External Supply Research Articles

Organic-inorganic hybrid piezotronic bipolar junction transistor for pressure sensing

With the rapid development of the Internet of Things (IoTs), wearable sensors are playing an increasingly important role in daily monitoring of personal health and wellness. The signal-to-noise-ratio has become the most critical performance factor to consider. To enhance it, on the one hand, good sensing materials/devices have been employed; on the other hand, signal amplification and noise reduction circuits have been used. However, most of these devices and circuits work in an active sampling mode, requiring frequent data acquisition and hence, entailing high-power consumption. In this scenario, a flexible and wearable event-triggered sensor with embedded signal amplification without an external power supply is of great interest. Here, we report a flexible two-terminal piezotronic n-p-n bipolar junction transistor (PBJT) that acts as an autonomous and highly sensitive, current- and/or voltage-mediated pressure sensor. The PBJT is formed by two back-to-back piezotronic diodes which are defined as emitter-base and collector-base diodes. Upon force exertion on the emitter side, as a result of the piezoelectric effect, the emitter-base diode is forward biased while the collector-base diode is reverse biased. Due to the inherent BJT amplification effect, the PBJT achieves record-high sensitivities of 139.7 kPa-1 (current-based) and 88.66 kPa-1 (voltage-based) in sensing mode. The PBJT also has a fast response time of <110 ms under exertion of dynamic stimuli ranging from a flying butterfly to a gentle finger touch. Therefore, the PBJT advances the state of the art not only in terms of sensitivity but also in regard to being self-driven and autonomous, making it promising for pressure sensing and other IoT applications.

Pyroelectric effect in high detectivity self-powered photodetector based on Cs2AgBiBr6

The ferroelectric perovskite material Cs2AgBiBr6 has received much attention because of its low poisonous nature and environmental stability. In this paper, we prepared high-quality Cs2AgBiBr6 thin films for self-powered photodetectors using a low-pressure-assisted method, investigated their optical, electrical, and pyroelectric properties, and characterized the film morphology and crystallization. The device modulates the photoelectric process without an external power supply, and has a maximum switching ratio of 1.72 × 106, a response rate of 0.158 A/W, a specific detectivity of 1.39 × 1011 Jones, an external quantum efficiency of 52.8 %, and a fast response time of 15.4/16.8 μs when irradiated with 532 nm light, which is much better than that of previous self-powered devices with the same material on/off ratio and specific detectivity. It is worth mentioning that the pyroelectric effect was observed in the infrared band. In addition, the devices exhibited high stability to water and oxygen in an air environment (25 °C, 60 % humidity), retaining more than 95 % of the initial performance after one month of placement. Our study demonstrates that the lead-free perovskite Cs2AgBiBr6 is a promising and environmentally friendly alternative for the preparation of highly stable self-powered photodetectors and is also of great research value in the field of pyroelectric detection.

Supplier selection for global service providers: a decision support system

In this paper, we develop a decision support system (DSS) aimed at solving a real-world supplier selection problem (SSP) for a global service provider (GSP) operating in the facility management (FM) industry. The GSP provides its customers with FM services, which are subcontracted to external suppliers selected on the basis of multiple criteria, like economic soundness, quality of service, capacity, and closeness. The SSP is formulated as a multi-objective generalized assignment problem, where the quality and the closeness of the selected suppliers are maximized, whereas a penalty produced by overcapacity assignments is minimized. The quality of each supplier is computed by applying a weighted sum method, resulting from a multi-criteria decision analysis in which the criteria weights are determined through an Analytic Hierarchy Process. The DSS is developed using a modular architecture with a relational database, a supplier evaluator, and a simulator, as well as an additional user-friendly interface. The simulator relies on a rolling horizon algorithm and three alternative configurations to assign contracts to suppliers. The effectiveness of the DSS is assessed by means of extensive computational experiments on historical data. The results show a significant average improvement of 25% compared to the solution adopted by the company.

Photopolymerized PAM/CTS/SA/Ca2+/TiO2 hydrogel for sustainable passive cooling

Evaporative cooling and radiative cooling are considered to be energy-saving and environmentally friendly cooling technologies. However, the evaporative cooling system requires complex external water supply equipment, and the radiative cooling is susceptible to weather, which hinder the practical application. Herein, TiO2 was used as the photo-initiator and spectral regulator, and a hydrogel integrating radiative cooling and evaporative cooling was prepared by combining photopolymerization with semi-acidification sol–gel transition method. The obtained hydrogel shows good mechanical strength (elongation at break > 600 %, and fracture stress > 200 kPa), high visible reflectance (>80.0 %) and emissivity in atmospheric window band (>90.0 %). At the same time, due to the introduction of hygroscopic agent CaCl2, it can replenish water itself at night. In outdoor experiment, the hydrogel showed a cooling effect of up to 12.5 °C, showing a significant potential for reducing energy consumption in cooling applications. In addition, the synthesis process of hydrogel is green, which aligns with environmental safety and sustainability goals. This study provides a new strategy for developing efficient, environmentally friendly, and low-cost passive coolers to reduce the global energy burden.

2D Layered Materials Based Triboelectric Self‐Powered Sensors

AbstractSensors play a crucial role in enhancing the quality of life, ensuring safety, and facilitating technological advancements. Over the past decade, 2D layered materials have been added as new sensing element in addition to existing materials such as metal oxides, semiconductors, metals, and polymers. 2D Layered materials are typically characterized by their single or few‐layer thickness and offer a high surface‐to‐volume ratio, exceptional mechanical strength, and unique electronic attributes. These properties make them ideal candidates for a variety of sensing applications. This review article focused on utilizing 2D layered materials in triboelectric nanogenerators (TENGs) for different sensing applications. The best part of TENG‐based sensing is that it is self‐powered, so no external power supply is required. The initial part of the review focused on the importance of the 2D layered materials and their innovative integration methods in TENGs. Further, this review discusses various sensing applications, including humidity, touch, force, temperature, and gas sensing, highlighting the impact of 2D layered materials in enhancing the sensitivity and selectivity of TENG sensors. The last part of the review discusses the challenges and prospects of TENG‐based self‐powered sensors.

Infrared emission properties of VO2 films fabricated with different oxygen flow ratios

Infrared (IR) camouflage materials are widely used to realize thermal camouflage by adjusting the IR emissivity (ε) of the target object. However, ε modulation without an external energy supply is still a great challenge. Self-regulating VO2 films with different IR emission properties are investigated by adjusting the oxygen flow ratio (O2%) and film thickness. The ε of VO2 films changes before and after the phase transition, and the Δε (the difference of ε before and after the phase transition) of films is different under different O2%, and the maximum Δε can reach 0.49. In addition, the difference temperature (ΔTIR) between the actual temperature (TA: the surface temperature of a standard silicon wafer measured by IR camera, which represents the actual temperature of VO2 samples.) and the IR trapping temperature (TIR: the temperature of VO2 samples measured by IR camera.) is greater than 35 °C after the phase transition. With the range of 1.6 %–2.2 % O2, the IR emission transition temperature (Tε-MIT) and hysteretic width (ΔTε-MIT) increase with increasing O2%. The thickness of the VO2 film affects the IR emission characteristics. The VO2 film is suitable for thermal camouflage materials and for IR anticounterfeiting.

Pt/CB-Catalyzed Chemoselective Hydrogenation Using In Situ-Generated Hydrogen by Microwave-Mediated Dehydrogenation of Methylcyclohexane under Continuous-Flow Conditions

Hydrogen gas (H2) has attracted attention as a next-generation clean energy source. Its efficient and safe preparation and utilization are crucial in both the industry and organic chemistry research. In this study, a Pt/CB (platinum on carbon bead)-catalyzed MW-mediated continuous-flow hydrogenation reaction was developed using methylcyclohexane (MCH) as the reducing agent (hydrogen carrier). Alkynes, alkenes, nitro groups, benzyl esters, and aromatic chlorides were chemoselectively hydrogenated using Pt/CB under MW-assisted continuous-flow conditions. This methodology represents a safe and energy-efficient hydrogenation process, as it eliminates the need for an external hydrogen gas supply or heating jackets as a heating medium. The further application of MW-mediated continuous-flow hydrogenation reactions is a viable option for the efficient generation and utilization of sustainable energy.

Model-based development of cell voltage control system for modified bio-electro-Fenton process

A modified bio-electro-Fenton (M−BEF) process with a cell voltage control system that improves the efficiency of organic removal and energy savings is demonstrated. The M−BEF process can accomplish bioelectricity generation, H2O2 production, and the Fenton reaction in a continuous-flow reactor. During synthetic wastewater treatment containing biodegradable (glucose) and recalcitrant (biphenyl) organic matter, the effluent chemical oxygen demand (COD) concentration was maintained between 2 and 6 mg L-1. To investigate the impact of different operating schemes on energy usage, model-based design (MBD) modeling and simulations were performed, which showed that COD removal efficiency without an external voltage supply was unstable at < 70 %. The automatic cell voltage control system saved 90 % of the power compared to the continuous cell voltage supply system. Further testing on more environmental samples and pollutants will enable real-time optimization of supplied power and wastewater treatment using the cell voltage control system.

A Low-Frequency Vibration Sensor Based on Ball Triboelectric Nanogenerator for Marine Pipeline Condition Monitoring.

Marine pipeline vibration condition monitoring is a critical and challenging issue, on account of the complex marine environment, while powering the required monitoring sensors remains problematic. This study introduces a vibration sensor based on a ball triboelectric nanogenerator (B-TENG) for marine pipelines condition monitoring. The B-TENG consists of an acrylic cube, polyester rope, aluminum electrodes, and PTFE ball, which converts vibration signals into electrical signals without the need for an external energy supply. The experimental results show that B-TENG can accurately monitor the frequency, amplitude, and direction of vibration in the range of 1-5 Hz with a small error of 0.67%, 4.4%, and 5%, and an accuracy of 0.1 Hz, 0.97 V/mm, and 1.5°, respectively. The hermetically sealed B-TENG can monitor vibration in underwater environments. Therefore, the B-TENG can be used as a cost-effective, self-powered, highly accurate vibration sensor for marine pipeline monitoring.

Extreme condition-tolerant stretchable flexible supercapacitor and triboelectric nanogenerator based on carrageenan-enhanced gel for energy storage, energy collection and self-powered sensing

As flexible electronics devices for energy storage, mechanical energy collection and self-powered sensing, stretchable flexible supercapacitor and triboelectric nanogenerator (TENG) have attracted extensive attention. However, it is difficult to satisfy the requirements of high safety and resistance to extreme conditions. Dual roles of mechanical and electrical enhancement of inorganic salt are put forward, and a carrageenan (CG) enhanced poly (N-hydroxyethyl acrylamide)/CG/lithium chloride/glycerol (PCLG) conductive gel is prepared by designing hydrogen bonding self-crosslinking and chain entanglement. A high concentration and rapid deposition strategy is proposed to prepare a PCLG gel-based stretchable flexible all-in-one supercapacitor for energy storage, and a single electrode PCLG gel-based TENG is designed for mechanical energy collection, self-powered strain and tactile sensing. The supercapacitor has high capacitance, excellent cycling stability. The TENG possesses efficient energy harvesting with high and stable output voltage and power density, and sensitive and stable self-powered strain and tactile sensing without external power supply. Even under extreme conditions such as low temperatures, self-healing after damage, prolonged placement, deformation, post-deformation, multiple continuous work, pinprick and burning, the supercapacitor and TENG still have excellent properties. Therefore, we provide novel ideas to design flexible supercapacitor and TENG used under extreme conditions for future wearable electronics.

Innovative Techniques for Optimizing Supply Chain Operations

Supply chain management is an approach used by firms to ensure that their business can be highly effective, and profitable and that operations run smoothly. This involves managing the movement of raw materials inwards and finished goods outwards. Logistics is a key component of this. It also involves managing the flow of products between companies, which can involve the movement of products between a manufacturer, a wholesaler, and a retailer. Supply chain management is therefore the integration of these flows between companies. Several innovative techniques can be used to optimize supply chain operations, particularly given recent advances in information technology. The function of logistics is known as activities that are related to the flow of products between companies, such as the transportation and warehousing of goods. Activities that take place within companies, such as inventory management and materials handling, are not considered to be logistical activities but part of the supply chain. The level of interest in supply chain management has risen quite dramatically over the last few years. This is partly due to advances in information technology, which have enabled closer integration of the supply chain. As well as increasing competition between companies, on both a national and an international level, has led to an increasing emphasis on the need for companies to concentrate on their core competencies, and to look to outside suppliers to provide other goods and services. This has led to the increased use of external suppliers.

Research on Hybrid Vibration Sensor for Measuring Downhole Drilling Tool Vibrational Frequencies

The vibration parameters during drilling play a critical role in enhancing drilling speed and ensuring safety. However, traditional downhole vibration sensors face limitations in their power supply methods, hindering widespread adoption. To address this challenge, our research introduces a novel solution: a hybrid downhole vibration sensor (HDV-TENG) utilizing triboelectric nanogenerators. This sensor not only enables the measurement of low- to medium–high-frequency vibrations using self-power but also serves to energize other downhole devices. We utilized a self-constructed vibration simulator to replicate downhole drilling tool vibrations and conducted a comprehensive series of sensor tests. The test results indicate that the frequency measurement bandwidth of the HDV-TENG spans from 0 to 200 kHz. Especially, the measurement errors for vibrations within the low-frequency range of 0 to 10 Hz and the high-frequency range of 10 to 200 k Hz are less than 5% and 8%, respectively. Additionally, the experimental findings regarding load matching demonstrate that the HDV-TENG achieves an output power level in the milliwatt range, representing a significant improvement over the output power of traditional triboelectric nanogenerators. Unlike traditional downhole vibration measurement sensors, HDV-TENG operates without requiring any external power supply, thereby conserving downhole space and significantly enhancing drilling efficiency. Furthermore, HDV-TENG not only offers a broad measurement range but also amplifies output power through the synergy of a triboelectric nanogenerator (TENG), piezoelectric nanogenerator (PENG), and electromagnetic power generator (EMG). This capability enables its utilization as an emergency power source for other micropower equipment downhole. The introduction of HDV-TENG also holds considerable implications for the development of self-powered underground sensors with high-frequency measurement capabilities.

Untethered, Dynamic Robotic Fabrics Enabled by Actively‐Rigid Variable Stiffness Fibers

AbstractA robot that uses fabrics as its core body material can be lightweight, compact, and highly flexible. Ideally, the robot's actuation, sensing, and structural support are provided by fiber‐based components, designed to integrate with the fabric's soft and conformable nature while preserving its fiber architecture. Typically, variable stiffness fibers are used for the structural elements, functioning as “bones” that can be turned on and off as needed. However, many variable stiffness fibers are passively‐rigid, only allowing the fabric to become soft when powered, while some require bulky external air or power supplies, making them untenable for untethered robotics. In this work, an electrically‐driven variable stiffness fiber is presented that performs a flat‐to‐curved geometry transition, providing a rigid load‐bearing structure when powered but remaining flexible otherwise. Design principles for pairing the actively‐rigid variable stiffness fiber with a materially compatible fiber‐based actuator are presented, and the actuator performance in different configurations is characterized. The variable stiffness fiber can be arranged into sturdy legs, stable enough for a robotic fabric to lift and hold its own battery pack and onboard electronics. This capability is demonstrated with a first‐of‐its‐kind fully‐untethered locomoting robotic fabric using two different quadruped gaits.

Self‐Powered Digital Angle Sensor Based on Triboelectric Signal for Variable Structure of Aircraft

AbstractThe rapid development of aircraft in recent years has attracted more attention, especially the issue of safe flight for aircraft. Some existing angle detection sensors are difficult to adapt to the development speed of the current aircraft due to the expensive price and large size, so there is an immediate need for new technology that can suit the current aircraft. Here, a self‐powered digital angle sensor that is compact, simple, and lightweight is introduced. This sensor eliminates the need for an external power supply and demonstrates highly sensitive signal detection at the volt level when the variable structure of the aircraft is working. The sensor is designed with a thickness of 7.3 mm, a volume of 16.6 cm3, and a weight of 9.85 g. Its lightweight and compact structure allows for seamless integration into aircraft without causing significant impact. The sensor not only provides real‐time monitoring the aircraft's variable structure deflection states, including deflection direction and angle but also alerts operators to any anomalies in deflection. Its small size and self‐powered capability make it an ideal solution for aircraft applications, enhancing safety and efficiency during flight.

Use of the Scepter Dual-Lumen Balloon Catheter for Transarterial Onyx Embolization of Cranial Dural Arteriovenous Fistulas

Dual-lumen balloon microcatheters allow for controlled anterograde flow of Onyx while providing proximal flow arrest, thereby obviating the need for a second microcatheter or Onyx plug formation. We sought to assess the safety and efficiency of the Scepter dual-lumen balloon microcatheter in trans arterial Onyx embolization of intracranial dural arteriovenous fistulas (DAVFs). We conducted a retrospective study of 36 patients with cranial DAVFs in which a Scepter balloon microcatheter was used between 2016 and2023. Our study comprised 36 patients, mostly male (n= 23, 63.8%) with a mean age of 60.8 years. Most DAVFs were in the occipital lobe (n= 24, 66.7%), and 50% had external carotid artery supply from the occipital artery. Eighteen (50%) of DAVFs were Cognard type III and IV, respectively. About one third (33.3%, n= 12) of the DAVFs drained into the transverse sigmoid junction, and 27.7% (n= 10) had direct cortical venous drainage into supratentorial or posterior fossa veins. Complete occlusion was obtained in 22 (61.1%) patients while partial occlusion was observed in 14 (38.9%) patients. One patient (2.8%) developed a retroperitoneal hematoma. At final follow-up, complete occlusion was observed in 21 (77.8%) and partial occlusion was observed in 8 (22.2%). Recurrence was observed in 4/30 (13.3%) patients, and retreatment was required in 6 (18.75%) cases. At midterm follow-up, our study showed low morbidity and modest complete occlusion rates using the Scepter for transarterial Onyx embolization of high-grade DAVFs.

Improved Lignin Conversion to High-Value Aromatic Monomers through Phase Junction CdS with Coexposed Hexagonal (100) and Cubic (220) Facets.

Photocatalysis has the potential for lignin valorization to generate functionalized aromatic monomers, but its application has been limited by the slow conversion rate and the low selectivity to desirable aromatic products. In this work, we designed the phase junction CdS with coexposed hexagonal (100) and cubic (220) facets to improve the photogenerated charge carriers' transfer efficiency from (100) facet to (220) facet and the hydrogen transfer efficiency for an enhanced conversion rate of lignin to aromatic monomers. Water is found as a sufficient external hydrogen supplier to increase the yields of aromatic monomers. These innovative designs in the reaction system promoted complete conversion of PP-ol to around 94% of aromatic monomers after 1 h of visible light irradiation, which shows the highest reaction rate and selectivity of target products in comparison with previous works. PP-one is a byproduct from the overoxidation of PP-ol and is usually difficult to be further cleaved to acetophenone and phenol as the desirable aromatic monomers. TEA was first identified in this study as a sacrificial electron donor, a hydrogen source, and a mediator to enhance the cleavage of the Cβ-O bonds in PP-one. With the assistance of TEA, PP-one can be completely cleaved to desirable aromatic monomer products, and the reaction time is reduced from several hours to 10 min of visible light irradiation.

A Study on the Mechanism and Properties of a Self-Powered H2O2 Electrochemical Sensor Based on a Fuel Cell Configuration with FePc and Graphene Cathode Catalyst Materials.

Conventional electrochemical sensors use voltammetric and amperometric methods with external power supply and modulation systems, which hinder the flexibility and application of the sensors. To avoid the use of an external power system and to minimize the number of electrochemical cell components, a self-powered electrochemical sensor (SPES) for hydrogen peroxide was investigated here. Iron phthalocyanine, an enzyme mimetic material, and Ni were used as a cathode catalyst and an anode material, respectively. The properties of the iron phthalocyanine catalyst modified by graphene nanoplatelets (GNPs) were investigated. Open circuit potential tests demonstrated the feasibility of this system. The GNP-modulated interface helped to solve the problems of aggregation and poor conductivity of iron phthalocyanine and allowed for the achievement of the best analytical characteristics of the self-powered H2O2 sensor with a low detection limit of 0.6 µM and significantly higher sensitivity of 0.198 A/(M·cm2) due to the enhanced electrochemical properties. The SPES demonstrated the best performance at pH 3.0 compared to pH 7.4 and 12.0. The sensor characteristics under the control of external variable load resistances are discussed and the cell showed the highest power density of 65.9 μW/cm2 with a 20 kOhm resistor. The practical applicability of this method was verified by the determination of H2O2 in blood serum.

Single-Source VLCP System Based on Solar Cell Array Receiver and Right-Angled Tetrahedron Trilateration VLP (RATT-VLP) Algorithm

A significant deployment limitation for visible light communication and positioning (VLCP) systems in energy- and light-source-restricted scenarios is the reliance of photodetectors (PDs) on external power supplies, compromising sustainability and complicating receiver charging. Solar cells (SCs), capable of harvesting and converting environmental light into electrical energy, offer a promising alternative. Consequently, we first propose an indoor VLCP system that utilizes an SC array as the receiver, alongside a right-angled tetrahedron trilateration visible light positioning (RATT-VLP) algorithm based on a single light source and multiple receivers. The proposed system uses an SC array in place of PDs, utilizing binary phase shift keying (BPSK) signals for simultaneous communication and positioning. In experiments, we verified the system’s error-free communication rate of 1.21 kbps and average positioning error of 3.40 cm in a 30 cm × 30 cm area, indicating that the system can simultaneously satisfy low-speed communication and accurate positioning applications. This provides a viable foundation for further research on SC-based VLCP systems, facilitating potential applications in environments like underwater wireless communication, positioning, and storage tank inspection.

Reducing carbon dioxide emissions when using methane-hydrogen fuel

AIM. To determine optimal modes for methane decarbonization, as well as to assess CO2 emissions during subsequent combustion of the pyrolysis gas, including together with the natural gas in various ratios.METHODS. The processes of thermochemical conversion of methane into hydrogen and condensed carbon in a reactor with external heating of the walls were considered. The thermal energy required for gas pyrolysis is obtained by burning a mixture of air and part of the pyrolysis gas, which is free from solid carbon particles. When performing numerical studies of pyrolysis processes, a kinetic model of one-dimensional flow of the reacting mixture was used with an external supply of thermal energy through the walls of an axisymmetric channel (tubular reactor).RESULTS. The mechanism of chemical interaction during the thermal decomposition of methane was developed, taking into account the formation of condensed carbon in the temperature range from 1000 to 1200 °C. The main energy indicators and the composition of pyrolysis gas were determined at various values of the pyrolysis temperature and the degree of carbon conversion.CONCLUSION. Carbon dioxide emissions from the combustion of pyrolysis gas, including together with the natural gas, were assessed. When developing pyrolysis technologies and applying them on an industrial scale, it is advisable to use part of the resulting pyrolysis gas with a high hydrogen content to provide thermal energy for the processes of thermal decomposition of the feedstock. According to the calculations, the share of this part reaches ≈ 35% of the total amount of pyrolysis gas. This approach, as opposed to burning the natural gas for this purpose, significantly reduces CO2 emissions. The combustion of the resulting pyrolysis gas, even without removing residual hydrocarbons, is characterized by currently quite acceptable CO2 emission factors of ≈ 7-25 t CO2/TJ.

Online Detection of Temperature Surge in Distributed Transmission Conductors Based on Fiber Optic Sensing Technology and Prediction Bias Correction

In an effort to overcome the shortcomings of transmittal line heat mutation detection, such as the need for long-term preset external power supply and susceptibility to electromagnetic interference, we study the online detection of heat mutation of dispersed transmittal conductor based on staple optic sensing technique and correction of sensor prediction bias, which solves the issue of cross allergy between heat and damage. Based on the staple optic sensing technique, the staple optic transducer is designed and the Brillouin rate divert of the dispersed transmittal line is calculated; on the basis of the relationship between the Brillouin rate divert and the heat, the heat measurement result of the dispersed transmittal line is obtained; in the radial basis function meshwork, the heat measurement result is inputted, the heat measurement deviation of the staple optic transducer is predicted, and the prediction deviation is corrected to get the corrected heat measurement result; by comparing the current heat measurement result with the historical heat data, the heat measurement result of the staple optic transducer is predicted. By comparing the current heat measurement outcome with the historical heat data, the heat of the dispersed transmittal line is detected online, and an alarm is issued when the heat morph exceeds the preset threshold value. Experiments have proved that: the method can availably calculate the Brillouin rate divert of dispersed transmittal conductors and complete the heat measurement of transmittal conductors; the method can availably correct the prediction deviation of transmittal conductor heat and improve the exact of heat measurement; the method can availably detect the heat mutation of dispersed transmittal conductors online, and the detection exact is high.