External Power Supply Research Articles

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.

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.

Customized Preparation of Heat-Resistant Fully Flexible Sensors Based on Coaxial 3D Printing.

The conventional behavior recognition strategy for wearable sensors used in high-temperature environments typically requires an external power supply, and the manufacturing process is cumbersome. Herein, we present a rational design strategy based on fully flexible printable materials and a customized device-manufacturing process for skin-conformable triboelectric nanogenerator sensors. In detail, using high temperature-resistant ink and 3D printing technology to manufacture a coaxial triboelectric nanogenerator (C-TENG) sensor, the C-TENG exhibits high stretchability (>400%), a wide working range (>250 °C), and high output voltage (>100 V). The C-TENG can be worn on various parts of the human body, providing a robust skin-device interface that recognizes diverse human behaviors. Using machine learning algorithms, behaviors such as walking, running, sitting, squatting, climbing stairs, and falling can be identified, achieving 100% behavior recognition accuracy through the selective input and optimization of an appropriate dataset. This paper provides a research perspective for the customization, extension, and rapid fabrication of heat-resistant, fully flexible TENGs.

Addressing extreme weather events for the renewable power-water-heating sectors in Neom, Saudi Arabia

A renewable energy design optimization model is proposed to plan investments in power, water, and heat technologies. The intermittent nature of renewables requires that these models capture the variability and complementarity of resources at high spatial and temporal resolutions. However, most planning models use time-series reduction methods that, while capturing data variance, often smooth out extreme weather or demand patterns. To account for extreme patterns and design reliable energy systems, we propose a clustering-optimization framework that considers extreme weather days. This framework is applied to design an integrated multi-sector energy system for the Neom region in Saudi Arabia. Our results show that fully renewable systems designed without considering extreme days could not meet demands and instead required external power or water supplies during a post-optimization simulation. Once extreme days were considered in the optimization, system reliability increased at the expense of larger generation and storage capacity investments.

Investigation of Onboard Power Generation Method Using Waste Energy at Altitude Conditions

Abstract Demand for increased onboard power generation on small aircraft is ever growing due to increased electrical power demand. The objective of this study is to investigate onboard power generation using waste energy at various altitude and ambient conditions. Experiments were performed on a 2-liter turbocharged direct-injection intermittent combustion engine fueled with jet fuel (F-24). The turbocharger has an integrated motor-generator system that is designed to generate electricity using the enthalpy in the engine exhaust, or to use as a motor to rotate the turbocharger using the energy stored in onboard energy storage device. An electrically actuated wastegate was used to control useful exhaust flowrate that is used to generate electricity. An external power supply system was used to emulate the energy storage. The engine was installed in the US DEVCOM Army Research Laboratory?s altitude chamber in which absolute outside air pressure was controlled up to 37.6 kPa to simulate the altitude conditions up to 7,620 m (25,000 ft). Three different ambient conditions were selected to represent International Standard Atmosphere (ISA), polar, and tropical conditions. Based on the experimental results, a response surface model was developed to predict the power generation of the motor-generator integrated turbocharger using waste energy as a function of altitude, engine power, and the wastegate position. The result from this study provides an insight into onboard power generation method using waste energy at altitude conditions.

Azobenzene-Functionalized Semicrystalline Liquid Crystal Elastomer Springs for Underwater Soft Robotic Actuators.

As actuated devices become smaller and more complex, there is a need for smart materials and structures that directly function as complete mechanical units without an external power supply. The strategy uses light-powered, twisted, and coiled azobenzene-functionalized semicrystalline liquid crystal elastomer (AC-LCE) springs. This twisting and coiling, which has previously been used for only thermally, electrochemically, or absorption-powered muscles, maximizes uniaxial and radial actuation. The specially designed photochemical muscles can undergo about 60% tensile stroke and provide 15kJ m-3 of work capacity in response to light, thus providing about three times and two times higher performance, respectively, than previous azobenzene actuators. Since this actuation is photochemical, driven by ultraviolet (UV) light and reversed by visible light, isothermal actuation can occur in a range of environmental conditions, including underwater. In addition, photoisomerization of the AC-LCEs enables unique latch-like actuation, eliminating the need for continuous energy application to maintain the stroke. Also, as the light-powered muscles processed to be either homochiral or heterochiral, the direction of actuation can be reversed. The presented approach highlights the novel capabilities of photochemical actuator materials that can be manipulated in untethered, isothermal, and wet environmental conditions, thus suggesting various potential applications, including underwater soft robotics.

High‐performance triboelectric nanogenerator based on a double‐spiral zigzag‐origami structure for continuous sensing and signal transmission in marine environment

AbstractWith the rapid evolution of emerging technologies like artificial intelligence, Internet of Things, big data, robotics, and novel materials, the landscape of global ocean science and technology is undergoing significant transformation. Ocean wave energy stands out as one of the most promising clean and renewable energy sources. Triboelectric nanogenerators (TENGs) represent a cutting‐edge technology for harnessing such random and ultra‐low frequency energy toward blue energy. A high‐performance TENG incorporating a double‐spiral zigzag‐origami structure is engineered to achieve continuous sensing and signal transmission in marine environment. Integrating the double‐spiral origami into the TENG system enables efficient energy harvesting from the ocean waves by converting low‐frequency wave vibrations into high‐frequency motions. Under the water wave triggering of 0.8 Hz, the TENG generates a maximum peak power density of 55.4 W m−3, and a TENG array with six units can generate an output current of 375.2 μA (density of 468.8 mA m−3). This power‐managed TENG array effectively powers a wireless water quality detector and transmits signals without an external power supply. The findings contribute to the development of sustainable and renewable energy technologies for oceanic applications and open new pathways for designing advanced materials and structures in the field of energy harvesting.

High Performance Self‐Powered p+‐GaN/n−‐ZnO/Au UV Heterojunction Phototransistor with 3D Interconnected ZnO Nanowire Network for Solar‐Blind Imaging and Optical Communication

AbstractHeterojunction phototransistor (HPT) is considered the most promising detector technology in weak ultraviolet (UV) signal detection due to its inherent internal gain through transistor action. However, achieving high‐performance self‐powered UV HPTs remains a significant challenge. In this study, a high‐performance self‐powered p+‐GaN/n−‐ZnO/Au UV HPT with ZnO serving as the floating base is cleverly designed. The device features a unique back‐to‐back configuration of the p+‐GaN/n−‐ZnO heterojunction and n−‐ZnO/Au Schottky junction, along with an ultrathin ZnO base layer of a 3D nanowire network structure. This design enables the fabricated p+‐GaN/n−‐ZnO/Au UV HPT to operate in a self‐powered mode with exceptional performance metrics. Under zero bias, the device exhibits outstanding characteristics including ultralow dark current of 1.7 × 10−13 A, remarkable Iphoto/Idark ratio of 106, fast response speed (tr = 150 µs / tf = 250 µs), high responsivity of 9.74 A W−1, and detectivity of 1.58 × 1014 Jones, representing the best result achieved for UV HPTs thus far at zero bias. Moreover, the fabricated UV HPT is successfully demonstrated in solar‐blind imaging and UV communication systems without the need for an external power supply. This work presents effective and practical design strategies for achieving high‐performance self‐powered UV HPTs.

Synergistic Effect of GO and MXene Enables Ultrasensitive, Reversible, and Self-Powered Fire Warning of a GO/MXene/Chitosan Aerogel.

Graphene oxide (GO)-based fire alarm materials have garnered extensive attention because the thermal reduction of GO to reduced GO (RGO) enables rapid fire warning. However, they suffer from poor flame retardancy, irreversible fire warning, and dependence on an external power supply. Herein, a GO/MXene/chitosan aerogel with a low density of 0.018 g cm-3 and good compressibility has been developed. The experimental results demonstrate that (i) MXene effectively reduces the peak and mean heat release rate of GO, while RGO nanosheets compensate for the structural instability of MXene in the flame due to thermal oxidation into TiO2; as such, long-lasting fire warning (>120 s) has been achieved; (ii) the reducibility and conductivity of MXene contribute to the ultrasensitive response of GO, with a fire response time of 1 s; and (iii) notably, the thermoelectric effect of MXene enables the reversible and self-powered fire warning of the GO/MXene/CS aerogel without an external power supply. Compared to pure MXene/CS aerogel, the presence of GO improves the sensitivity and stability of self-powered fire warning, owing to the formation of the highly conductive RGO nanosheets. The results of this work highlight the cooperation between GO and MXene in realizing ultrasensitive, long-lasting, reversible, and self-powered fire warning.

An In2O3/In2S3 photoanode-driven whole-cell biocathode sensor for sensitive detection of nitrate

Whole-cell biocathode sensor is a new form of self-regenerable biosensor and promising for environmental monitoring especially in the scenario with low organic substrate. However, external power supply such as electrochemical workstation is required to drive the biocathode reaction, which greatly limits its application. Herein, a new strategy based on the visible-light-driven whole-cell biocathode was proposed and validated for self-powered sensitive detections. To be specific, 1-OH phenazine was selected as the optimal electron shuttle for a Shewanella oneidensis MR-1 inoculated biocathode, which efficiently mediate the cathodic reaction at an electrode potential below −0.6 V (vs. SCE). Meanwhile, an In2O3/In2S3 photoanode with nanoflower-like structure was fabricated to match the kinetic of the biocathode. The photo-driven biocathode reduction was convinced by comparing with the performance of biocathode in the conventional three-electrode system. With this basis, a self-powered whole-cell biocathode sensor was developed for nitrate detection. An extreme low limit of detection of 0.028 μM (S/N=3) and linear detection range of 0.1–20 μM was achieved. Moreover, this biocathode sensor also exhibited excellent selectivity, reusability, accuracy, stability and was reliable for the detection of complex environmental samples. Therefore, this work developed a new photo-driven whole-cell biocathode sensor with excellent detection capacity of nitrate, which opens up new prospects for the development of high-performance biosensors.

ДЕЯКІ АСПЕКТИ РОЗРАХУНКУ СТРУМІВ КОРОТКОГО ЗАМКНЕННЯ В ДІЛЬНИЧНИХ ПІДЗЕМНИХ МЕРЕЖАХ

The article considers some aspects of calculating short-circuit currents in mine networks of an underground sec-tion; the shortcomings of traditional methods of calculating short-circuit currents are identified. The article shows that for an accurate calculation, it is necessary to know the actual voltage levels at remote points of the underground section. The influence of the complex resistance of the external power supply network and the ac-tual phase parameter was studied. The article states that the voltage is below the nominal value in the electrically remote connection nodes of the substation's mobile transformers to the underground distribution network and usually no regulating taps are used. The article indicates that according to known methods of calculating short-circuit currents, the voltage on the secondary terminals of the substation transformer is assumed to be equal to the nominal voltage of the network, but in remote areas it is significantly lower and, accordingly, the actual short-circuit currents are 10-12% lower than the calculated ones. It was also investigated that with an increase in the share of the active short-circuit power component, short-circuit currents in district networks increase by 4-5%.

Triboelectric Nanogenerator for Self-Powered Gas Sensing.

With the continuous acceleration of industrialization, gas sensors are evolving to become portable, wearable and environmentally friendly. However, traditional gas sensors rely on external power supply, which severely limits their applications in various industries. As an innovative and environmentally adaptable power generation technology, triboelectric nanogenerators (TENGs) can be integrated with gas sensors to leverage the benefits of both technologies for efficient and environmentally friendly self-powered gas sensing. This paper delves into the basic principles and current research frontiers of the TENG-based self-powered gas sensor, focusing particularly on innovative applications in environmental safety monitoring, healthcare, as well as emerging fields such as food safety assurance and smart agriculture. It emphasizes the significant advantages of TENG-based self-powered gas sensor systems in promoting environmental sustainability, achieving efficient sensing at room temperature, and driving technological innovations in wearable devices. It also objectively analyzes the technical challenges, including issues related to performance enhancement, theoretical refinement, and application expansion, and provides targeted strategies and future research directions aimed at paving the way for continuous progress and widespread applications in the field of self-powered gas sensors.

Pressure-induced piezoelectric response for mitigating membrane fouling in surface water treatment: Insights from continuous operation and biofouling characterization

Organic fouling and biofouling represents a critical challenge encountered by the membrane-based water treatment process. Herein, a piezoelectric PVDF membrane (PEM), capable of generating electrical responses to hydraulic pressure stimuli, was synthesized and employed for mitigating the fouling in surface water treatment. The surface-hydrophobilized PEM demonstrated sensitive and enhanced underwater output performance in response to increasing transmembrane pressure (TMP) during constant-flux filtration, with signals reaching up to ∼800 mV at a TMP of ∼80 kPa. This in-situ piezoelectric response significantly reduced TMP growth in both short-term (1 h) and long-term (15 days) filtration trials, demonstrating a strong capability to mitigate membrane fouling. Moreover, continuous piezoelectric stimulation effectively inhibited microbial activity and the accumulation of extracellular polymeric substances (EPS) on PEM surface, surpassing the dominant electrokinetic repulsion mechanisms observed in short-term trials. Microbial community analysis suggests that this evolution is primarily due to the targeted impact of piezoelectric stimulation on microbial metabolic behavior. The piezoelectric-induced electrical microenvironment inhibited the growth of microbes associated with high EPS production while promoting the proliferation of electrically active microbes involved in biopolymer digestion. In addition, the PEM demonstrated enhanced permeate quality throughout the filtration process, with DOC and UV254 removal rates increasing from 11.7 % and 15.6 % initially to 28.6 % and 19.5 % by the 15th day, respectively. Given the performance and self-powered capability of PEM compared to current electrified antifouling methods that require an external power supply, these attributes are anticipated to hold practical significance in developing innovative and energy-efficient strategies for mitigating both organic fouling and biofouling.

Thermogalvanic hydrogel with controllable ion confined transportation and its application for self-powered lactic acid sensor

Low-grade heat energy (below 100 °C) is abundantly available in the natural environment, yet effective utilization remains challenging. Liquid-state thermocells, also known as thermo-electrochemical cells or thermogalvanic cells, have emerged as promising solution for converting low-grade heat into electrical energy due to their high Seebeck coefficients (mV·K–1). However, traditional liquid-state thermocells suffer from the issue of liquid leakage caused by frequent cooling or heating during operation. Here in this work, we propose thermogalvanic hydrogels through introducing redox ions into hydrogel framework. The thermoelectric performance of the proposed hydrogel is highly dependent on the ion concentration, which is attributed to the confined ion transportation in micro/nano channels caused by the salting out effect. After the optimization of thermoelectric parameters, a Π-shaped thermocell composed of three p-n pairs is fabricated to harvest low-grade body heat energy. An open-circuit voltage of 163 mV, a short-current density of 0.7 mA·m–2 and a maximum power density of 26.7 μW·m–2 are achieved at a temperature difference of 30 K. To further demonstrate the practical potential, the thermoelectric generator is integrated with a lactic acid sensor to sensitively detect the lactic acid concentration without any external power supplies.

Self-Powered Traffic Lights Through Wind Energy Harvesting Based on High-Performance Fur-Brush Dish Triboelectric Nanogenerators.

Traffic lights play vital roles in urban traffic management systems, providing clear directional guidance for vehicles and pedestrians while ensuring traffic safety. However, the vast quantity of traffic lights widely distributed in the transportation system aggravates energy consumption. Here, a self-powered traffic light system is proposed through wind energy harvesting based on a high-performance fur-brush dish triboelectric nanogenerator (FD-TENG). The FD-TENG harvests wind energy to power the traffic light system continuously without needing an external power supply. Natural rabbit furs are applied to dish structures, due to their outstanding characteristics of shallow wear, high performance, and resistance to humidity. Also, the grid pattern of the dish structure significantly impacts the TENG outputs. Additionally, the internal electric field and the influences of mechanical and structural parameters on the outputs are analyzed by finite element simulations. After optimization, the FD-TENG can achieve a peak power density of 3.275Wm-3. The portable and miniature features of FD-TENG make it suitable for other natural environment systems such as forests, oceans, and mountains, besides the traffic light systems. This study presents a viable strategy for self-powered traffic lights, establishing a basis for efficient environmental energy harvesting toward big data and Internet of Things applications.

High performance self-powered photodetection and X-ray detection realized by CH3NH3PbI3 single crystal with planar asymmetric Schottky structure

Organic-inorganic hybrid perovskite CH3NH3PbI3 (MAPbI3) single crystals (SCs) have been widely investigated in photodetection and X-ray detection. However, external electric-field-driven ion migration seriously affect the stability of MAPbI3 SCs based optoelectronic devices. Self-powered device can operate without any external power supply, which is suitable for mitigating the ion migration of MAPbI3 SCs. To realize self-powered MAPbI3 SC based photodetector and X-ray detector, an asymmetric Au/CH3NH3PbI3 SC/Au planar Schottky structure is employed in this work. At 0 V, the self-powered photodetector can achieve the responsivity of 11.1 mA/W at the wavelength of 795 nm, and the sensitivity of the self-powered X-ray detector can reach 477.1 μC Gy-1cm-2 with the detection limit of as low as 140.3 nGy s-1. Moreover, the self-powered optoelectronic device exhibits good stability in both photodetection and X-ray detection. Most importantly, high-quality near-infrared bioimaging and X-ray imaging are successfully realized by the above self-powered optoelectronic device.

An Innovative Water Splitting Process for a Sustainable In Situ Hydrogen Generation–Reduction of Nitrobenzenes Catalyzed by a New Bimetallic Nanocatalyst

ABSTRACTIn this research, bimetallic CdNi nanoparticles encapsulated in a magnetic spent coffee ground (Fe3O4@COFF/CdNi) was synthesized as a new nanocatalyst. The structural and chemical characteristics of Fe3O4@COFF/CdNi were comprehensively investigated using various techniques, including FT‐IR, XRD, XPS, TEM, VSM, EDS, TGA, BET, and ICP. Through XRD, XPS analysis, TEM images, and EDS mapping, the presence of CdNi nanoalloys was conclusively established. Fe3O4@COFF/CdNi exhibited remarkable catalytic activity for the hydrogen generation from water using iso‐propanol as a clean sacrificial agent. The high catalytic performance of Fe3O4@COFF/CdNi was attributed to the synergistic cooperative effect of Cd and Ni within CdNi nanoalloys. Interestingly, this process was performed for the in situ generated hydrogen from water to reduce a range of nitrobenzenes simultaneously into the corresponding anilines in high yields (93%–98%). The magnetic and hydrophilic characteristics of Fe3O4@COFF/CdNi facilitated its reusability over five runs. Using water as the most abundant hydrogen source, for the first time for in situ hydrogen generation–reduction of nitrobenzenes without demanding on external light sources or power supplies can be mentioned as a significant milestone of this field of study.

Study on the Improvement of the Degradation Efficiency of Methylene Blue Using Pulsed Direct-Current Self-Power Supply.

Effective treatment of dye wastewater is currently a great concern and a research hotspot. Electrocatalysis has unique advantages in treating toxic and harmful refractory dye wastewater; however, it requires an external power supply, which increases energy consumption and cost. As a new energy collection technology, triboelectric nanogenerators (TENGs) have gained considerable attention. In this study, an origami multilayer spherical friction nanogenerator (Q-TENG) was developed for the removal of methylene blue (MB) from dye wastewater. The current and voltage output performances of Q-TENG were explored, and the removal and degradation mechanisms of MB were discussed. Results indicated that when the water wave acceleration a = 3 m/s2, the open-circuit voltage and short-circuit current reached the maximum values of 179 V and 9.4 μA, respectively. The self-powered catalytic degradation of MB using Q-TENG can produce more •OH and SO4-•, and the free radicals increase with increasing action time of Q-TENG, thus increasing the degradation efficiency of MB. This study provides a new strategy for solving the problem of high energy consumption during electrochemical reactions in wastewater treatment.

Miniature and cost‐effective self‐powered triboelectric sensing system toward rapid detection of puerarin concentration

AbstractThe detection of puerarin concentration is an essential capability to study the functional role of the Pueraria root as a natural medicine and dietary source in the treatment of cardiovascular diseases and liver protection. Current methods to detect and measure puerarin concentration, such as ultraviolet–visible spectrophotometry (UV), are bulky, require an external power supply, and are inconvenient to use. Here, we propose a triboelectric puerarin‐detecting sensor (TPDS) which is based on liquid–solid contact electrification, in which liquid–solid interactions generate rapid electrical signals in only 0.4 ms to enable real‐time detection of puerarin concentration in water droplets. The electrical signal of the TPDS decreases with an increase of puerarin concentration, and the sensitivity of the approach is 520 V·(μg/mL)−1. The TPDS represents a miniature and cost‐effective sensor that is 0.2% of the size and 0.01% of the cost of a UV spectrophotometer. Our theoretical analysis verified that the puerarin concentration in droplets can effectively regulate the electronic structure, where higher concentrations of puerarin lead to a narrower energy bandgap, which allows the TPDS to detect puerarin concentration without the need for an external power supply. The TPDS therefore provides a route for the development of a portable and self‐powered method to measure the concentration of an active ingredient in droplets through the conversion of natural energy.image