External Power Research Articles

Joint kinetic demand for performance in high jump

ABSTRACT High jump is a power-demanding motor task. Jumpers extend the take-off leg joints with maximum effort, but kinetic requirements (i.e. torque/power) for each joint are unclear. Here we show the inter-joint differences in the kinetic exertion related to the flight height in high jump trials by 16 male high jumpers (personal best record: 1.90–2.35 m). For the knee joint, both maximum net power and maximum norm of torque were significantly and positively correlated with flight height, with a stronger correlation for maximum net power (r = 0.70) than for maximum norm of torque (r = 0.52). For the hip joint, maximum norm of torque was significantly correlated with flight height (r = 0.62), but maximum net power (r = 0.36) was not. Both torque and power exhibited the proximal-to-distal sequence (from hip to ankle). The norm of ground reaction force peaked almost simultaneously with the hip torque while external net power peaked with knee power. We suggest that the required musculoskeletal function of each joint differs even in the same task. We suggest that it may be effective to adapt the different training programme between joints to improve performance. Jumpers should prioritise torque exertion for the hip and power exertion for the knee.

Computational Investigation of the Operating Mechanism of the Ranque–Hilsch Vortex Tube

Abstract The Ranque–Hilsch vortex tube is a device that splits an incoming flow into two outgoing streams, but with the peculiar property that one stream exits at a lower total temperature than the incoming flow and the other at a higher total temperature. This temperature separation is accomplished without any moving parts, electronics or external power supplied to the device. Despite the passage of nearly a century since discovery of the effect, there remains a dearth of understanding regarding the mechanism responsible for the phenomenon. In fact, the literature contains competing theories with little evidence providing support. A promising technique to discern the responsible mechanisms for the energy transfer from the ultimately cold stream to the ultimately hot stream is to define a stream tube in a computational simulation of the flow that propagates upstream from the exits such that the stream tube interface separates the hot flow from the cold flow. In this article, we apply this method to a three-dimensional, full-volume analysis of the flow within a vortex tube using a computational simulation that was thoroughly validated against experiments on a physical replica of the computational geometry. In this novel study, the integral form of the energy equation was used to quantify all forms of the energy transfer within the vortex tube. The results demonstrate that the phenomenon of temperature separation is attributable primarily to viscous work in the radial direction due to the circumferential flow, with a lesser contribution from heat transfer in the radial direction.

Improved hole injection for AlGaN-based DUV LEDs with graded-composition multiple quantum barrier insertion layers

The primary impediments to achieving high external quantum efficiency (EQE) and light output power (LOP) in AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) are inadequate hole injection efficiency and pronounced electron leakage. The significant polarization-induced positive charges, originating from the discontinuity in the Al composition between the last quantum barrier (LQB) and electron-blocking layer (EBL), attract electrons, consume holes, and reflect holes back into the p-type region, leading to severe electron leakage and low hole injection efficiency. In this paper, we introduce a graded-composition multiple quantum barrier (GQB) structure at the LQB/EBL interface. We adjust the Al composition in the insertion layer to alter the electrical polarity of the polarization-induced sheet charges, thereby modifying the electric field distribution in the EBL, LQB, and inserted GQB structure. Consequently, holes acquire boosted energy during their migration towards the active region. In addition, we enhance the hole injection and electron confinement ability via reducing the effective valence band barrier height and increasing the effective conduction band barrier height, thus diminishing the possibility of electron leakage from the active region into the p-type region. Therefore, the GQB structure proposed in this study provides a promising approach to improving the optical and electrical performance of DUV LEDs.

Self-Powered Potentiometric Sensor with Relational Operation Function to Capture Concentration Excursions.

Self-powered potentiometric sensors spontaneously respond to activity changes of target species without the need for an external power source. Here, a self-powered potentiometric sensing approach is described that may store concentration perturbations that occur before the sensor readout through a combination of capacitors and diodes. Two channels, termed "more than" and "less than" operators, are utilized as memory modules in the sensor circuit to record positive and negative concentration excursions, respectively. Each channel is constructed with a capacitor-diode pair in which each diode is connected to a capacitor in the opposite direction to prevent unwanted capacitor discharge. With this design, only potential variations that agree with the polarity of the diode may pass and be stored in the capacitor. A limitation of the principle is that the conductivity of the diode is very small if the voltage across it diminishes over time as it approaches the equilibrium value. To address this, the forward voltage is increased by about 1 V by switching from an initial Ag/AgCl reference electrode (RE) to a Zn/Zn2+ element. The device may be used to monitor whether a concentration excursion has occurred in the time leading up to the signal readout in a semiquantitative manner. The approach also differentiates pH excursions of different durations (20, 40, 60 min). As an example, four different pH excursions of 20 min duration were successfully distinguished in river water samples with amplitudes of 1 to 4 pH units relative to the case without pH perturbation.

Ultra‐Sensitive, Self‐powered, CMOS‐Compatible Near‐Infrared Photodetectors for Wide‐Ranging Applications

AbstractSelf‐powered near‐infrared (NIR) photodetectors are essential for surveillance systems, sensing in IoT electronics, facial recognition, health monitoring, optical communication networks, night vision, and biomedical imaging. However, silicon commercial detectors need external power to operate and cooling to suppress large dark currents. This work demonstrates a new class of CMOS‐compatible self‐powered NIR photodetector based on ferroelectric 5‐nm thick ZrO2 films which do not require cooling and therefore have two key advantages over Si, and at the same time have comparable performance metrics. At room‐temperature, under 940 nm wavelength illumination (1.4 mW cm−2 power density, 10 Hz repetition rate), and without any power applied, fast rise and fall times of ≈2 and 4 µs, respectively, are achieved in Al/Si/SiOx/ZrO2/ITO devices, along with responsivity, detectivity and sensitivity values of up to ≈3.4 A W−1, 1.2 × 1010 Jones and 4.2 × 103, respectively, far exceeding all other emerging self‐powered systems. Furthermore, dual‐band NIR detection is shown for different NIR wavelengths, proof‐of‐concept feasibility being demonstrated for the smart identification of NIR targets. Therefore, it is demonstrated, for the first time, that coupling together the pyroelectric effect, the photovoltaic effect, and the ferroelectric effect is a novel method to significantly enhance the performance of CMOS‐compatible ZrO2‐based self‐powered photodetectors in the NIR region.

Real-Time Wireless Detection of Heavy Metal Ions Using a Self-Powered Triboelectric Nanosensor Integrated with an Autonomous Thermoelectric Generator-Powered Robotic System.

The integration of the Internet of Things (IoT) with advanced sensing technologies is transforming environmental monitoring and public health protection. In this study, a fully self-powered and automated chemical sensing system is developed and integrated with a robotic hand for "touch and sense" detection of toxic heavy metal ions (Pb2⁺, Cr⁶⁺, As3⁺) in aquatic environments. The system combines a self-powered solid-liquid triboelectric nanosensor (SL-TENS) with a thermoelectric generator (TEG), which harnesses ambient heat to power the robotic hand, eliminating the need for external power sources. The robotic hand is controlled wirelessly via an exo-hand, minimizing the risk of exposure during remote monitoring. The sensing component uses copper oxide nanowires (CuO NWs) coated with ion-selective membranes (ISMs) to enhance triboelectric output and enable highly selective ion detection. The system demonstrates effective real-time, on-site detection in lake water and data transmitted wirelessly to the user. This innovative approach provides a highly safe and efficient method for detecting hazardous pollutants in difficult-to-access areas, offering significant potential for wireless and real-time environmental monitoring and hazard prevention, thus contributing to the safeguarding of human health. This study presents a novel advancement in the field of IoT-enabled environmental monitoring systems.

A passive, flexible dual-function sensor for simultaneous pressure and sliding direction detection

Flexible pressure and omnidirectional slide sensors show significant potential in wearable devices and robotics. However, the integration of various sensor types to achieve multi-functionality introduces challenges. Complex structures and processing difficulties limit their miniaturization and flexibility, while dependence on external power sources further constrains their practical use. Here, we report a novel strategy that utilizes a piezoelectric-conductive nanoresistance network with edge electrodes to develop an advanced pressure sensor. This sensor is capable of simultaneously detecting pressure and sliding direction through multiple-channel pulses. We demonstrate its functionality using a polyacrylonitrile/polypyrrole nanofiber membrane (PAN/PPY NFM) configured with either two or three electrodes. By exploiting the signal transmission characteristics of the nanoresistance network, the sensor simultaneously responds to both force and sliding direction through amplitude-frequency analysis of the output signals from multiple channels. Additionally, the sensor operates without an external power supply. This streamlined approach simplifies sensor design and processing, providing a promising solution for advanced touch sensing applications.

Tin can telephone-inspired self-powered mechanical wave communication integrated with self-charge excitation triboelectric nanogenerator

As an alternative to electromagnetic wave communication, mechanical waves (MW) retain their advantage in several aspects, including cost-effectiveness, simplicity, interference resistance, and short-distance transmission. Here, a string-vibrated self-powered mechanical wave communication system (SSMWC) is proposed. Inspired by tin can telephone, modulated voltage signals are converted into MW by a vibrator and then transmitted along a string to the receiver. The receiver integrates a string-vibrated triboelectric nanogenerator (SV-TENG) and a self-charge excitation triboelectric nanogenerator (SCE-TENG). The SV-TENG can detect MW and convert them into electrical signals without external power sources, while the SCE-TENG is integrated to improve the sensitivity of the receiver. After charges pumping of SCE-TENG, the average output of SV-TENG can increase by 88 times within the frequency range of 0-1000Hz, indicating the successful application of self-charge excitation in triboelectric sensing for the first time. Furthermore, a demonstration of information coding and real-time decoding proves the potential application of SSMWC as an alternative in specific environments. This work shows the breakthrough of the bottlenecks faced by triboelectric sensors that the essential preparatory contact electrification before packaging, which indeed affect sensitivity and durability. Therefore, this scheme can be widely applied for output enhancement, especially for triboelectric sensors with lower output.

Wireless power supply near-infrared light drug-loaded microneedle system for the treatment of linear skin wounds

The healing of linear skin wounds is a complex biological process, and traditional treatment methods have certain limitations. This study proposes a wireless power supply near-infrared light drug-loaded microneedle system (NIR-LED-NG-R1-MN), which utilizes microneedles (MNs) to achieve targeted delivery of the active component of traditional Chinese medicine, Notoginsenoside R1 (NG-R1), and combines the biological regulatory effect of near-infrared light (NIR) to achieve efficient synergistic treatment for linear skin wounds. Experimental results show that the device can significantly promote the wound closure rate and reduce the levels of inflammatory factors and the risk of scar formation. By comparing the wound repair conditions of different treatment groups, it was found that the group treated with the NIR-LED-NG-R1-MN patch for NG-R1 and NIR synergistic treatment (MN@NG-R1@LED group) showed superior wound repair effects compared to other groups, thus confirming the synergistic therapeutic advantages of NG-R1 and NIR in skin wound healing. In addition, the application of wireless power supply technology used in this system eliminates the dependence on external power sources, enhancing the convenience of treatment. This study clearly demonstrates that the NIR-LED-NG-R1-MN has the potential to become a new clinical method for the treatment of linear skin wound healing.

A composite structure device: vibration control and energy harvesting of tool system in aviation thin-walled parts milling process

Abstract The intense vibration generated by the high-speed milling cutter in the processing process not only seriously affects the surface roughness but also may damage important components of the machine tool, resulting in significant economic losses. Therefore, a composite structure of piezoelectric energy-collector (PEC) and nonlinear energy sink (NES) is innovatively constructed by combining theoretical research and numerical analysis to achieve more efficient vibration suppression and energy recovery in milling. Using the Hamilton principle, the electromechanical model of the composite structure is developed. Then, based on the Galerkin truncation to discretized displacement functions, we solve the amplitude-frequency response of the tool structure by using the harmonic balance method. The validity analysis of the proposed method can be verified by rigorous comparison with the results of the Runge-Kutta method. A novel NES-PEC composite structure presented in this work shows excellent vibration suppression capability in the milling process. More importantly, the structure also enables self-powered sensing of the tool system, significantly reducing dependence on external power sources. This innovative design substantially improves the stability and reliability of milling processes and opens up new ways to optimize the energy efficiency of tool systems. In summary, this paper’s modeling and solving methods, vibration reduction techniques, and energy harvesting strategies have laid a solid foundation for applying a high-speed milling cutter system. More relevant literature on applying vibration suppression and energy harvesting devices in milling must be reviewed. This paper fills in the research gap and provides a valuable reference for future tool systems design and optimization.

Self-Powered Machine-Learning-Assisted Material Identification Enabled by a Thermogalvanic Dual-Network Hydrogel with a High Thermopower.

Wearable devices equipped with high-performance flexible sensors that can identify diverse physical information free from batteries are playing an indispensable role in various fields. However, previous studies on flexible sensors have primarily focused on their elasticity and temperature-sensing capability, with few reports on material identification. In this paper, a thermogalvanic dual-network hydrogel is fabricated with [Fe(CN)6]3-/4- as a redox couple and lithium magnesium silicate, Gdm+ and lithium bromideas key electrolytes to optimize the interconnected porous structure of the gel, which shows excellent mechanical and thermoelectric properties with a thermopower as high as 4.01mV K-1. A self-powered material identification ring is developed based on the temperature-triggered thermoelectric response of the gel in conjunction with machine learning, which can actively infer materials without an external power connection by analyzing the voltage signals correlated with interfacial heat transfer produced upon contact with different materials. The proposed gel ring has important applications for future areas such as human-computer interaction and haptic-associated artificial intelligence.

Graphene electrochemical biosensors combining effervescent solid-phase extraction (ESPE) for rapid, ultrasensitive, and simultaneous determination of DA, AA, and UA

Simultaneous monitoring of key metabolites like dopamine, ascorbic acid, and uric acid is essential for early disease diagnosis and evaluating treatment. Electrochemical techniques are increasingly used for precise, point-of-care testing (POCT) of these metabolites. Herein, a sample pretreatment method called effervescent solid-phase extraction (ESPE) was proposed for efficient enrichment of trace analytes for electrochemical detection. In an ESPE process, effervescent tablets made of gold nanoparticle-decorated graphene oxide (Au/GO) were first self-dispersed in a test solution to promote the enrichment of analytes on the Au/GO adsorbents, followed by the addition of flocculant effervescent tablets to cause Au/GO sheets to form self-assembled aggregates, which then can be efficiently collected by the foam electrodes. The entire sample pretreatment process operates without external power and takes only 5 min. With the assistance of the ESPE method, our electrochemical sensors achieve an ultralow detection limit for dopamine, ascorbic acid, and uric acid of 80 pM, 1.8 nM, and 460 pM, respectively, which are two to three orders of magnitude lower than the results obtained by the drop casting technique. The enhancement mechanism of our approach is based on increasing the contact probability with analytes through dynamic dispersion of the Au/GO adsorbents, in contrast to the static diffusion mechanism relied on Brownian motion. We also show that combining the ESPE solution kit with a portable micro-electrochemical workstation can attain the same detection level as HPLC in real urine samples. The proposed ESPE approach holds great promise for POCT applications in 2D material-based biosensors.

Model-based design of a mechanically intelligent shape-morphing structure

Soft robotics has significant interest within the industrial applications due to its advantages in flexibility and adaptability. Nevertheless, its potential is challenged by low stiffness and limited deformability, particularly in large-scale application scenarios such as underwater and offshore engineering. The integration of smart materials and morphing structures presents a promising avenue for enhancing the capabilities of soft robotic systems, especially in large deformation and variations in stiffness. In this study, we propose a multiple smart materials based mechanically intelligent structure devised through a model-based design framework. Specifically, the intelligent structure incorporates smart hydrogel and shape memory polymer (SMP). Employing the finite element method (FEM), we simulated the complex interactions among smart material to analyze the performance characteristics of the intelligent structure. The results demonstrate that, utilizing smart hydrogel and shape memory polymer (SMP) can effectively attain large deformation and exhibit variable stiffness due to the shape memory effect. Besides, the shape-morphing structures exhibit customized behaviours including bending, curling, and elongation, all while reducing reliance on external power sources. In conclusion, utilizing multiple smart materials within the model-based design framework offers an efficient approach for developing mechanically intelligent structure capable of complex deformations and variable stiffness, thereby providing support for underwater or offshore engineering applications.

A Plantar Pressure Detection and Gait Analysis System Based on Flexible Triboelectric Pressure Sensor Array and Deep Learning.

Gait detection is essential for the assessment of human health status and early diagnosis of diseases. The current gait analysis systems are bulky, limited in the scope of use, and cause interference with the movement of the measured person. Hence, it is necessary to develop a wearable gait detection system that is soft, breathable, lightweight, and self-powered. Here, a plantar pressure sensor array and gait analysis system based on a flexible triboelectric pressure sensor (FTPS) array is developed. Soft, breathable, and wearable electrospinning nanofiber film with excellent triboelectric properties is used as the plantar pressure sensor, achieving a high sensitivity of 45.1 mVkPa-1 in the range of 40-200 kPa and 19.4 mVkPa-1 in the range of 200-400 kpa. 32 FTPSs are integrated into an intelligent insole, which has the characteristics of soft, easy production, good air permeability, long-time stability, no external power supply, and etc. Based on the long short-term memory artificial neural network deep learning model, the accuracy of gait judgment can reach 94.23%. This work provides a feasible solution for real-time gait detection, which will have potential applications in human health assessment and early diagnosis of disease.

A Star‐Nose‐Inspired Bionic Soft Robot for Nonvisual Spatial Detection and Reconstruction

The star‐nosed mole is recognized as a tactilely sensitive mammal due to its unique nose, which facilitates spatial detection in dark environments through touch using its appendages enveloped in numerous sensory receptors. This article introduces a bionic soft robot inspired by the star‐nosed mole, which combines a pneumatic soft platform with a polydimethylsiloxane–polyethylene terephthalate cylindrical tactile sensor array based on bilayer single‐electrode triboelectric nanogenerators, mimicking the muscle tissue of the mole's nose and the cylindrical appendages surrounded by Eimer's organs. The cylindrical sensor array enables multiangle spatial detection without an external power supply and remains unaffected by external materials. By implementing a constant curvature model for robot motion control, positional information is provided for the contact points between the cylindrical sensor array and the external environment. The robot effectively discriminates the distance and shape of various objects and achieves nonvisual 3D spatial detection and reconstruction in real‐world scenarios. This work presents a novel bionic approach for 3D spatial detection in nonvisual environments.

Templates-Built Structural Designs for Piezoelectrochemical Pressure Sensors.

Self-powered sensors, capable of detecting static and dynamic pressure without an external power source, are pivotal for advancements in human-computer interaction, health monitoring, and artificial intelligence. Current sensing technologies, however, often fall short of meeting the growing needs for precise and timely pressure monitoring. This article introduces a novel self-powered pressure sensor utilizing electrochemical reactions. The sensor's ion conduction path and internal resistance adjust in response to external stress across a broad range. Its three-dimensional structure, crafted by using a simple template on the electrolyte, enables the efficient and cost-effective detection of various mechanical stimuli. This device not only achieves an optimized power density of approximately 2.34 mW cm-2─surpassing most existing technologies─but also features excellent flexibility, quick response, and recovery times (0.15 and 0.19 s respectively); high durability (2000 cycles); and a broad sensing range (0.23-20 kPa). Moreover, it serves as an ionic touchpad, enhancing data collection and recognition, and integrates seamlessly with a mouthpiece for accurate, real-time monitoring of respiratory activities. This innovative sensor offers minimal cost and simple process requirements while providing multifunctional capabilities for energy harvesting and pressure sensing, marking a significant step forward in the design of next-generation sensors.

From Lab to Life: Self-Powered Sweat Sensors and Their Future in Personal Health Monitoring.

The rapid development of wearable sweat sensors has demonstrated their potential for continuous, non-invasive disease diagnosis and health monitoring. Emerging energy harvesters capable of converting various environmental energy sources-biomechanical, thermal, biochemical, and solar-into electrical energy are revolutionizing power solutions for wearable devices. Based on self-powered technology, the integration of the energy harvesters with wearable sweat sensors can drive the device for biosensing, signal processing, and data transmission. As a result, self-powered sweat sensors are able to operate continuously without external power or charging, greatly facilitating the development of wearable electronics and personalized healthcare. This review focuses on the recent advances in self-powered sweat sensors for personalized healthcare, covering sweat sensors, energy harvesters, energy management, and applications. The review begins with the foundations of wearable sweat sensors, providing an overview of their detection methods, materials, and wearable devices. Then, the working mechanism, structure, and a characteristic of different types of energy harvesters are discussed. The features and challenges of different energy harvesters in energy supply and energy management of sweat sensors are emphasized. The review concludes with a look at the future prospects of self-powered sweat sensors, outlining the trajectory of the field and its potential to flourish.

High-efficiency quad-band RF energy harvesting system with improved cross-coupled differential-drive rectifier

Abstract RF energy harvesting technology has garnered significant attention from researchers in recent years. This paper presents a high-efficiency quad-band RF energy harvesting (RFEH) system. It introduces an improved cross-coupled differential-drive rectifier designed for ambient wireless powering, capable of harnessing power from four distinct ambient RF sources: FM-100, DTV-600, GSM-1800, and WiFi-2400 frequency bands. The proposed RFEH system demonstrates notable advancements, achieving a high RF to DC conversion efficiency of over 80 % within an input power range of −5 dB m to +13 dB m, with a 5 kΩ resistance load. This power output is deemed sufficient for energizing low-power micro-devices autonomously, without reliance on external power sources. Notably, the DC output voltage of the proposed RFEH system exhibits a high level of stability against variations in input power, a characteristic not adequately addressed in existing systems.

Hybrid DC circuit breaker power supply system with load constant voltage self‐balancing design

AbstractPower electronic switches (PES) play a crucial role in transferring and clearing fault currents in hybrid DC circuit breakers. The PES encounters switching transients that require a dependable external power source. Usually, a power supply system utilizes an isolation transformer and many magnetic rings. However, the existence of inconsistent parameters might easily cause an imbalance in load power, which could potentially result in power supply failure for the loads. Therefore, to enhance the reliability of power supply, this study proposes a load constant voltage self‐balancing design approach that utilizes feedback circuits to achieve stability and balance in load voltage. At first, two feedback circuits are shown, and the analytical formulas for load active power and load voltage are derived. Moreover, a parameter design methodology is shown for the equivalent circuit of the magnetic rings in the power supply. Additionally, a power supply system is built with 24 V outputs. In conclusion, this study utilizes simulations and tests to assess the effectiveness of the proposed power supply system by analysing its performance during start‐up, load power‐off, and steady‐state operations.

CURRÍCULO E FORMAÇÃO NA EDUCAÇÃO DE JOVENS E ADULTOS: ANÁLISE DOS AVANÇOS, DESAFIOS E PERFIL DE ALUNOS

Analyzing the school curriculum from a post-critical and multi-referential perspective is essential to understand the influence of movements that defend a neutral and impartial curriculum. These moves have significantly shaped official decisions about the curriculum. The aim of this article is to explore how disputes over curriculum definitions go beyond epistemological concerns, encompassing political aspects and power relations, and to assess the implications for Youth and Adult Education (EJA) and teacher training. It is a bibliographic and documentary research. The results suggest that curriculum development is influenced by external power dynamics and political decisions. It is necessary to integrate the continuous training of teachers to better meet the diverse needs of EJA students. Understanding the curriculum as a dynamic and contested space is crucial for effective educational practices. To create an effective and inclusive pedagogical model, it is essential to consider both the theoretical and practical aspects of curriculum development. Reflecting on and learning about continuing professional development for educators from a curriculum that responds to students' experiences and needs is vital to fostering a meaningful learning environment.