Self‐Generated Displacement Current of Triboelectric Nanogenerator for Cancer Therapy: Theory and Application

Advanced Materials

Triboelectric nanogenerators offer an environmentally friendly approach to harvesting energy from mechanical excitations. This capability has made them widely sought‐after as an efficient, renewable, and sustainable energy source, with the potential to decrease reliance on traditional fossil fuels. However, developing triboelectric nanogenerators with specific output remains a challenge mainly due to the uncertainties associated with their complex designs for real‐life applications. Artificial intelligence‐enabled inverse design is a powerful tool to realize performance‐oriented triboelectric nanogenerators. This is an emerging scientific direction that can address the concerns about the design and optimization of triboelectric nanogenerators leading to a next generation nanogenerator systems. This perspective paper aims at reviewing the principal analysis of triboelectricity, summarizing the current challenges of …

The growing popularity of the Internet of Things has led to increases in the need for renewable energy and sensor systems. Therefore, triboelectric nanogenerators (TENGs) have garnered significant attention as a novel form of energy production due to their lightweight nature, cost-effectiveness, high output, and versatility in terms of materials, low cost, and device configurations. TENGs have been studied for several uses, including self-powered sensing, biomedical, biomotion, healthcare monitoring, and robotic applications. The performance of TENG is drastically pretentious by the material because charge density (σ) is an inherent characteristic of the material. Metal-organic framework (MOF) materials possess robust charge-trapping capabilities, multifunctional structures, adjustable properties, and exceptional stability. These materials can be utilized or integrated as self-powered sensors of different kinds to …

Advanced Materials Technologies

Although natural evaporation absorbs substantial thermal energy from the ambient environment, efficiently utilizing this high‐entropy energy remains challenging. Here, the first water evaporation‐induced triboelectric nanogenerator is proposed. It only uses tap water to harvest low‐grade heat energy from the surroundings to convert it into electricity. The natural evaporation of the liquid can generate unintermittent electricity with an open‐circuit voltage of 382 V, a peak power of 0.42 mW, and three orders of magnitude enhancement up to 59.7 mJ mL−1 after consuming the same amount of tap water compared with the droplet‐based electricity generators. After which, the excellent power output lights 2 W LED and drives wearable electronic devices. This device also inhibits carbon steel materials' corrosion in solutions through the evaporation effect of the salt water on the spot. The present study provides novel …

Nano Energy

Tactile perception systems as the medium between the ambient environment and robotics lie in the heart of modern artificial intelligence. By providing different electronic readouts under various circumstances, they can give easily captured information for post-processing. However, for applications of most reported tactile perception systems, external location assistances are still needed. Here, as inspired by the platypus’ sixth sense, we developed a new kind of tactile perception system based on triboelectric sensors with the additional function from quantum rods. This terminal can be used as a single-electrode mode triboelectric nanogenerator for both location detection and vertical force sensing with high sensitivity and fast response. Moreover, by adding CdSe/CdS quantum rods into an imprinted polydimethylsiloxane film, different lateral stretching levels can be perceived by a modified luminescence. Supported …

Energy & Environmental Science

Controlling the motion of charge carriers in semiconductor materials is a fundamental strategy for achieving many functional devices, which is typically achieved by applying an external voltage source. Herein, using the electrostatic potential generated by a triboelectric material taken as a sliding “gate”, a functional current is generated across a semiconductor channel when the gate is moving in parallel to the dielectric surface. Systematic studies verify that the motion of the electrified “gate” induces the regional and dynamical doping of the semiconductor channel, thereby driving the carrier transport without applying an external voltage. This sliding-gated generator achieves mechanoelectric energy conversion based on the coupled triboelectrification effect and electrostatic field effect and is therefore termed as a field effect nanogenerator (FENG). It can output electrical currents with a waveform that follows well with …

Journal of Power Sources

High-frequency supercapacitors (HF–SCs) are promising electric energy storage devices and alternating current line filters. However, severe self-discharge of HF–SCs causes significant energy loss and limits their applications. Current self-discharge suppression methods for supercapacitors typically lead to decreased rate performance and hence cannot be applied to HF–SCs directly. In this work, barium titanate (BTO) nanoparticles are employed as an electrolyte additive for HF–SCs to reduce self-discharge. By adding BTO nanoparticles into the electrolyte, both leakage current and decay of open circuit voltage of the devices are reduced without sacrificing the specific capacitance and high-frequency response. At a charging voltage of 2 V, the leakage current is reduced by 49 % (3.91 vs. 1.98 μA), while the time for the voltage to drop from 2.0 to 1.0 V is extended by 4.5 times (2300 vs. 10240 sec). When the HF …

Small

Shelter forests (or shelter‐belts), while crucial for climate regulation, lack monitoring systems, e.g., Internet of Things (IoT) devices, but their abundant wind energy can potentially power these devices using the trees as mounting points. To harness wind energy, an omnidirectional fluid‐induced vibration triboelectric nanogenerator (OFIV‐TENG) has been developed. The device is installed on shelter forest trees to harvest wind energy from all directions, employing a fluid‐induced vibration (FIV) mechanism (fluid‐responding structure) that can capture and use wind energy, ranging from low wind speeds (vortex vibration) to high wind speeds (galloping). The rolling‐bead triboelectric nanogenerator (TENG) can efficiently harvest energy while minimizing wear and tear. Additionally, the usage of double electrodes results in an effective surface charge density of 21.4 µC m−2, which is the highest among all reported …

Advanced Materials

Recently, perovskite photodetectors (PDs) have been risen to prominence due to substantial research interest. Beyond merely tweaking the composition of materials, a cutting‐edge advancement lies in leveraging the innate piezoelectric polarization properties of perovskites themselves. Here, the investigation shows utilizing Ti3C2Tx, a typical MXene, as an intermediate layer for significantly boosting the piezoelectric property of MAPbI3 thin films. This improvement is primarily attributed to the enhanced polarization of the methylammonium (MA+) groups within MAPbI3, induced by the OH groups present in Ti3C2Tx. A flexible PD based on the MAPbI3/MXene heterostructure was then fabricated. The new device is sensitive to a wide range of wavelengths, displays greatly enhanced performances owing to the piezo‐phototronic coupling. Moreover, the device is endowed with a greatly reduced response time, down …

Energy & Environmental Science

Establishing maintenance-free wireless sensor networks for online monitoring of power transmission lines is crucial for realizing smart grids, exhibiting necessitating energy harvesters with compact volume, excellent robustness, and efficient, well-regulated output. This study introduces a hybrid magnetic energy harvester (HMEH), seamlessly integrating a magneto-mechanical energy conversion module, a non-contact rotational triboelectric nanogenerator (TENG) module, and an electro-magnetic generator (EMG) module for magnetic energy harvesting and self-powered sensing in power transmission lines. The HMEH converts magnetic energy into synchronized mechanical rotation using the magnetic phase difference principle and smoothly transforms it into a regulated electrical energy output. With a compact size of 5 cm × 5 cm × 3 cm and a light weight of 56 g, the HMEH showcases unprecedented volume and …

Small

Triboelectric nanogenerator (TENG) is a promising solution to harvest the low‐frequency, low‐actuation‐force, and high‐entropy droplet energy. Conventional attempts mainly focus on maximizing electrostatic energy harvest on the liquid‐solid surface, but enormous kinetic energy of droplet hitting the substrate is directly dissipated, limiting the output performance. Here, a dual‐mode TENG (DM‐TENG) is proposed to efficiently harvest both electrostatic energy at liquid‐solid surface from a droplet TENG (D‐TENG) and elastic potential energy of the vibrated cantilever from a contact‐separation TENG (CS‐TENG). Triggered by small droplets, the flexible cantilever beam, rather than conventional stiff ones, can easily vibrate multiple times with large amplitude, enabling frequency multiplication of CS‐TENG and producing amplified output charges. Combining with the top electrode design to sufficiently utilize charges at …

ACS Applied Materials & Interfaces

The global annual vegetable and fruit waste accounts for more than one-fifth of food waste, mainly due to deterioration. In addition, agricultural product spoilage can produce foodborne illnesses and threaten public health. Eco-friendly preservation technologies for extending the shelf life of agricultural products are of great significance to socio-economic development. Here, we report a dual-functional TENG (DF-TENG) that can simultaneously prolong the storage period of vegetables and realize wireless storage condition monitoring by harvesting the rotational energy. Under the illumination of the self-powered high-voltage electric field, the deterioration of vegetables can be effectively slowed down. It can not only decrease the respiration rate and weight loss of pakchoi but also increase the chlorophyll levels (∼33.1%) and superoxide dismutase activity (∼11.1%) after preservation for 4 days. Meanwhile, by …

Nature Communications

Harvesting biomechanical energy from cardiac motion is an attractive power source for implantable bioelectronic devices. Here, we report a battery-free, transcatheter, self-powered intracardiac pacemaker based on the coupled effect of triboelectrification and electrostatic induction for the treatment of arrhythmia in large animal models. We show that the capsule-shaped device (1.75 g, 1.52 cc) can be integrated with a delivery catheter for implanting in the right ventricle of a swine through the intravenous route, which effectively converts cardiac motion energy to electricity and maintains endocardial pacing function during the three-week follow-up period. We measure in vivo open circuit voltage and short circuit current of the self-powered intracardiac pacemaker of about 6.0 V and 0.2 μA, respectively. This approach exhibits up-to-date progress in self-powered medical devices and it may overcome the inherent …

Advanced Materials

Although dielectric elastomer actuators (DEAs) are promising artificial muscles for use as visual prostheses in patients with oculomotor nerve palsy (ONP), high driving voltage coupled with vulnerable compliant electrodes limits their safe long‐term service. Herein, a self‐healable polydimethylsiloxane compliant electrode based on reversible imine bonds and hydrogen bonds is prepared and coated on an acrylic ester film to develop a self‐healable DEA (SDEA), followed by actuation with a high‐output triboelectric nanogenerator (TENG) to construct a self‐powered DEA (TENG‐SDEA). Under 135.9 kV mm−1, the SDEA exhibits an elevated actuated strain of 50.6%, comparable to the actuation under DC power. Moreover, the mechanically damaged TENG‐SDEA displays a self‐healing efficiency of over 90% for 10 cycles. The TENG ensures the safe using of TENG‐SDEAs and an extraocular‐muscle‐like actuator …

Chemical Engineering Journal

Triboelectric nanogenerators (TENGs) and lithium-ion batteries (LIBs) play an important role in the field of clean energy as energy conversion and storage devices respectively. It is vital to fabricate efficient transport between TENGs and LIBs for promoting the development in combined energy systems. This work constructs an efficient energy transport system between the contact-energy contact-separation TENG (CCS-TENG) and the LIB by introducing power management based on a short-circuit contact in-situ. Such synergy system satisfies the needs of improving the efficient connection between TENGs and LIBs, durability and miniaturization of energy unit. The short-circuit contact in-situ guarantees the maximum energy output of CSS-TENG in every contact-separation cycle and the energy density is as high as 131.1 mJ m−2 cycle−1, although the electrode of CCS-TENG is only 10 cm2. Moreover, the TENG cycle …

Advanced Functional Materials

The utilization of unmanned aerial vehicles (UAVs) is on the rise across various industries. In such a scenario, the issue of flight safety for these UAVs becomes increasingly paramount. Currently, UAVs exhibit shortcomings in flight attitude perception compared to more mature manned aircraft, especially concerning the position sensing of flight actuation, which poses significant safety risks. Mature position monitoring solutions for flight actuation used in manned aircraft cannot be directly integrated into systems of UAV due to compatibility issues. This necessitates the development of new position sensing technologies to address this challenge. Triboelectric nanogenerators, with their advantages of miniaturization, self‐powering capabilities, and the ability to generate voltage‐level electrical signals, are chosen to form a part of the position detection system for sensors in UAVs. In this study, a self‐powered …

As one of the few self-powered instruments and devices, triboelectric nanogenerators (TENGs) have been developed for more than 10 years since its invention in 2012. With wide material selections and diverse design structures, and without having to use an external power supply, TENG has been applied in many key technologies. By the end of 2022, more than 16,000 researchers from 83 countries and regions around the world have authored scientific papers in TENG. In this review, we start from the theoretical principles and working mechanisms of TENG, and discuss its 5 major fields of application, namely, as self-powered sensors, high-voltage energy devices, blue energy devices, micro/nano-energy devices, and solid–liquid interface probes. Next, we review the breakthrough progress made using TENG as commercial products in the following fields: medical health, intelligent security, and marine energy …

Nano Energy

While triboelectric nanogenerated knitted fabrics are regarded as a state-of-the-art and reliable energy source for wearable electronics, there are two bottlenecks in their widespread applications: few mass-manufacturing strategies and low power output. Here, by mature weft-knitted technologies, a 3D single-faced jacquard pile fabric TENG (SJPF-TENG) with the merits of high surface pile density, excellent comfort and breathability, good thermal insulation property, and superior durability, is mass-produced. Based on the high-density pile structure (about 16128 piles per cm2), the surface area of pile fabrics is 42.2 times that of the plain structure, which endows the SJPF-TENG with higher electrical outputs and good detection precision. With a peak power density of 1.4 W m−2 (dozens of times that of conventional textile-based TENGs), the SJPF-TENG is capable of lighting up 1392 light-emitting diodes, powering …

IEEE Sensors Journal

Accurate rainfall monitoring carries significant importance across meteorological and hydrological domains. However, existing sensors face numerous challenges, including issues related to accuracy, stability, and limited measurement range, particularly during heavy rain events. Here, an innovative droplet-based triboelectric nanogenerator (D-TENG) rain gauge is proposed to overcome the above challenges. It incorporates a saddle-shaped rainfall bearing plate designed to channel rainwater for regular dripping onto the D-TENG, thereby generating electrical signals for droplet enumeration. The feasibility of the D-TENG rain gauge is substantiated through the analyses of the stability of the electrical signal (short-circuit current) and droplet weight. Experimental results illustrate the effective measurement range of the D-TENG rain gauge as 0-243.1 mm/h, with the relative error in calculated rainfall intensity within ±4 …

Nano Energy

Multi-direction, irregularity, low-grade, the dynamic characteristics of low-grade airflow energy are prominent that making it difficult to collect. Here, we propose a vibration-coupled triboelectric nanogenerator (VC-TENG) induced by vortex to achieve from weak to ultra-strong vibration, thus effectively converting low-grade airflow energy into vibrational mechanical energy, and then electric energy. The transferred charge and short-circuit current increases is 47 and 26.9 times due to designed vortex structure, and the resonant response time is 2 s at a speed of 4.1 m/s. A VC-TENG unit delivers a peak power of 4.5 mW under a load resistance of 500 MΩ. A grouping of applied demonstrations of self-powered system validates the practicality and durability of VC-TENG. This work offers a practical strategy for harvesting low-grade airflow energy, and is a promising distributed power technologies for self-powered monitoring …

Advanced Materials Technologies

Accurate data acquisition from flexible sensors placed on deformable 3D freeform surfaces is of critical importance for many applications, such as wearable electronics, human‐machine interfaces, and soft robotics. However, the mechanical coupling between the sensor and the deformable subject surface to bending and stretching deformations can significantly reduce the accuracy of the acquired data. This study combines a polyimide (PI) micropore isolation layer (PIL) and serpentine electrodes with a flexible piezoresistive sensor to mitigate the issue of mechanical coupling. As a mechanical buffer to distribute the external pressure and reduce the strain concentration, the PIL can avoid the bending interference for bending curvature up to 256 m−1, while maintaining a high sensitivity of S > 21.5 kPa−1. The serpentine electrode design further allows the sensor to reliably acquire data in the presence of stretching …

Advanced Materials Technologies

Despite significant growth in the field of tissue engineering over the past decades, non‐invasive, non‐destructive methods to characterize the cellularisation of grafts are lacking. Here, in a proof‐of‐concept study, a non‐invasive magnetic resonance imaging method, diffusion tensor imaging (DTI), within acellular and cellularised vascular grafts is investigated. Using decellularised porcine carotid grafts, smooth muscle cells are cultured dynamically for two weeks with terminal time points at day 3, 7, and 14. Grafts are fixed at each time point and investigated by DTI in an ex vivo set up. Semi‐quantitative histology is used as a ground truth for collagen, elastin, and cell density changes over time. DTI‐derived metrics, namely the fractional anisotropy, mean diffusivity, and tractography, are significantly different between day 3 and day 7 grafts and distinguish between acellular and cellularised grafts. Specifically …

Advanced Materials Technologies

Though photon‐induced electron donor features of fluorescent proteins (FPs) in solution suggest them as excellent photosensitizers, their poor stability upon device fabrication/operation is the today's frontier. This relates to their immediate denaturation in water‐free/less environments: inorganic/organic device interfaces and/or organic solvent surroundings. This study provides a fresh solution with a family of hybrid FPs, in which the peripheral carboxylic groups of archetypal FPs ‐superfolder green fluorescent protein (sfGFP) and mCherry‐ are transformed into alkoxysilane groups, enabling a straightforward integration with surprising stabilities over months in devices – arbitrary n/p‐type semiconducting metal oxide/FP/organic‐solvent electrolyte interfaces – attributed to the formation of an ion‐silica shell around the FP. This further allowed to understand the charge injection mechanism applying steady‐state/time …

Advanced Materials Technologies

3D continuous mesoscale architectures of nanomaterials possess the potential to revolutionize real‐time electrochemical biosensing through higher active site density and improved accessibility for cell proliferation. Herein, 3D microporous Ti3C2TX MXene biosensors are fabricated to monitor antibiotic release in tissue engineering scaffolds. The Ti3C2TX‐coated 3D electrodes are prepared by conformal MXene deposition on 3D‐printed polymer microlattices. The Ti3C2TX MXene coating facilitates direct electron transfer, leading to the efficient detection of common antibiotics such as gentamicin and vancomycin. The 3D microporous architecture exposes greater electrochemically active MXene surface area, resulting in remarkable sensitivity for detecting gentamicin (10–1 mM) and vancomycin (100–1 mM), 1000 times more sensitive than control electrodes composed of 2D planar films of Ti3C2TX MXene. To …

Advanced Materials Technologies

Optical curvature sensors find regular use in deformation analysis, typically requiring pre‐calibration and post‐processing of the gathered data. In this work, a self‐calibrated curvature sensor based on flexible holographic metasurfaces operating in the visible range is presented. In contrast to existing solutions, the sensor can be fabricated independently from the target objects and provides an immediate readout of their curvature. The sensor consists of distinct patterned areas that create images of a reference scale and of a position indicator, which shift with respect to each other, as the metasurface is deformed. The results of this sensor are validated with an external calibration and critically discuss the types of deformations that the sensor can detect. This feature makes the sensor particularly attractive for applications where real‐time curvature monitoring is essential, such as in robotics, biomechanics, and …

Advanced Materials Technologies

The electrically‐directed, isothermal response of liquid crystal elastomers (LCEs) to an applied electric field is a compelling approach to realize spatially tailorable, sequence‐controllable, and high‐frequency deformation. The electromechanical response is facilitated by coating aligned LCEs with compliant electrodes. Upon application of an electric field, the electrodes attract and generate Maxwell stress. The directional difference in moduli for aligned LCEs produces directional deformation of the material and does not require mechanical bias or framing. Here, LCEs prepared from a newly reported thiol‐ene reaction are explored as DEAs with improved mechanical and dielectric properties. This report details that incorporating a difunctional liquid crystalline monomer composed of allyl ether functional groups reduces Young's modulus, increases the dielectric constant, and improves cyclic recovery compared to an …

Advanced Materials Technologies

Breath ammonia is an essential biomarker for patients with many chronic illnesses, such as chronic kidney disease (CKD), chronic liver disease (CLD), urea cycle disorders (UCD), and hepatic encephalopathy. However, existing breath ammonia sensors fail to compensate for the impact of breath humidity and complex breathing motions associated with a human breath sample. Here, a multimodal breath sensing system is presented that integrates an ammonia sensor based on a thermally cleaved conjugated polymer, a humidity sensor based on reduced graphene oxide (rGO), and a breath dynamics sensor based on a 3D folded strain‐responsive mesostructure. The miniaturized construction and module‐based configuration offer flexible integration with a broad range of masks. Experimental results present the capabilities of the system in continuously detecting diagnostic ranges of breath ammonia under real …

Advanced Materials Technologies

Silicate glasses have played a major role as structural and functional materials in human civilization since ancient Egypt. Despite their widespread use and importance in modern society, silica glasses with complex geometries are only fabricated in automated processes using 3D printing. Here, the volumetric printing of silica‐based glasses with tunable multimaterial and microstructural control is reported. Volumetric printing enables complex shaping of photo‐reactive resins in a few seconds using illumination techniques analogous to those employed for medical imaging. Particle‐filled and phase‐separating resins are used as photo‐reactive feedstock that is quickly printed in 3D and subsequently converted into silica glasses through conventional heat treatment. Using rheology and imaging techniques, it is shown that the design of the resin is crucial to print complex geometries with high shape fidelity. The …

Advanced Materials Technologies

Wearable thermoelectric devices are widely used due to their ability to generate heat and cool rapidly without the need for bulky external equipment. Researchers have explored methods to enhance flexibility and stretchability by incorporating liquid metal as an electrode. However, the challenge lies in the low thermal conductivity of the polymer, which hampers heating and cooling performance. Traditional methods, like molding and spraying, increase the thickness of both liquid metal and polymer channels, but this added thickness does not significantly improve the device's stretchability.[1, 2] To overcome these issues, this paper proposes a stretchable thermoelectric device (STED), which offers improved heating and cooling capabilities, as well as enhanced stretchability. To enhance the thermal conductivity of the polymer, Ag powder with varying particle sizes is mixed with the material. Additionally, the liquid …

Advanced Materials Technologies

The High Target Utilisation Sputtering technique (HiTUS) is of interest for industrial processes, including in roll‐to‐roll manufacturing. This study marks the first application of HiTUS to thermoelectric materials, exemplified by bismuth telluride. The HiTUS technique separates the sputtering power into the plasma power and the target power, with additional kinetic energy in the sputtering particles from the applied electrical field, thus enabling a much wider sputter parameter space to modify the film performance. This study investigates how plasma power, target power, and substrate bias in HiTUS intricately influence crystal orientation/size, elemental composition, surface morphology, and other film properties. These factors subsequently affect carrier density/mobility, and consequently the thermoelectric performance of the bismuth telluride film. These deposited films reach a power factor of 6.5 × 10−4 W m−1 K−2 with a …

Advanced Materials Technologies

Three‐Dimensional (3D) printed porous materials hold the potential for various soft sensing applications due to their remarkable flexibility, low density, and customizable geometries. However, developing versatile and efficient fabrication methods is crucial to unlock their full potential. A novel approach is introduced by combining Digital Light Processing (DLP) 3D printing and freeze‐drying to manufacture deformable cryogels featuring intricate morphologies. Photocurable hydrogels based on Poly(3,4‐ethylenedioxythiophene)Polystyrene sulfonate (PEDOT:PSS), Polyethylene glycol Diacrylate (PEGDA) and Ethylene Glycol (EG) are successfully printed and lyophilized. In this way, porous cryogels with tailorable properties are achieved. Microporosity varies from 68% to 96%, according to the chemical composition. Ultra‐soft cryogels with a compressive modulus of 0.13MPa are fabricated by adding a reactive …

Advanced Materials Technologies

With the development of wearable and wireless electronic devices, the triboelectric nanogenerator (TENG) is attracting interest as a candidate for portable power. Many studies are conducted to increase the surface charge density of the TENG, such as external charge pumping or external electron excitation strategies. However, there are limitations in that another additional external energy source is required. Here, a TENG–capacitor (TC) coupling system that can maximize energy generation and storage efficiency within a limited volume is proposed. Density functional theory calculations indicate that the electric field induced on capacitor increases the fermi energy of positive triboelectric material, resulting in more charge transfer between two triboelectric materials. TC coupling system enhances TENG output performance and the capacitor charging rate in a virtuous cycle. This study provides new insights into …

Advanced Materials Technologies

Setting the magnetization and its properties in magnetic materials and films is of the utmost fundamental and technological importance for magnetic applications and devices. Magnetic permeabilities in a material are generally defined by the acting magnetic anisotropies together with an applied magnetic field. Here, deterministic switching of the effective dynamic magnetic properties is demonstrated by tunable networks of magnetic domain walls. By perforating magnetic films, a reversible switching between different magnetization states is achieved. Due to the resulting local effective dynamic fields for the changed domain configurations, different zero‐field permeability spectra are attained for the same material structure. Using local configurational magnetic resonances confined by magnetic domain walls, deterministic switchable bimodal dynamic behavior is achieved. Dynamic magnetooptical Kerr microscopy with …

Advanced Materials Technologies

In a daily environment, several vibration energies have low amplitude and broad range of frequencies, and it is crucial to harvest them efficiently in a single triboelectric nanogenerator (TENG). Here, a multi‐degree of freedom (DOF) vibration system is coupled with TENG to make several resonant frequencies in a single device. When the number of DOF increases in the system, the number of resonant frequencies also increases. These resonant frequencies are calculated by MATLAB software using the masses and spring constant of DOF vibration system. With the masses of 20 g and the spring constant of 82.712 N m−1, it is found that 1‐DOF has one resonant frequency (20.47 Hz), 2‐DOF has two resonant frequencies (12.63 and 33.17 Hz), and 3‐DOF has three resonant frequencies (9.12, 25.55, and 36.87 Hz). At each resonant frequency, the displacement of all weight layers increases due to the constructive …

Advanced Materials Technologies

It is crucial to develop functional electronic materials that can be processed from green solvents to achieve environmentally sustainable and cost‐efficient printing fabrication of organic electronic devices. Here, the design and cost‐efficient synthesis of two hydrophilic and emissive conjugated polymers, TQ‐OEG and TQ2F‐OEG, are presented, which are rendered hydrophilic through the grafting of oligo(ethylene glycol) (OEG) solubilizing groups onto the thiophene‐quinoxaline conjugated backbone and thereby can be processed from a water:ethanol solvent mixture. The results show that the introduction of the OEG groups enables for a direct dissolution of salts by the neat polymer for the attainment of solid‐state ion mobility. These properties are utilized for the design and development of light‐emitting electrochemical cells (LECs), the active materials of which can be solution cast from a water:ethanol‐based ink. It …

Advanced Materials Technologies

Nonwoven media used as electret air filters are often embedded with charges to improve particle capture efficiency. These charged filters are invariably exposed to low surface tension fluids such as oils and alcohols leading to charge loss. In this study, filtration media are endowed with charge protection through increased surface repellency using melt additives that can migrate to the surface during processing. Nonwovens containing fluorochemical melt additives are produced, and examined to determine the relationship between surface chemistry, isopropyl alcohol (IPA) repellency, resultant charge retention, and filtration characteristics. Surface fluorine/carbon (F/C) ratios of ≈0.2 are sufficient to protect filtration performance from vapor discharging methods. Samples with bulk additive loadings of 1.2% or higher are found to achieve the necessary repellency to resist discharging independent of the migration state …

Advanced Materials Technologies

Mimicking tissue‐oriented organization in vitro has been extensively studied in recent years, using both natural and synthetic materials in combination with external magnetic fields to establish anisotropic conditions. Here, a new combination between magneto‐responsive anisometric PEG microgels and collagen hydrogels is explored to establish anisotropic in vitro models. Different sizes of PEG microgels are tested to assess the impact of both width and aspect ratio on the formation and alignment of collagen hydrogels. Results show that the key properties of collagen hydrogels, regarding fibrillogenesis, rheological properties, and fiber diameter are kept consistent upon the combination with PEG microgels. Furthermore, partial collagen fiber alignment is observed when larger (width 10 µm) PEG microgels are employed and magnetically aligned. In vitro studies show cell alignment within the anisotropic collagen …

Advanced Materials Technologies

With their unique combination of characteristics – an energy density almost 100 times that of human muscle, and a power density of 5.3 kW kg−1, similar to a jet engine's output – Nylon artificial muscles stand out as particularly apt for robotics applications. However, the necessity of integrating sensors and controllers poses a limitation to their practical usage. Here, a constant power open‐loop controller is reported based on machine learning. It shows that the position of a nylon artificial muscle without external sensors can be controlled. To this end, a mapping is constructed from a desired displacement trajectory to a required power using an ensemble encoder‐style feed‐forward neural network. The neural controller is carefully trained on a physics‐based denoised dataset and can be fine‐tuned to accommodate various types of thermal artificial muscles, irrespective of the presence or absence of hysteresis. This …

Advanced Materials Technologies

Energy storage devices with liquid‐metal electrodes have attracted interest in recent years due to their potential for mechanical resilience, self‐healing, dendrite‐free operation, and fast reaction kinetics. Gallium alloys like Eutectic Gallium Indium (EGaIn) are appealing due to their low melting point and high theoretical specific capacity. However, EGaIn electrodes are unstable in highly alkaline electrolytes due to Gallium oxide dissolution. In this letter, this bottleneck is addressed by introducing chemically stable films in which nanoscale droplets of EGaIn are coated with trace amounts of graphene oxide (GO). It is demonstrated that a GO to EGaIn weight ratio as low as 0.01 provides enough protection for a thin film formed by GO@EGaIn nanocomposite against significantly acidic or alkaline environments (pH 1‐14). It is shown that GO coating significantly enhances the surface stability in such environments, thus …

Advanced Materials Technologies

Although natural evaporation absorbs substantial thermal energy from the ambient environment, efficiently utilizing this high‐entropy energy remains challenging. Here, the first water evaporation‐induced triboelectric nanogenerator is proposed. It only uses tap water to harvest low‐grade heat energy from the surroundings to convert it into electricity. The natural evaporation of the liquid can generate unintermittent electricity with an open‐circuit voltage of 382 V, a peak power of 0.42 mW, and three orders of magnitude enhancement up to 59.7 mJ mL−1 after consuming the same amount of tap water compared with the droplet‐based electricity generators. After which, the excellent power output lights 2 W LED and drives wearable electronic devices. This device also inhibits carbon steel materials' corrosion in solutions through the evaporation effect of the salt water on the spot. The present study provides novel …