Portable Electronic Devices Research Articles

Molecular Dynamics Analysis of Li+/Mg2+ Transport Mechanism in COF Membranes with Flexible Oxygen-Containing Side Chains

Lithium is currently used in a wide range of portable electronic devices. With the rapid growth of the electric vehicle sector, lithium has become an essential resource. In this work, the influence of different lengths and types of oxygen-containing side chain in COF membranes on the Li+/Mg2+ separation performance were explored via molecular dynamic simulations. The transport mechanism was elucidated through analysis of the interaction mechanism, density distribution map, potential of mean force (PMF), and dehydration number of ions during their passage through the membranes. Simulation results indicate that COF-4EO membrane shows high separation performance for Li+/Mg2+ mixture, the flexible side chain of EO provides a jumping site for Li+ ions, and the transport energy barrier in the membrane for Li+ ions is low, which enhances the screening effect into the pore. Moreover, Mg2+ ions are more difficult to dehydrate water from their hydration layer and then enter into the membrane. This work would give some insight for designing of COF membranes with well ion separation performance.

Wide-temperature and high-voltage Li||LiCoO2 cells enabled by a nonflammable partially-fluorinated electrolyte with fine-tuning solvation structure

Efficient, safe, and reliable energy output from high-energy-density lithium metal batteries (LMBs) at all climates is crucial for portable electronic devices operating in complex environments. The performance of corresponding cathodes and lithium (Li) metal anodes, however, faces significant challenges under such demanding conditions. Herein, a nonflammable electrolyte for high-voltage Li||LCO cells has been designed, including partially-fluorinated ethyl 4,4,4-trifluorobutyrate (ETFB) as the key solvent, guided by theoretical calculations. With this ETFB-based electrolyte, Li||LCO cells exhibit enhanced reversible capacities and superior capacity retention at an elevated charge voltage of 4.5 V and a wide operating temperature range spanning from −60 °C to 70 °C. The cells achieve 67.1% discharge capacity at −60 °C, relative to room temperature capacity, and 85.9% 100th-cycle retention at 70 °C. The outstanding properties are attributed to the LiF-rich interphases formed in the ETFB-based electrolyte with a fine-tuned solvation structure, in which the coordination environment in the vicinity of Li+ cations and the distance between anion and solvents are subtly adjusted by introducing ETFB. This solvation structure has been mutually elucidated through joint spectra characterizations and atomistic simulations. This work presents a new strategy for the design of electrolytes to achieve all-climate reliable and safe application of LMBs.

Standardization of portable electronic devices as a strategy for preventing e-waste generation

Standardization of portable electronic devices as a strategy for preventing e-waste generation

Untethered Autonomous Holonomic Mobile Micromanipulator for Operations in Isolated Confined Spaces

With increasing miniaturization of portable electronic devices, conventional positioning systems have become inefficient in terms of size and energy consumption. As workspaces shrink, the need for precise autonomous manipulation in confined and isolated environments increases, particularly in areas such as electronics and biological assemblies. Herein, an autonomous, untethered, holonomic, mobile micromanipulator driven by piezoelectric actuators with nanometer resolution is developed. The micromanipulator comprises a driving circuit, single‐board computer, battery, manipulator, and small camera; it is lightweight (515 g), compact (90 × 116 × 104 mm), and untethered, capable of independently operating in confined and dangerous spaces for humans. The micromanipulator can autonomously position a single object with a positioning error of 0.18 ± 0.51 mm and an angular deviation of −0.4° ± 1.2°, utilizing image recognition, machine learning, and visual feedback. Moreover, the micromanipulator is verified to function in extreme conditions that simulate draft chambers and clean benches, where it successfully performs circuit mounting in confined space. The device can arrange droplets under microscopy for applications in chemical and biomedical fields, demonstrating its versatility and precise positioning capabilities. Additionally, its multi‐scale applications are explored from centimeters to sub‐micrometers and adjusted to the magnification capabilities of various microscopes.

The Application of Integrated Force and Temperature Sensors to Enhance Orthotic Treatment Monitoring in Adolescent Idiopathic Scoliosis: A Pilot Study

Orthosis-wearing compliance is crucial for achieving positive treatment outcomes in patients with adolescent idiopathic scoliosis (AIS), for whom 23 h of daily wear is typically prescribed. However, self-reported compliance is subjective and often based on patients’ memory, leading to inaccuracies. While portable electronic devices have been developed to objectively monitor compliance, relying solely on temperature or force data can be insufficient. This study introduced a novel method that integrated both force and temperature data to estimate orthosis-wearing compliance. Twelve patients (eight females and four males) diagnosed with moderate AIS were included. Each patient was prescribed a thoracic-lumbar-sacral orthosis equipped with an integrated force and temperature sensor system. After one month of orthotic treatment, self-reported wear time averaged 17.8 ± 6.2 h/day, while the sensor indicated an average wear time of 13.3 ± 5.0 h/day. Most patients overestimated their compliance. Nighttime was the most common period for orthosis wear (6.1 h/day), whereas compliance during school hours (2.8 h/day) and after-school hours (3.7 h/day) was lower. The integration of force and temperature sensors provides a more comprehensive understanding of orthosis compliance. Future studies with larger samples and longer monitoring periods are needed to investigate the correlation between compliance and treatment outcomes.

Comparative Analysis of Regression Methods for Estimation of Remaining Useful Life of Lithium Ion Battery

Lithium batteries play a critical role in modern technological applications, including electric vehicles and portable electronic devices. Ensuring accurate estimation of their remaining useful life is essential to improve system efficiency and reliability. This study focuses on predicting the remaining useful life of lithium batteries using advanced regression methods. Data were collected from lithium battery charge-discharge cycles, encompassing key operational parameters such as voltage, current, and temperature. The analysis employed several regression models, including linear regression, lasso regression, and Ridge regression, to identify relationships between these parameters and battery life. The models were evaluated based on estimation accuracy, with Root Mean Square Error (RMSE) as the primary performance metric. The findings demonstrate that regression methods can effectively capture non-linear relationships between input variables and the remaining useful life, with lasso and Ridge regression showing superior performance in reducing prediction errors. These results underscore the potential of regression-based approaches in providing robust and reliable estimations of battery life. The conclusions highlight the importance of these models for developing predictive battery management systems, which can optimize battery performance and extend their operational lifespan across various applications. This research establishes a solid foundation for future studies on intelligent battery health monitoring and management.

Surface Sulfurization and Self‐Reconstruction Strategy for Decorating Carbon Nanofibers to Fabricate Sheet‐Like NiCo2S4 Grown on Ni3S2 Electrode

In this study, transition metal sulfide‐based binder‐free hybrid electrodes were grown in‐situ on Ni foam using a simple hydrothermal method. However, it still remains a challenge for designing a heterostructure with sufficient electroactive sites to improve electrochemical performance. Herein, effects of CNF‐wrapped NSNCS on Ni foam binder‐free composites were investigated for developing high‐performance, low‐cost supercapacitors. By avoiding the use of additive binding polymers, the purity of the electrodes was enhanced, resulting in excellent electrochemical behavior. The prepared binder‐free CNF@NSNCS composite electrode exhibited an ultrahigh specific capacitance of 2739 F/g at a current density of 1 A/g, with superior capacitance retention charge‐discharge cycle stability of 100% over continuous 14,000 cycles at 10 A/g. Furthermore, an asymmetric supercapacitor (ASC) was assembled using CNF@NSNCS binder‐free composites as the positive electrode and Activated carbon (AC) as the negative electrode. The assembled devices demonstrated superior electrochemical performance, delivering a high energy density of 77.5 Wh/kg at a power density of 748.4 W/kg. This work may contribute to advancing the development of low‐cost, high‐performance energy storage applications for the next generation of portable electronic devices.

Innovative Organic Electrolytes for Enhanced Energy Density and Performance in Supercapacitors

ABSTRACTSupercapacitors, known for their high‐power energy storage capabilities, have garnered significant attention due to their rapid charge–discharge cycles and extended life span. To expand their application in fields such as electric vehicles, renewable energy systems, and portable electronic devices, the development of advanced electrolytes that can boost energy density, power density, and overall performance is crucial. This study introduces a novel electrolyte formulation comprising lithium chloride in ethylene glycol and Magnesium Acetate in methanol. These formulations are designed to address existing challenges and enhance supercapacitor efficiency. The study reports impressive specific capacitance values (Csp = 582, 360, and 224 F/g), specific energy (SE = 323, 200, and 124 Wh/kg), and specific power (SP = 11 628, 7200, and 1322 W/kg) for lithium chloride, magnesium acetate, and zinc chloride electrolytes, respectively. These findings open new avenues for developing optimal and sustainable energy storage solutions in an increasingly electrified world. Continued research in this domain is expected to unlock the full potential of supercapacitors, contributing to a cleaner and more energy‐efficient future.

Polymer-based Solid Electrolyte and Electrode/Electrolyte Interfacial Contact Characteristics Affecting Lithium-ion Battery Performance

Lithium-ion batteries (LIBs) are now embedded in peoples daily life usage including portable electronic devices and electric vehicles. The demand for further developed LIBs with better energy storage, energy transport, safety, etc. However, the commercial and conventional LIBs use liquid electrolyte widely. Although it provides excellent ionic conductivity, its poor mechanical strength often induces the growth of dendrite, which is often considered as the primary factor that causes short circuits, undesired side reactions, and reductions in energy capacity. To address these issues, polymer-based solid-state electrolytes (SSEs) were developed. It exhibits comprehensive properties and can cooperate with other materials to resolve their defects, creating various novel materials in different scenarios. This paper covers four commonly used polymers in the fabrication of SSEs and key parameters indicating their energy density and stability. It provides a brief introduction to the reader about the characteristics of varying polymer-based electrolytes, and how these characteristics, combined with interface contact, affect the overall battery performance.

The Influence of Carbon Nanotube Composites of Precious Metals and Non-precious Metal Oxides on the Electrode Performance of Supercapacitors

As the problems of energy shortage and environmental pollution are increasingly escalating, the development of efficient and sustainable energy storage technologies has become extremely important. Among these technologies, supercapacitors are receiving significant attention due to their relatively high energy density and power density, making them a promising solution for future energy needs. The unique combination of fast charge-discharge capability, long cycle life, and reliability makes supercapacitors attractive in fields such as portable electronic devices, electric vehicles, and renewable energy integration. In particular, composite materials containing carbon nanotubes and metal oxides are of great research interest in improving the performance of supercapacitors. For example, incorporating non-precious metal oxides (such as manganese oxide and nickel oxide) or precious metal oxides (such as ruthenium oxide) into carbon-based materials can significantly enhance electrochemical performance. An appropriate loading quantity of active materials plays a crucial role in achieving high specific capacitance. Furthermore, different composite preparation techniques have a significant impact on the microstructure of the materials, thereby markedly changing the electrochemical characteristics of the electrode and affecting its overall performance in energy storage systems.

Influences of carbon nanotubes as electrode materials on the energy storage for lithium-ion batteries

Due to inherent theoretical capacity limitations and safety issues associated with commonly used anode materials in lithium-ion batteries, carbon nanotubes (CNTs), with their unique one-dimensional tubular structure and superior mechanical, electrical, and thermal properties, can partially address these deficiencies and enhance lithium storage capacity. Therefore, this paper concentrates on the impacts of carbon nanotubes as electrode materials on energy storage for lithium-ion batteries. It discusses three aspects in detail: the use of CNTs as direct anode materials, as composite anode materials, and as flexible electrode materials. Each application will be examined in terms of its specific advantages, existing challenges, and corresponding solutions to improve battery performance. The paper also evaluates the role of CNTs in enhancing the electrochemical stability, improving cycle life, and achieving higher power densities, which makes them highly promising for next-generation energy storage solutions, particularly for portable and flexible electronic devices. Additionally, the unique ability of CNTs to form a highly conductive network facilitates efficient charge transport and reduces internal resistance, further contributing to the overall performance of the battery. Future research directions may focus on optimizing the synthesis methods and improving the interface interactions between CNTs and other active materials, to fully leverage their properties for enhanced safety, higher efficiency, and lower costs. As such, carbon nanotubes are seen as key materials that could play an important role in meeting the growing demand for advanced energy storage systems.

A Carbon Nanotube Transistor Based on Buried-Gate Structure.

From the discovery of carbon nanotubes to the ability to prepare high-purity semiconductor carbon nanotubes in large quantities, the large-scale fabrication of carbon nanotube transistors (CNT) will become possible. In this paper, a carbon nanotube transistor featuring a buried-gate structure, employing an etching process to optimize the surface flatness of the device and enhance its performance, is presented. This CNT thin-film transistor has a current switching ratio of 104, a threshold voltage of around 1 V, and a mobility that can reach 6.95 cm2/V·s, indicating excellent electrical performance. The device achieves operational targets at low voltage, facilitating the development of small and portable electronic devices.

Enhanced buck-boost converter performance using a snubber circuit and advanced semiconductor devices

Conventional buck-boost converter designs often suffer from efficiency losses and performance degradation due to switching transients and voltage spikes. To address these challenges, we propose the incorporation of a snubber circuit, which is designed to absorb and mitigate these detrimental effects. The study involves the design, implementation, and experimental evaluation of the proposed enhanced buck-boost converter. The analysis focuses on the impact of the snubber circuit on key performance metrics, including efficiency, thermal behavior, and electromagnetic interference (EMI) reduction. The experimental results indicate that the snubber circuit significantly reduces voltage spikes and switching losses, leading to improved converter efficiency and reliability. These findings provide valuable insights for optimizing converter designs in a variety of applications, from renewable energy systems to portable electronic devices, ultimately contributing to the advancement of power electronics technology. Finally, the performance of the proposed converter is analyzed using advanced semiconductor devices.

Performance metrics and mechanistic considerations for the development of 3D batteries.

There is an urgent need for improved energy storage devices to enable advances in markets ranging from small-scale applications (such as portable electronic devices) to large-scale energy storage for transportation and electric-grid energy. Next-generation batteries must be characterized by high energy density, high power density, fast charging capabilities, operation over a wide temperature range and safety. To achieve such ambitious performance metrics, creative solutions that synergistically combine state-of-the-art material systems with advanced architectures must be developed. The development of 3D batteries is a promising solution for achieving these targets. However, considerable challenges remain related to integrating the various components of a battery into an architecture that is truly 3D. In this Review, we describe the status of 3D batteries, highlight key advances in terms of mechanistic insights and relevant performance descriptors, and suggest future steps for translating current concepts into commercially relevant solutions.

One‐Pot Synthesis of a Nitrogen‐ and Iodine‐Doped Graphene Composite for Energy Storage Applications

AbstractWith the growth of power generation, portable electronic devices are gaining more attention toward energy storage devices, preferably supercapacitors. In this, the surface of graphene was functionalized with conductive polymer by in situ polymerization of pyrrole (PPy) and doping of iodine via hydrothermal method. Doping iodine (potassium triiodide) and nitrogen (polypyrrole) from their respective precursors made GNI composition more suitable for energy storage applications. The synthesized GNI composite showed the maximum specific capacitance of 200 F g−1 at 1.0 Ag−1 with an efficient specific energy of 22.5 Wh kg−1 and specific power of 1800 W kg−1 in a symmetrically arranged two‐electrode Swagelok type cell. The durability of the synthesized composite was analyzed by cyclic stability at current density 10 Ag−1, retaining up to 85% of its initial capacitance after 10,000 repetitive charge‐discharge cycles. The in situ polymerization of pyrrole with the insertion of iodine makes graphene composition more conductive than control graphene, showing a specific capacitance of 111 F g−1 at 1.0 Ag−1. The one‐pot synthetic approach is a simple, easy, and efficient route toward supercapacitor applications. This approach will provide an easy way to introduce N and I to graphene compositions for various applications, including energy storage materials.

A novel microfluidic chip based on an impedance-enhanced electrochemical immunoassay

Electrochemical immunoassays have been employed in clinical diagnostics for a considerable duration. The use of microspheres or microbeads as carriers for biomarkers serves as a foundational platform for biochemical testing. In conventional electrochemical immunoassays, constant potential instruments are predominantly utilized to measure current variations on the electrode surface, thereby achieving optimal sensitivity. However, the bio-modified electrode surface introduces complexities in cleaning, separation, and other applications. We present a novel microfluidic device based on an impedance-enhanced electrochemical immunoassay that introduces a continuous fluid quantitative platform that employs freely moving multiplex beads containing antigens bound to magnetic and dielectric micro/nanobeads, which are measured using an electrochemical impedance biosensor, all within a one-way microchannel of a microfluidic chip. This device utilizes antibody-coated magnetic beads and dielectric beads conjugated with detection antibodies for quantitative analysis in conjunction with portable electronic devices. Additionally, we have developed an innovative algorithm for microbead analysis based on the modeling of coplanar electrodes to detect viral proteins. This unique bead-based technology has been successfully integrated into a microfluidic chip and proved to have effectively detected COVID-19. The proposed device leverages bead-based technology and electrical impedance characteristics, offering substantial potential for integration with miniaturized electronic elements. This microfluidic device facilitates simple, rapid, efficient, portable, compact, and cost-effective high-throughput measurements, thereby enhancing clinical diagnostic capabilities for emerging infectious diseases.

Improved electrical and thermoelectric properties of electrodeposited Bi1-x Sb x nanowire networks by thermal annealing.

Arrays of thermoelectric nanowires embedded in organic films are attracting increasing interest to fabricate flexible thermoelectric devices with adjustable dimensions and complex shapes, useful for sustainable power sources of portable electronic devices and wireless sensor networks. Here, we report the electrochemical synthesis of interconnected bismuth-antimony (Bi1-x Sb x ) nanowires (with 0.06 < x < 0.15) within the branched cylindrical nanopores of polycarbonate membranes. The influence of temperature and magnetic field on the electrical and thermoelectric properties was studied by considering electric and thermal currents flowing in the plane of the films. We show that short annealing times with temperature up to 250 °C of the nanowire-based nanocomposite lead to a large increase in the thermoelectric power, reaching values up to -80 μV K-1 at room temperature, which are comparable to those of bulk Bi-Sb alloys. In addition, we report Hall effect measurements on crossed nanowires, made possible for the first time by the remarkable electrical connectivity of the nanowire network. These measurements, combined with variations in temperature and under the magnetic field of the electrical resistance, indicate that the interconnected networks of Bi1-x Sb x nanowires after thermal annealing behave like n-type, narrow band gap semiconductors. Overall, the electrical and thermoelectric properties near the ambient temperature of the heat-treated Bi1-x Sb x nanowire networks are similar to those of bulk polycrystalline Bi-Sb alloys, which are well-known thermoelectric materials exhibiting optimal performance near and below room temperature.

Germanium nanocrystal non-volatile memory devices: fabrication, charge storage mechanism and characterization.

The widespread proliferation and increasing use of portable electronic devices and wearables, and the recent developments in artificial intelligence and internet-of-things, have fuelled the need for high-density and low-voltage non-volatile memory devices. Nanocrystal memory, an emergent non-volatile memory (NVM) device that makes use of the Coulomb blockade effect, can potentially result in the scaling of the tunnel dielectric layer to a very small thickness. Since the nanocrystals are electrically isolated, potential charge leakage paths via localized defects in the thin tunnel dielectric can be substantially reduced, unlike that in a continuous polysilicon floating gate structure. The equivalent oxide thickness of the tunnel dielectric layer can be further reduced by using high dielectric constant materials to replace silicon dioxide, thus giving rise to faster program/erase during device operation and better charge retention performance. In this review on germanium (Ge) nanocrystal NVM devices, a brief historical perspective of semiconductor NVM devices will first be presented. Fabrication techniques for synthesizing Ge nanocrystals and those for Ge nanocrystal capacitor and transistor devices in a tri-layer insulator gate stack structure will then be presented. Investigations into the charge storage mechanism and electrical performance of Ge nanocrystal memory devices will be discussed. The application of a scanning probe microscopy-based nano-characterization method, that of scanning capacitance spectroscopy/microscopy, to analyze carrier charging in Ge nanodots and the passivation of hole and electron traps after forming gas annealing will be highlighted. This has led to a better understanding of the charge storage mechanism in the Ge nanocrystals. The use of high dielectric constant materials in the tri-layer gate structure to minimize Ge penetration into the substrate during the high temperature annealing synthesis step will also be presented in this article. Traps/defects within the Ge nanocrystals play an important role in the charge storage and retention mechanism. This article will also show how the trap energy level could be modulated using high dielectric constant materials in the tunnel dielectric and cap oxide layers for improved device performance.

Heterostructure Design of Amorphous Vanadium Oxides@Carbon/Graphene Nanoplates Boosts Improved Capacity, Cycling Stability and High Rate Performance for Zn2+ Storage

AbstractAs a promising power supplier, flexible aqueous zinc ion batteries (AZIBs) have drawn great attention and been demonstrated potential applications in portable electronic devices, yet their capacity, stability, and rate performance are severely limited by cathode materials. Herein, a spontaneous encapsulation and in situ phase transformation strategy is proposed for the construction of heterostructured amorphous vanadium oxide@carbon/graphene (A‐VOx@C/G) nanoplates as highly stable and efficient cathode materials for Zn2+ storage. In this design, A‐VOx provides abundant active sites with rapid ion diffusion channels and robust tolerance against ion insertion/extraction, while N‐doped carbon encapsulation and interlaced graphene network ensure efficient electron transfer. The mechanisms respectively for phase transformation during electrochemical amorphization and charge storage during cycling are investigated in detail. The as‐prepared A‐VOx@C/G achieves an outstanding electrochemical performance with 429 mAh g−1 at 0.5 A g−1, 73% retained at 20 A g−1 (315 mAh g−1), and excellent stability over 2000 cycles at 20 A g−1 (91% retention). Moreover, quasi‐solid‐state AZIBs assembled from A‐VOx@C/G cathode exhibit high flexibility and can sustain large mechanical deformation without performance degradation. It is believed that this study provides a guideline toward designing high‐performance cathode materials for AZIBs through structure optimization.

Generating a Full Cycle of Alternative Current Using a Triboelectric Nanogenerator for Energy Harvesting.

The triboelectric nanogenerator (TENG) has emerged as a promising technology for efficiently converting ambient mechanical energy into electrical energy. Among various designs, the disk-based rotational TENG has demonstrated significant potential, as it can continuously harvest energy in a sliding mode via a grating mechanism. However, horizontal mechanical energy is more common than rotational energy in many practical applications. Herein, the present study introduces a novel device: the double horizontal linear-to-rotational triboelectric nanogenerator (DHLR-TENG). This innovative approach utilizes a gear system to convert horizontal linear mechanical energy into electrical energy. The experimental results revealed that the DHLR-TENG produces a full cycle of alternating current (AC) when integrated into an electrical circuit. It consistently delivers robust performance with an open-circuit voltage of 544 V, a short-circuit current of 61.16 µA, and a maximum power output of 33.27 mW. Additionally, the device durability, capable of withstanding over 1,000,000 cycles, makes it highly effective for powering small electronic devices, such as charging capacitors and illuminating commercial LEDs. The DHLR-TENG's versatility and efficiency mark it as a major advancement in energy harvesting, with broad implications for powering portable electronic devices in a wide range of environments.