W kg−1. The Ti3C2TX-Ru film pressure sensor offers high-resolution distinguish subtle and complex pressure changes with superhigh sensitivity and precision. Its piezoresistive current linearly increases with increasing pressure between 0.02 and 30 kPa with detection limit of 0.0067 kPa. The self-powered pressure sensor shows broad application prospect in monitoring human movement, writing and facial expression.

Self-Powered Dual-Mode Pressure Sensor Based on Porous Triboelectric Nanogenerator for Use in Smart Home System

With the rapid evolution of the Internet of Things (IoT), smart home systems have greatly improved people’s lifestyles and quality of life. However, smart home systems based on a single sensor cannot efficiently control multiple terminals, which limits product penetration into lower-end markets. Here, we have developed a dual-mode smart home system based on a porous triboelectric nanogenerator (TENG), which effectively compensates for the shortcomings of smart home systems being unable to control multiple appliances through a single switch. Benefitting from the remarkable electronegativity of MXene and the ameliorative specific surface area of the friction layer, the output characteristics of the porous TENG are greatly improved. Under the identical external stimulus, the open-circuit voltage (VOC) and short-circuit current (ISC) of the porous TENG were 3.03 and 3.04 times higher than those of the TENG with a pure PVDF membrane used as the friction layer. Thanks to the excellent output performance and good linear relationship between pressure and voltage, the developed dual-mode smart home system could efficiently control multiple terminals through a single sensor. This work not only provides theoretical support for developing high-performance TENGs but also paves the way to designing multifunctional smart home systems.

A skin-wearable and self-powered laminated pressure sensor based on triboelectric nanogenerator for monitoring human motion

Flexible and skin-wearable triboelectric nanogenerators (TENGs) have emerged as promising candidates for self-powered tactile and pressure sensors and mechanical energy harvesters due to their compatible design and ability to operate at low frequencies. Most research has focused on improving tribo-negative materials for flexible TENGs, given the limited options for tribo-positive materials. Achieving biocompatibility while maintaining the sensitivity and capability of energy harvesting is another critical issue for wearable sensors. Here, we report a TENG-based biocompatible and self-powered pressure sensor by simple fabrication of layer-by-layer deposition methods. The Laminated Flexible-TENG comprises polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) films embedded within a flexible and biocompatible polydimethylsiloxane (PDMS) matrix. A nanostructured PDMS surface obtained by oxygen plasma facilitated the sputter deposition of a layered indium tin oxide copper electrode and a tribo-positive PMMA thin layer on top. The addition of the indium tin oxide layer to copper significantly improved the quality and performance of the indium tin oxide-copper electrode. Self-powered Laminated Flexible-TENGs demonstrated impressive pressure-sensing capabilities, featuring dual sensitivity of 7.287 V/kPa for low pressure and 0.663 V/kPa for higher pressure. Moreover, the PDMS-encapsulated TENG sensor effectively traced the physiological motions, such as wrist and finger bending, and efficiently harnessed the waste energy from everyday physical activities, such as walking and jogging. The maximum peak-to-peak voltages of 18.3 and 57.4 V were recorded during these motions. Encapsulated TENGs have broad potential in wearable technology, including healthcare, human-machine interfaces, and energizing microelectronics.

Kirigami-inspired self-powered pressure sensor based on shape fixation treatment in IPMC material

Rapid advances in sensing technologies have brought about the fast development of wearable electronics for biomedical applications. Since its conception, over the years, the ionic polymer metal composite (IPMC) is a new man-made material that has demonstrated its great potential for wearable devices due to self-powered sensing capabilities. Here, for the first time, a novel Kirigami technique with unique cut patterns has been employed for designing a stretchable IPMC sensor with enhanced performance. As Nafion itself exhibits the characteristic of shape memory polymer, the Kirigami structure that is built using the IPMC can be buckled up by loading and heating the IPMC above the deformation temperature, T def. To further enhance the memory effect, the Kirigami structure has further been locked by immersing it in potassium hydroxide for the formation of deprotonated Nafion. The voltage output of the proposed IPMC with Kirigami shows a superior performance with 3 times improvement over the conventionally planar electrodes. Dynamic tests with a range of displacements have been performed to validate the sensor design and the robustness of the Kirigami structure. This novel Kirigami-based IPMC sensor has been successfully demonstrated for braille sensing by designing 7 independent electrodes.

Hierarchical Wrinkles with Piezopotential Enhanced Surface Tribopolarity for High-Performance Self-Powered Pressure Sensor.

Achieving both high sensitivity and wide detecting range is significant for the applications of triboelectric nanogenerator-based self-powered pressure sensors (TPSs). However, most of the previous designs with high sensitivity usually struggle in a narrow pressure detection range (<30 kPa) while expanding the detection range normally sacrifices the sensitivity. To overcome this well-known obstacle, herein, piezopotential enhanced triboelectric effect realized by a rationally designed PDMS/ZnO NWs hierarchical wrinkle structure was exploited to develop a TPS (PETPS) with both high sensitivity and wide detecting range. In this PETPS design, the piezopotential derived from the deformation of ZnO NWs enhances its tribo-charge transferring ability; meanwhile, the hierarchical structure helps to establish a dynamically self-adjustable contact area. Benefiting from these advantages, the PETPS simultaneously achieves high sensitivity (0.26 nC cm-2 kPa-1 from 1 to 25 kPa, and 0.02 nC cm-2 kPa-1 from 25 to 476 kPa), fast response (46 ms), wide sensing range (1 to 476 kPa), and good stability (over 4000 cycles). In addition, the output charge density that is independent of the speed rate of driven force was adopted as the sensing signal of PETPS to replace the commonly used peak voltage/current values, enabling it more adaptive to accurately detect pressure variation in real applications.

Lead-free hybrid halide perovskite-based piezo/triboelectric self-powered wearable dual-functional sensors

A self-powered dual-functional humidity and pressure sensor based on piezo/triboelectric nanogeneration using tin-based halide perovskites embedded with copper halides is reported here. The device can be used as a colorimetric humidity sensor along with the piezo/triboelectric nanogeneration.

A facilely fabricated electrochemical self-powered pressure sensor for multifunctional applications

A facilely fabricated, low-cost and multifunctional electrochemical self-powered pressure sensor is achieved using a simple method and cheap raw materials.

Dome-Conformal Electrode Strategy for Enhancing the Sensitivity of BaTiO3-Doped Flexible Self-powered Triboelectric Pressure Sensor.

A microstructured surface has been applied in self-powered triboelectric pressure sensors to increase the charge-carrying sites and enhance the output performance. However, the microstructure increases the distance between the electrode and the triboelectric layer, and its influence on the output performance is unknown. Herein, we proposed a dome-conformal electrode strategy for a self-powered triboelectric nanogenerator (TENG) pressure sensor. With a simple reverse-dome adsorption process, an ultrathin triboelectric layer and Ag electrode can be made conformal to the dome PDMS structure. The TENG sensor is constructed with paper as a positive triboelectric layer. Compared with the device based on nonconformal structure, the conformal design strategy endows the device with a faster charge transfer and enhanced output voltage. By doping with BaTiO3, the outermost triboelectric layer can be easily modified to improve its ability of sustaining charge, and an ultrathin PDMS layer is coated on the triboelectric layer to expand the triboelectric polarity difference between two triboelectric layers so as to enhance the output voltage. The synergistic effects enable the optimized TENG sensor with a sensitivity of 0.75 V/kPa in the low-pressure region (0-26 kPa) and 0.19 V/kPa in the high-pressure range (26-120 kPa). Its application in human motion detection, grabbing water beakers, and noncontact distance testing has been demonstrated. This work provides a route such as a conformal structure design strategy to enhance the output performance of a microstructure-based TENG sensor.

A flexible triboelectric nanogenerator based on wave structure PDMS for joint monitoring in basketball training

Recently, intelligent sports wearable devices have attracted widespread attention. Hence, we designed a wave-structure triboelectric nanogenerator (W-TENG) for joint monitoring in basketball training. The self-powered pressure sensor is mainly composed of polydimethylsiloxane (PDMS) film and aluminum foil with corrugation characteristics. The wave structure of the PDMS film is designed based on sine waves, and results have indicated that the higher the amplitude, the higher the sensing performance of the W-TENG. Moreover, the W-TENG has two sensing monitoring areas. For low pressure areas, the sensing sensitivity of the W-TENG is 3.564 V kPa−1 and 37.644 nA kPa−1. For high pressure areas, the sensing sensitivity of the W-TENG is 0.024 V kPa−1 and 19.92 nA kPa−1. This W-TENG pressure sensor can be installed at the joints of basketball players’ bodies to monitor the degree of joint bending. This design can facilitate the development of wearable basketball training devices.

Self-powered flexible battery pressure sensor based on gelatin

The application of pressure sensors with excellent performance in medicine, flexible electronic skin, artificial intelligence, etc. has received much attention. However, most of the current pressure sensors have either the need for an external power supply or the difficulty of accurately measuring the static continuous signal, which greatly limit the development of sensor technology. We report a gelatin-based battery type pressure sensor in which a gelatin composite hydrogel membrane is introduced as the sensing layer in a zinc ion battery, and the zinc battery itself is designed as a pressure sensor. An isolation layer is also added to the solid zinc ion battery to realize the function of converting mechanical pressure signals to electrical signals more accurately. The gelatin battery pressure sensor designed in this paper has the advantages of being self-powered, high sensitivity (37.9 mV/kPa), wide pressure detection range (up to 524 kPa), good stability, short response/recovery time, and high biological applicability. In addition, the battery-type pressure sensor has the ability to detect static signals and maintain good performance under 10,000 s of external mechanical pressure. The design of this battery-based pressure sensor provides a new strategy for the development of self-powered pressure sensors and flexible electronic skin devices.

Synergistic promotion between tolerant polymer electrode and super-conductive polyelectrolyte enables anti-damage transient wearable electronics

Manufacturing highly durable and transient materials is urgently needed to achieve optimal performances in wearable electronics. Here, a comprehensive methodology to enhance the durability and transience of wearable electronics by utilizing polypyrrole/vermiculite/polysaccharide (PPy/VMT/AF) electrodes and acid-assisted polyacrylamide (HPAM) electrolytes. The mechanical/thermal/electrochemical properties of integrated electrodes are boosting by introducing negatively charged vermiculite in conductive polymer-polysaccharide, which can be completely degrade after 90 days. Pre-gel drying shrinkage and rehydration were utilized to prepare polyacrylamide hydrogel with frost resistance and ultrahigh conductivity (increased 32.2 times as compared to traditional polyacrylamide). The synergism between PPy/VMT/AF and HPAM enables flexible solid-state supercapacitors with exceptional electrochemical stability even under serious damage such as puncturing, burning and freeze. In addition, the fabricated self-powered pressure sensor realizes ML-assisted human motion recognition with an accuracy of 95.7 %. This work opens up a new perspective on future directions for multifunctional platforms for wearable electronic devices.

Skin-interfaced self-powered pressure and strain sensors based on fish gelatin-based hydrogel for wireless wound strain and human motion detection

Biomass-based hydrogels, due to their excellent biocompatibility, can behave as wearable monitoring platforms for healthcare applications and triboelectric sensing devices. However, low tissue adhesiveness, poor stretchability, and bacterial susceptibility cause them to fail to adapt to specific joints with complex movements. Herein, we report a novel biomass-based hydrogel by integrating fish gelatin into polymer networks with in-situ formation of silver nanoparticles (denoted as FG-Ag hydrogel), which achieves great stretchability (2600%), excellent sensitivity (gauge factor = 4), and strong self-adhesion simultaneously. The FG-Ag hydrogel also features a robust antibacterial activity for Escherichia coli and Staphylococcus aureus. Benefitting from these advantages, we have developed a FG-Ag hydrogel-based wearable strain sensor for diverse human-motion detections such as elbow, knee, finger, and wrist bending. Moreover, we have demonstrated an FG-Ag hydrogel-based prototype with an integrated wireless system for real-time strain monitoring on the wound sites. The FG-Ag hydrogel could significantly reduce bacterial infection in vivo and effectively promote wound healing. Additionally, the self-powered pressure sensor and the biomechanical energy harvester also have been demonstrated by the FG-Ag hydrogel based triboelectric nanogenerator (TENG). Accordingly, such FG assistance of hydrogel-based skin-interfaced electronics could provide adequately delicate biomechanical information related to the general health, which furnishes essential technical support for cost-effective, all-green, and highly precise personalized health assessment.

Harnessing highly efficient triboelectric sensors and machine learning for self-powered intelligent security applications

In the contemporary epoch, distinguished by a transition from the internet-of-things (IoT) to the artificial intelligence of things (AIoT), individual electronic appliances necessitate inherent power-generation, independence from internet connectivity, and an imbued degree of intellect. Devices governed by pressure or strain sensors particularly demand such attributes. Responding to this technological imperative, our study endeavored to conceive an intelligent door security apparatus grounded on the universally adopted numerical input system. Despite the commercialization of identification systems such as fingerprint, iris, or facial recognition, these mechanisms suffer from susceptibility to a variety of functional aberrations. Consequently, our investigation concentrated on a security system predicated on numerical input. This necessitated the formulation of a swift, self-powered pressure sensor characterized by sensitivity to minute pressure changes. As such, we engineered a triboelectric pressure sensor incorporating a composite of Ti3C2-based MXene and polydimethylsiloxane (PDMS) as the electronegative stratum, and Nylon functioning as the electropositive layer. Addressing the sensor's intrinsic deficiency in sensitivity to pressure, we augmented the MXene-PDMS composite's surface with an out-of-plane wavy structure, and utilized a Nylon stratum composed of nanofibers, thereby amplifying the contact area under pressurized conditions. This meticulously developed sensor displayed a sensitivity metric of 0.604 kPa−1 at 15 kPa, and notably, the swiftest response times recorded amongst triboelectric pressure sensors to date. Post attachment of the sensor to a numeric keypad (ranging from 0 to 9), we meticulously measured the signal alterations contingent on each key press, resulting in a comprehensive dataset. Employing a multitude of machine learning algorithms, we realized an exemplary degree of precision in both training and testing phases. The pragmatic implications of this work are noteworthy. Not only does our technology facilitate the unlocking of a door by entering the correct numerical code, but it is capable of recognizing distinct triboelectric signal patterns, corresponding to the specific manner of key entry by an authorized user, offering an additional dimension of security.

Electrospinning of Highly Bi-Oriented Flexible Piezoelectric Nanofibers for Anisotropic-Responsive Intelligent Sensing.

Flexible piezoelectric energy harvesters (PEHs) have gained substantial attention owing to their wearability, breathability, and sustainable self-powered supply. However, existing film PEHs cannot identify forces in different bending directions, limiting their applications in wearable electronics and artificial intelligence. This study constructs a fabric PEH for the first time by introducing piezoelectric anisotropic BaTi2 O5 nanorods (BT2-nr) into piezoelectric polyvinylidene fluoride (PVDF) nanofibers with a bi-oriented architecture, in which BT2-nr uniformly aligns in the PVDF nanofiber during electrospinning. The dual-orientation feature endows the flexible PEH with anisotropy, which can sensitively identify the forces at different bending directions (e.g., bent vertically, parallelly, or twisted by 45° along the fiber orientations). Simultaneously, the composite PVDF/BT2 PEH containing 15wt.% BT2-nr delivers an optimal piezoelectric output of 31.2V with a high sensitivity of 5.22V N-1 . The developed anisotropic PEH can be used as a self-powered pressure sensor for multimodal intelligent biomonitoring of human movement. This study provides a feasible strategy for fabricating self-powered flexible PEHs with high electromechanical conversion efficiency and multifunctionality for wearable piezoelectric pressure sensors.

Triboelectric active pressure sensor with ultrabroad linearity range by femtosecond laser shaping based on electrons dynamics control

Pressure sensor plays an extremely important role for the pulse monitoring, which has greatly demands of sensitivity and ultrabroad linearity sensing range. Here, we propose a active triboelectric pressure sensor with ultrabroad linearity range by femtosecond laser shaping gradient height microstructures for triboelectric layers. We fabricate microcolumn arrays with gradient height on polydimethylsiloxane (PDMS) surfaces using femtosecond laser spatial-temporal shaping technology to shape Gaussian beam into double-pulse Bessel beams, and supplementing it with wet etching and imprinting technology. Based on these fabricated PDMS layers, the effects of the microcolumns with different gradients on the linearity range of the sensor are systematically characterized. When the height difference of the microcolumns is 2 µm, the sensor can maintain a high linearity (R2 ≈ 0.99996) with a sensitivity of 0.304 V·kPa-1 even when the detection pressure range reaches 0–330 kPa, which increase the linearity range of the pressure measurements by 66 times than that with uniform height microcolumns. As practical applications of the proposed sensor, it is shown to sense weak airflow, generate high-stability Morse code signals, and enable the detection of pathological heart rates. These results highlight the potential applications of self-powered triboelectric pressure sensors for health monitoring and human machine interaction.