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Researchers have created a modern infrared (IR) sensor that is both super-sensitive and highly flexible. This remarkable device possesses impressive properties of exceptional sensitivity (24,000%), high responsiveness (1.25 A/W), and fast response time (3 ms). This innovation stands out for its unique construction: an ultrathin layer of lead sulfide (PbS) deposited on a standard Whatman filter paper. This design achieves a photo-current 32 times greater than previous record-holding PbS thin films. The key advantage is its unmatched flexibility. This sensor can bend and flex without breaking, maintaining its IR detection capabilities even after enduring extreme bending cycles. This breakthrough paves the way for a new era of wearable IR photo sensors, flexible electronics, and medical applications. [ABSTRACT FROM AUTHOR]

The conversion of ambient mechanical vibrations into electricity using piezoelectric nanogenerators (PENGs) has garnered significant attention from researchers over the past few years, in light of its potential in wearable applications. The high flexibility and significant ferroelectricity of poly(vinylidene fluoride) (PVDF) make them the most promising candidates for PENG applications among polymer piezoelectric materials. In the present work, NiO nanoparticles were incorporated in different ratios into a PVDF matrix, and their potential for use in piezoelectric nanogenerators was investigated. The PVDF/NiO (5 wt.%) nanocomposite PENG exhibited the highest electrical output, with a 2.8-fold increase in open-circuit voltage and short-circuit current observed as compared to a bare PVDF-based PENG. However, a further increase in the compositional ratio of NiO led to a decrease in PENG output. The improved piezoelectricity in the PVDF/NiO (5 wt.%) nanocomposite is attributed to the enhanced polar phases and improved ferroelectricity of PVDF. Further confirmation of the improved piezoresponse was explored by measurement of the piezoelectric coefficient (d33) and dielectric study of the nanocomposites. The PENG electrical output was further simulated using the finite elemental method in COMSOL Multiphysics 5.5. The simulated results matched well with the experimental output, which confirmed the improved electrical performance of the PVDF/NiO nanocomposite-based PENGs. The enhanced performance of the nanocomposite PVDF film is attributed to the higher β phase in the PVDF. The efficiency of the PENG devices in motion-sensing applications was also explored. Different output voltage signals corresponding to different movements of the nanocomposite-based PENGs make the device compatible with sensor applications. [ABSTRACT FROM AUTHOR]

Highlights: The review provides a brief overview of the basic structure, operating mechanism, and key performance indicators of flexible graphene field-effect transistors. The review details the preparation strategy of flexible graphene field-effect transistors focusing on material selection and patterning techniques. The review analyzes the latest strategies for developing wearable and implantable flexible biomedical sensors based on flexible graphene field-effect transistors. Flexible electronics are transforming our lives by making daily activities more convenient. Central to this innovation are field-effect transistors (FETs), valued for their efficient signal processing, nanoscale fabrication, low-power consumption, fast response times, and versatility. Graphene, known for its exceptional mechanical properties, high electron mobility, and biocompatibility, is an ideal material for FET channels and sensors. The combination of graphene and FETs has given rise to flexible graphene field-effect transistors (FGFETs), driving significant advances in flexible electronics and sparked a strong interest in flexible biomedical sensors. Here, we first provide a brief overview of the basic structure, operating mechanism, and evaluation parameters of FGFETs, and delve into their material selection and patterning techniques. The ability of FGFETs to sense strains and biomolecular charges opens up diverse application possibilities. We specifically analyze the latest strategies for integrating FGFETs into wearable and implantable flexible biomedical sensors, focusing on the key aspects of constructing high-quality flexible biomedical sensors. Finally, we discuss the current challenges and prospects of FGFETs and their applications in biomedical sensors. This review will provide valuable insights and inspiration for ongoing research to improve the quality of FGFETs and broaden their application prospects in flexible biomedical sensing. [ABSTRACT FROM AUTHOR]

Brain-computer interfaces (BCIs) represent a cutting-edge field in neuroengineering, facilitating direct communication between the brain and external devices. With applications ranging from the study of neuroscience to medical diagnosis and therapy, virtual reality, and cognitive augmentation, BCIs are at the forefront of technological advancement. Traditional rigid neural probes used in BCIs face challenges in maintaining long-term, stable recordings at the single-neuron level. Furthermore, achieving high electrode density while minimizing flexural rigidity remains a challenge with conventional rigid materials. In this perspective, we emphasize the importance of spatiotemporal scalability in the advancement of neural probes. We discuss the necessary material properties to achieve high spatiotemporal scalability, which is critical for long-term stability in neural recordings and for increasing electrode counts and density. We review recent developments in flexible and soft material systems, as well as fabrication strategies to meet these challenges. Our analysis highlights the potential of flexible and soft electronics to overcome existing limitations and realize the full potential of next-generation BCIs. [ABSTRACT FROM AUTHOR]

Aircraft in both the commercial and defense sectors undergo significant disassembly in order to access and inspect critical structures and components. To limit the extent of disassembly needed and thus increase system availability, the concept of mobile robotic inspection has been notionally discussed for over 20 years. Notably this interest in mobile robotic inspection extends beyond aircraft to include civil infrastructure, pipelines, and nuclear plants where some robotic platforms are currently in use. However, the unique challenges associated with complex aircraft systems and structures remain to be addressed. With advancements in the fields of durable polymers, autonomous materials, flexible electronics, tailorable actuation, and others, soft robotics are an increasingly viable solution to the challenge of inspection in access-limited spaces. This perspective article will overview key advancements in pertinent technical areas and highlight scientific barriers to wide-spread use and acceptance of soft robotics for aircraft inspection. [ABSTRACT FROM AUTHOR]

This paper comprehensively analyses the specific absorption rate (SAR) for an ultra-wideband (UWB) wearable antenna designed for body-centric communication applications. The study is motivated by the extent of electromagnetic radiation in our surroundings, raising worries about health for wireless device users and wearable devices that utilize UWB technology. The proposed antenna is made of a foam substrate having a dielectric constant of 1.07, a thickness of 2 mm with a dimension of 36 × 48 × 2 mm 3 . The designed structure optimizes UWB (3.1–10.6 GHz) in connotation with the ISM band of 2.4 GHz. The proposed antenna works well over the wide frequency range resulting in a bandwidth of 11.53 GHz and a total gain of 8.05 dBi. An excellent impedance matching is obtained by creating a stub at the feed point which gives the maximum value of S11 as − 44.88 dB. The analysis focuses on the SAR values to measure the rate of electromagnetic energy absorption by human tissues over 1 and 10 g by constructing an equivalent three-layer body phantom model. The results indicate that the proposed antenna exhibits SAR values well within the limits set by international standards of 1.6 W/kg averaged over 1 g of tissue and 2 W/kg for 10 g of tissue, while maintaining efficient radiation characteristics across the UWB spectrum. [ABSTRACT FROM AUTHOR]

A flexible, low-cost, UV photodetector has been fabricated using multiwall carbon nanotubes-tungsten oxide ( MWCNTs-WO 3 ) composite buckypaper. A low-cost facile hydrothermal process has been used to synthesize the photo active material. The synthesized composite buckypaper has been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The synergic effect of wideband gap WO 3 and high conductivity of MWCNTs, result in high responsivity UV photodetector. The fabricated device has been characterized by current–voltage measurement with and without UV illumination. The linear current–voltage characteristics were observed under dark and 365 nm UV light illumination and have obvious differences. The photoresponsivity R at 0.2 V bias is ∼ 60 A/W under 650 μ W / cm 2 of UV light. The device exhibits the highest detectivity of ∼ 7.3 × 10 11 Jones and an EQE (%) of 20,384 under UV illumination at a low bias voltage. The synthesized buckypaper composite has the potential to be used in ultraviolet photodetector applications. [ABSTRACT FROM AUTHOR]

With the rise of wearable device applications, efficient energy storage devices with flexible properties have become an important research direction. Among these devices, supercapacitors with high stability and instantaneous high power output for energy storage systems have attracted research attention. In this study, we demonstrate the possibility of applying nitrogen-doped chromium (Cr:CrN) thin films to flexible electrostatic double-layer capacitor (EDLC) electrodes. Chromium (Cr) electrodes undergo nitriding through sputtering, imparting interstitial defect characteristics and a nanoporous structure to the Cr layers. The resulting Cr:CrN layer not only exhibits excellent electrical conductivity but also enhances the faradaic process due to its interstitial defect properties. Experimental findings demonstrate that EDLCs employing Cr:CrN thin film electrodes exhibit exceptional performance, including fast charging, high current density tolerance, and cost-effectiveness. On glass substrates, the device achieves a maximum specific capacitance value of 6.69 mF/cm2 and an energy density of 0.33 Wh/m2 at an operating voltage of 3 V. Meanwhile, the flexible device demonstrates a specific capacitance value of 0.90 mF/cm2 and an energy density of 0.02 Wh/m2 at an operating voltage of 2 V. These results underscore the significant potential of Cr:CrN films as electrodes for EDLCs, particularly in flexible applications. [ABSTRACT FROM AUTHOR]

Wearable electronics powered by flexible energy storage devices have captured global attention. Under low-temperature conditions, unfortunately, solidification of flexible hydrogel electrolyte and decreased pseudo-capacity of these devices largely hamper their practical use. In this study, photothermally-active Prussian blue (PB) was introduced onto poly(3,4-ethylenedioxythiophene)/polyacrylamide (PEDOT/PAM) networks to address the challenges of electrolyte solidification and degraded pseudo-capacitance for flexible all-in-one device at low temperatures. The as-constructed PB/PEDOT/PAM hydrogel device delivers stable electrochemical performance and remarkable mechanical property with 1652% elongation. Importantly, this hydrogel device well retains its flexibility in cold environment with a freezing point below −30 °C. The incorporation of PB extends the voltage range to 1.5 V as a single device, thus significantly enhancing the electrochemical performance as an all-in-one integrated device. Benefitting from the outstanding photo-to-thermal conversion ability of embedded PB nanocubes, the temperature of the assembled all-in-one PB/PEDOT/PAM device increased from −20 to 17.7 °C after solar-light irradiation for only 5 min. Moreover, the degraded pseudo-capacitance was subsequently boosted to 287.1% of its original capacitance at −20 °C. This study establishes a connection between flexible all-solid-state hydrogel devices and photothermally enhanced pseudo-capacitors in freezing environments, thereby expanding the potential applications of multi-functional pseudo-capacitors. [ABSTRACT FROM AUTHOR]

We investigated the techno-economic feasibility and power supply potential of enhanced geothermal systems (EGS) across the contiguous United States using a new subsurface temperature model and detailed simulations of EGS project life cycle. Under business-as-usual scenarios and across depths of 1–7 kilometers, we estimated 82,945 GW and 0.65 GW of EGS supply capacity with lower levelized cost of electricity than conventional hydrothermal and solar photovoltaic projects, respectively. Considering the scenario of flexible geothermal dispatch via wellhead throttling and power plant bypass, these estimates climbed up to 184,112 GW and 44.66 GW, respectively. The majority of EGS supply potential was found in the Western and Southwestern regions of the United States, where California, Oregon, Nevada, Montana, and Texas had the greatest EGS capacity potential. With advanced drilling rates based on state-of-the-art implementations of recent EGS projects, we estimated an average improvement of 25.1% in the levelized cost of electricity. These findings underscored the pivotal role of flexible operations in enhancing the competitiveness and scalability of EGS as a dispatchable renewable energy source. [ABSTRACT FROM AUTHOR]

The Ferromagnetic Resonance (FMR) phenomenon, marked by the selective absorption of microwave radiation by magnetic materials in the presence of a magnetic field, plays a pivotal role in the development of radar absorbing materials, high speed magnetic storage, and magnetic sensors. This process is integral for technologies requiring precise control over microwave absorption frequencies. We explored how variations in resonance fields can be effectively modulated by adjusting both the shape and stress anisotropies of magnetic materials on a flexible substrate. Utilizing polyethylene-naphthalate (PEN) as the substrate and Permalloy (Ni79Fe21, noted for its positive magnetostriction coefficient) as the magnetic component, we demonstrated that modifications in the aspect ratio and bending repetitions can significantly alter the resonance field. The results, consistent with Kittel’s equation and the predictions of a uniaxial magnetic anisotropy model, underscore the potential for flexible substrates in enhancing the sensitivity and versatility of RF-based magnetic devices. [ABSTRACT FROM AUTHOR]

Two novel chiral nematic cellulose nanocrystal (CNC) composite films composed of CNCs, gluconic acid (GA), polyvinyl pyrrolidone or polyacrylamide (CNC-GA-PVP and CNC-GA-PAM) were fabricated mainly by evaporation-induced self-assembly process. The visible iridescent color and chiral nematic structure of the obtained CNC-based films could be readily regulated by altering the content of GA in a wide color range. Both CNC composite films possessed good tensile strength. Worthy to be mentioned, the CNC-GA-PAM films exhibited rather high flexibility (elongation reached 222.53%) and could be curled into any shape, indicating the effective contribution of the polymer cross-linked networks from the non-ionic PAM. The reversible humidity responses were also observed for both CNC films with good sensitivity, probably due to the high hygroscopicity of GA. In addition, the CNC-GA-PAM films revealed exceptional water resistance without losing the regular chiral structure and structural color of CNCs. The influences of the content of tougheners and adding way of the polymers on the properties of CNC films were further investigated. This work presents a novel strategy for construction of multifunctional CNC-based nanomaterials for various applications. [ABSTRACT FROM AUTHOR]

Oil pollution poses serious threat to environment and ecological system. Using porous materials for absorption and separation is an effective method to treat oil polluted water. In this study, a methyltriethoxysilane (MTES) based flexible silica aerogel monolith with novel pearls-like hierarchical porous structure was prepared via ambient pressure drying. The robust and high-porosity aerogel network was composed of macropores and three-dimensionally interconnected pearls-like secondary silica particles that possess both micropores and mesopores. The hierarchical porous aerogel exhibited remarkable hydrophobic/oleophilic and oil absorption/desorption properties, with a high oil separation rate and a high absorption capacity of 5.5–8 g/g for various oils. The aerogel also showed good durability and excellent recyclability in different oil absorption/desorption test cycles. Furthermore, the absorbed oil could be effectively and rapidly removed by evaporation or pumping to realize the continuous oil/water separation. The largest flux of n-hexane pumped out from the aerogel was evaluated to be 4350 ml/h, and the separation efficiency was as high as 97.8–99.2%, indicating that the flexible pearls-like hierarchical porous silica aerogel could be a promising choice for oil/water separation. [ABSTRACT FROM AUTHOR]

We developeda facile method to construct flexible, freestanding three dimensional hierarchical electrodes that consist of graphene encapsulated one-dimensional conducting polyaniline (PANi)@MnO2 coaxial nanowires grown on electrospun carbon nanofibers (denoted as G-PANi@MnO2/ECNFs). A combination of XRD, SEM, and TEM techniques were used to characterize the structures of G‑PANi@MnO2/ECNFs. Electrochemical measurements confirmed that such nanostructured composites possessed higher electrochemical capacitance than that of each individual component due to synergistic effects. The G-PANi@MnO2/ECNFs electrode exhibited extremely high specific capacitance (1364.3 F/g at 0.3 A/g) and superior cycling stability (89.2% retention rate after 2000 cycles) in a 1 M Na2SO4 aqueous solution. The excellent electrochemical performance of such nanoscale architectured electrodes provides a new route to develop flexible, freestanding, and high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

The present contribution introduces the design, methods, functionalities, and capabilities of the open-source multibody dynamics code Exudyn, which has been developed since 2019. The code has been designed for rigid and flexible multibody systems, with a focus on performance for multicore desktop processors. It includes script-language-based modeling and it is intended to be used in science and education, but also in industry. The open-source code is available on GitHub and consists of a main C++ core, a rich Python interface including pre- and postprocessing modules in Python, and a collection of rigid and flexible bodies with appropriate joint, load, and sensor functionality. Integrated solvers allow explicit and implicit time integration, static solution, eigenvalue analysis, and optimization. In the paper, the code design, structure, computational core, computational objects, and multibody formulations are addressed. In addition, the computational performance is evaluated with examples of rigid and flexible multibody systems. The results show the significant impact of multithreading especially for small systems, but also for larger models. [ABSTRACT FROM AUTHOR]

A flexible, transparent and polarization-insensitive metasurface absorber (MA) with dual-broadband feature is proposed. The MA consists of absorption layer, transparent flexible polyvinyl chloride (PVC) dielectric layer, and indium tin oxide (ITO)/polyethylene terephthalate (PET) bottom plate. The dual-broadband characteristics are studied by transmission-line theory, numerical simulation and experiment. The experimental results indicate that over 90% absorptivity under the planar case is achieved in 10.85–26.01 GHz and 44.86–56.67 GHz, corresponding relative bandwidth are 82.23% and 23.26%, respectively. The light transmittance is 63.3%. Both theoretical analysis and simulated results are good accordance with the experiment. The influence of structural parameters on the dual-broadband absorption performance is studied. Moreover, the analysis of the impedance matching theory, surface current, magnetic field and electric field distributions and power loss density are given to explain the dual-band absorption mechanism. The proposed dual-broadband MA maintains good angular stability whether in planar (30°) or conformal (20°) cases. The MA has simple structure, high optical transparency and flexibility, it promises to be a good candidate for electromagnetic (EM) shielding room observation windows, touch panel controls, radio-frequency identification systems and transparent radio-frequency devices. [ABSTRACT FROM AUTHOR]

In the present work, a flexible piezoelectric generator (PEG) based on (Li, Ta, Sb) modified (K, Na) NbO3 (KNNLTS)/poly(vinylidene fluoride) (PVDF) flexible composite film is fabricated. The prepared films are characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The addition of KNNLTS in the PVDF polymer matrix has resulted in the enhancement in the ferroelectric, piezoelectric, dielectric and piezoelectric output performance. The maximum generated open circuit peak-to-peak voltage from the PVDF/KNNLTS PEG was 36.58 V, which is almost four times higher than the voltage obtained using pure PVDF. The performance of the PEG is also tested under different human body motions, such as fist beating, elbow bending, and quenching and fist opening, which shows the maximum voltage of 5.48, 4.12 and 1.72 V, respectively. The present work demonstrated that high-performance PEG can be developed by modifying KNN ceramics by suitable dopants that can be used in self-powered and wearable devices. [ABSTRACT FROM AUTHOR]

SiOx-based resistive switching (RS) cells composed of Cu as the active electrode were fabricated on flexible muscovite mica flakes using DC and radio frequency magnetron sputtering techniques. In one set of the metal–insulator–metal (MIM) devices, Cu-nanoparticles (Cu-NPs) have been embedded into the SiOx layer and their RS properties have been compared with the devices without the Cu-NPs. All the devices exhibited forming free bipolar RS characteristics. Room temperature DC current–voltage (I–V) measurements suggest improved resistance windows for the Cu-NP-embedded MIM devices. Analysis of the DC I–V characteristics suggests electrochemical metallization-driven RS, where current conduction follows Ohmic and space-charge-limited conductions mechanism for low and high resistance states, respectively. The resistance windows of the Cu-NPs-embedded MIM structures tested for multiple cycles do not degrade under different bending conditions, indicating their mechanical robustness for potential flexible device applications. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) are considered as a crucial energy source for flexible and wearable electronics. Pseudo-planar heterojunction (PPHJ) OSCs simplify the solution preparation and morphology control. However, non-halogenated solvent-printed PPHJ often have an undesirable vertical component distribution and insufficient donor/acceptor interfaces. Additionally, the inherent brittleness of non-fullerene small molecule acceptors (NFSMAs) in PPHJ leads to poor flexibility, and the NFSMAs solution shows inadequate viscosity during the printing of acceptor layer. Herein, we propose a novel approach termed polymer-incorporated pseudo-planar heterojunction (PiPPHJ), wherein a small amount of polymer donor is introduced into the NFSMAs layer. Our findings demonstrate that the incorporation of polymer increases the viscosity of acceptor solution, thereby improving the blade-coating processability and overall film quality. Simultaneously, this strategy effectively modulates the vertical component distribution, resulting in more donor/acceptor interfaces and an improved power conversion efficiency of 17.26%. Furthermore, PiPPHJ-based films exhibit superior tensile properties, with a crack onset strain of 12.0%, surpassing PPHJ-based films (9.6%). Consequently, large-area (1 cm2) flexible devices achieve a considerable efficiency of 13.30% and maintain excellent mechanical flexibility with 82% of the initial efficiency after 1000 bending cycles. These findings underscore the significant potential of PiPPHJ-based OSCs in flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

The distinguishing feature of a flexible electronic device is that it maintains its function even when the shape changes repeatedly. As the degree of integration of flexible devices increases, revealing failure mechanisms and extending the lifetime of the flexible devices are getting more difficult. One of the potential damage zones is the interface of heterogeneous material components, where strain can be localized due to the mismatch of mechanical properties. In this study, we investigate the mechanically reliable interconnect design of the flexible printed circuit board (FPCB) system in which the packaging chip is integrated. When the FPCB was bent, folding occurred at the edge of the packaging chip due to the high bending rigidity compared with the plastic substrate and resulted in high strain concentration. By introducing interconnect architecture that bypassed the strain concentration area around the packaging chip, mechanical damage of the interconnects was successfully reduced. Through finite element simulation, the strain applied to the interconnect crossing the strain-concentrated region was predicted to be 2 times larger than that bypassing the strain-concentrated region, from 8.32 to 4.64%. In addition, the strain gap of these two interconnects could be increased as the Young's modulus mismatch between the packaging chip and the substrate increased. This study is expected to improve the design guidelines to mechanically reliable interconnects in highly integrated flexible electronics. [ABSTRACT FROM AUTHOR]

The hydrophilicity of carbon cloth was improved through pretreatment using an oxidation process resulting in activated carbon cloth with microscopically pronounced grooved cracks. This activated carbon cloth served as a highly hydrophilic substrate suitable for electrode material loading while also possessing attractive electrochemical properties. Polypyrrole/reduced graphene oxide (PPy/rGO) composites were subsequently polymerized and chemically reduced in situ on the pretreated carbon cloth (HCC), introducing nitrogen atoms of different valences into the composite. Contact angle and electrochemical tests demonstrate that the prepared electrode material displayed enhanced hydrophilicity and low impedance. Based on HCC/PPy/rGO, the symmetrical flexible quasi-solid supercapacitor exhibited a high energy density of 0.60 mWh cm−3 at a power density of 6.25 mW cm−3, as well as a great power density of 62.5 mW cm−3 at 0.34 mWh cm−3 and good flexibility. Moreover, three fabricated supercapacitor devices connected in series illuminated a white LED for about 4 min, demonstrating the potential use of pretreated-carbon cloth/polypyrrole/rGO materials for flexible wearable devices. [ABSTRACT FROM AUTHOR]

Advances in MEMS technology have enabled the development of smaller and more efficient electronic devices, integrating nanoscale components. Coupled with progress in flexible semiconductors, the potential applications of flexible electronics have significantly broadened. Yet, wearable and flexible electronics often face challenges related to thermal management owing to the low thermal conductivity of polymers—a crucial issue for wearables in direct contact with the skin. This study introduces an innovative approach to enhance wicking performance on flexible substrates aiming to improve thermal management. The approach involves creating intricate porous patterns on graphene structures through direct laser writing, using a CO2 laser on a polyimide substrate with specific parameters. Eight distinct laser-induced graphene (LIG) samples were produced, each with different laser powers ranging from 9 to 23 W. A surface analysis confirmed the successful transformation of polyimide into porous graphene through laser ablation. The surface properties were evaluated before and after the oxygen plasma treatment, supported by XRD and XPS results. The liquid transport capacity of the LIG samples was accurately measured using the capillary rate-of-rise method. Lower powers (9 and 11 W) exhibited slower rates of wicking velocity, ranging from 5.0 mm/s0.5 to 6.3 mm/s0.5, whereas higher powers demonstrated increased rates, reaching 9.5 to 13.6 mm/s0.5. These findings explicitly demonstrate the superior liquid delivery capability of LIG, achieving wicking velocities up to four times higher than those in relevant existing studies. [ABSTRACT FROM AUTHOR]

Environmental concerns arising from industrial growth, and in particular the accumulation of waste and toxic substances, have prompted the demand for sustainable and ecofriendly solutions. Cellulose, known for its ecological attributes, is a cost-effective and recyclable material that is suitable for replacing silicon substrates, particularly in flexible electronic devices. However, the limitations of 2D techniques, such as inkjet and screen printing, necessitate the adoption of 3D printing technologies in this domain. This study introduces a novel approach utilizing fused deposition modeling printing (FDM) to create a mulberry paper (MP)-graphene filament strain sensor. This process involves the melting and extrusion of multifunctional filaments, which requires a meticulous examination of the bonding between MP and polymers. To optimize the bonding between MP and graphene filaments, adjustments were made to the nozzle and platform temperatures, as well as the printing gap, resulting in a substantial binding strength of 3.85 N, exceeding that of conventional paper by more than 2.5-fold (1.58 N). Leveraging this impressive binding strength, the strain sensor achieved a remarkable gauge factor of approximately 648 and commendable linearity of 0.94. The practical application of the FDM-based MP-graphene filament strain sensor in a household wind speed sensing system showed promising results within a wind range of 8.9–9.4 m/s. The integration of cellulose-based MP and graphene filaments via FDM printing is a pivotal advancement in the development of eco-friendly high-performance strain sensors, offering potential solutions to environmental concerns and application in flexible electronic devices. [ABSTRACT FROM AUTHOR]

In this work, flexible silica (SiO2) aerogels were prepared, using Methyltriethoxysilane (MTES) and Dimethyldiethoxysilane (DMDES) as co-precursor, via two-step acid/base catalyzed sol–gel process and the following ambient pressure drying (APD) process, without using any surfactant. The molar ratio of MTES/DMDES and the concentration of the central silicon, influenced not only on the morphology and physical performance of the final samples, but also on the specific mechanism of the sol–gel chemistry. The results of FTIR, XPS, SEM images, stress-strain curves, etc for the final samples would illustrated these influence. And moreover, based on the similarity between the sol–gel process of siloxanes precursors and the network step polymerization of organic monomers, some basic concepts and theories in organic polymerization, such as the average functionality and Carothers equation, were adopted to discuss the reactive mode of MTES/DMDES co-precursor. Therefore, this work might be helpful for future research into functionally diverse, robust silica aerogels. Highlights: The MTES/DMDES hybrid silica aerogels were prepared without using any surfactant. A two-step acid/base catalyzed sol–gel process was applied to control the phase separation of MTES/DMDES co-precursor in polar solvent Ethanol. Some basic concepts and theories in organic polymerization, such as the average functionality and Carothers equation, were adopted to discuss the reactive mode of MTES/DMDES co-precursor. The MTES/DMDES hybrid silica aerogels endured ambient pressure drying process, and still displayed favourable mechanical property. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of semirigid ureteroscopy and tamsulosin therapy as dilatation methods before flexible ureteroscopy advancement to the renal collecting system. Patients and methods: This prospective study included patients with renal stones less than 2 cm who underwent retrograde flexible ureteroscopy and laser lithotripsy. The patients were randomized into two groups: group A patients were given a placebo for 1 week before flexible ureteroscopy, and group B patients were administered 0.4 mg of tamsulosin once daily for 1 week before surgery and underwent active dilatation using semirigid ureteroscopy before flexible ureteroscopy. The ability of the flexible ureteroscope to reach the collecting system in both groups during the same operative session was assessed. Operative outcomes and complications were collected and analyzed in both groups. Results: A total of 170 patients were included in our study, with each group comprising 85 patients. In group B, the flexible ureteroscope successfully accessed the kidney in 61 patients, while in group A, the flexible ureteroscope was successful only in 28 cases (71.4% versus 32.9%). In group A, 33 (38.8%) patients had lower urinary tract symptoms compared to 17 (20.2%) patients in group B (P = 0.013). Conclusion: Using tamsulosin therapy and semirigid ureteroscopy as dilatation methods before flexible ureteroscopy increased the success of primary flexible ureteroscopy advancement to renal collecting system. [ABSTRACT FROM AUTHOR]

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Polyvinylidene fluoride (PVDF) is one of the established thermoplastics for bio-sensing applications, and several studies have been reported on the use of this material as tactile sensors. But hitherto little has been reported on 3D printing of primary (1°) recycled PVDF-based sensors in lower C-band applications (for miniaturization, flexibility, and wearability features). This study reports the 3D printing of 1° recycled PVDF-based flexible and wearable miniaturized sensors for lower C-band applications. The 1° recycled PVDF substrate (for the sensor) was 3D printed by using fused filament fabrication. The ring resonator technique and transmission line method were used to ascertain the dielectric constant (3.3) and loss tangent (~ 0.003) of the substrate. The prepared sensor has a return loss of ≈ − 20 dB at 4.1 GHz and shows good conformability for bending up to 70 mm replicating the human body part. The specific absorption rate was recorded to be 0.6W/kg. Further, the negligible variation in S-parameter during the in vitro testing validates the adopted method and supports the use of miniaturized sensors for lower C-band applications. [ABSTRACT FROM AUTHOR]

Proteins have great potential as renewable materials, and the valorization of protein-rich byproducts in food production and biorefineries can additionally increase the environmental and economical sustainability of these sectors. Proteins are polyamides that are characterized by their extensive intra- and intermolecular interactions. They are stiff and brittle, and have high softening temperatures in the absence of solvents or plasticizers. In this prospective, strategies that convert proteins into mechanically robust and processable materials are summarized. Structure–property relationships are discussed alongside protein modification and material design strategies, and the challenges and outlook for protein-based materials are presented. [ABSTRACT FROM AUTHOR]

A high-performance sandwich-structure low-voltage ionic electroactive actuator was fabricated by self-standing ion-exchange Nafion membranes and conductive PEDOT:PSS electrodes by hot-pressing. The actuation properties of the hot-pressed PEDOT:PSS/Nafion soft actuator were examined in a function of alternating sine-wave voltages (0.25–3 V) and frequencies (0.1–0.5 Hz), showing a large bending displacement of 5.7 mm with four sets of measurements without degradation, a long-term cyclic stability of 98% up to 300 cycles (1.0 V, 0.1 Hz), and a high bending strain of 0.25% with low applied voltages of 0.25 to 3 V. Additionally, the thickness had an impact on the degree of actuation displacement. Moreover, potential actuator applications including microgrippers, microsorters, and bioinspired fingers were introduced, opening up more possibilities for the next-generation advancement of actuators in biosensor microrobots and biomedical microdevices. [ABSTRACT FROM AUTHOR]

To enhance the flexibility of electrostatically spun PAN-based carbon nanofiber films for wearable textile applications, this study aimed to prepare PAN nanofiber films by incorporating the 1173 photoinitiator. Subsequently, UV irradiation, pre-oxidation treatment, and high-temperature carbonization processes were employed to develop PAN nanofiber films with improved mechanical properties. The results indicated that UV irradiation treatment significantly promoted the degree of pre-oxidation reaction in PAN nanofiber membranes. Thermal performance characterization demonstrated that UV irradiation reduced the initiation temperature of the cyclization reaction and mitigated the concentration of exothermic phenomena. Raman spectra analysis revealed increased graphitization in the carbon nanofiber film following UV irradiation, as evidenced by a decrease in the ID/IG value to 0.908. This suggests that UV irradiation facilitated stable carbonization and enhanced the graphitization of the carbon fiber within PAN nanofiber films. Moreover, the stress–strain curve indicated that the breaking strength of the nanofiber film reached 1.45 MPa after 20 min of UV irradiation while maintaining an elongation at a break of 3.5%, demonstrating its remarkable strength and toughness. The resulting flexible carbon nanofiber film holds great potential for medical textiles, filtration membranes, flexible capacitors, and more applications. [ABSTRACT FROM AUTHOR]

Converting agricultural residues into valuable materials has been recently a hot trend because biomass is a cellulose-rich source to efficiently manufacture cellulose-based materials. In this study, sponge-like carbon aerogels from biomass-derived cellulose are successfully fabricated using a rapid, simple, and cost-effective method without using harmful and toxic ingredients. The synthesized carbon aerogels are promising candidates for oil spill removal due to their hydrophobicity and oleophilicity. The aerogels producing from pineapple leaf fibers with the usage of polyamidoamine epichlorohydrin (PAE) as a cross-linker are pyrolyzed at 750 °C to form an ultra-light (density of 0.0088 g cm−3), super porous (99.68%) and flexible carbon aerogels. The as-fabricated aerogels show a fast adsorption rate (less than 30 s) and preeminent adsorption capability to various types of oil, in particular for the pump oil, at approx. 130 g g−1. Carbon aerogels with 5 wt% of PAE compared to dry microfibrilled cellulose (MFC) weight exhibit the highest capacity of oil adsorption by the value of 113 g g−1 for olive oil. A plinth freezing by a copper block results in vertically-aligned aerogels having oil adsorption capacity increased by 25% compared with the non-directional ones. Additionally, the adsorption capacity of the material maintains 75% of the initial value after 7 adsorption–desorption cycles. Therefore, our high-performance aerogels from affordable resources show great potential in treating oil spills effectively. [ABSTRACT FROM AUTHOR]

Nowadays, there are many different industrial processes in which people spend several hours performing tedious and repetitive tasks. Furthermore, most of these processes involve the manipulation of dangerous materials or machinery, such as the toy manufacturing, where people handle ovens with high temperatures and make weary physical effort for a long period of time during the process. In this work, it is presented an automatic and innovative collaborative robotic system that is able to deal with the demoulding task during the manufacturing process of toy dolls. The intelligent robotic system is composed by an UR10e robot with a RealSense RGB-D camera integrated which detects the pieces in the mould using a developed vision-based algorithm and extracts them by means of a custom gripper located and the end of the robot. We introduce a pipeline to perform the demoulding task of different plastic pieces relying in the use of this intelligent robotic system. Finally, to validate this approach, the automatic method has been successfully implemented in a real toy factory providing a novel approach in this traditional manufacturing process. The paper describes the robotic system performance using different forces and velocities, obtaining a success rate of more than 90% in the experimental results. [ABSTRACT FROM AUTHOR]

In order to study the dynamic position accuracy of bottom dead point (BDP) for multilink high-speed precision presses (MHSPPs), it's essential to develop a dynamic model of planar multilink mechanism. Traditional dynamic error models (DEMs) always neglect the thermal effect of angular contact ball bearing (ACBB), which reduces the prediction accuracy of DEM for multilink transmission mechanisms. To overcome the shortcomings of the previous models, a new contact model of revolute clearance joint considering thermal expansion effect is proposed in this paper. Then, a thermal network model (TNM) of ACBB lubricated by grease is built and the stiffness of ACBB considering the thermal expansion effect is derived. On this basis, an improved DEM of planar flexible multilink mechanism with clearance considering the thermal expansion effect of ACBB is developed. And the influence of crankshaft speed, contact angle of ACBB and clearance size on the position error of slider's BDP based on the improved DEM is analyzed. Compared to the simulation from traditional models, the simulated slider's BDP position error from the improved DEM agrees better with experimental data, which verifies the correctness of the proposed model. It's demonstrated that the punching force and thermally induced variable stiffness of bearing lead to a significant increase in the slider's BDP position error, which reduces the machining precision of MHSPP. Moreover, a novel compensation algorithm based on the improved DEM with online modification is proposed. Test results show that the root mean square (RMS) and maximum absolute values of the slider's BDP position error after compensation under no load condition are reduced by 98.06% and 96.20%, respectively, and can be reduced by 98.11% and 96.36%, respectively. [ABSTRACT FROM AUTHOR]

Laser ablation is considered a promising alternative to conventional mask fabrication methods for flexible sensors. For the efficient and high-quality patterning of circuit and electrode geometries, numerous process parameters must be optimized to obtain the necessary laser fluence and pulse overlap that allow for precise, clean cuts in thin, heat-sensitive materials. This study investigates the ability to achieve target cut widths and depths during the pulsed UV laser ablation of NiCr films at various laser powers (0.2 to 1 W), laser scan speeds (0.1 to 0.6 m/s), and pulse frequencies (30 to 100 kHz). Significant variation is observed in the depth, width, and quality of ablated microchannels formed at similar laser fluence and pulse overlap, with the typical fluence-based model giving poor predictions (R2 = 0.37 to 0.57). To address this, an improved fluence-based model that incorporates the effect of a moving laser source using a physics-based approach is proposed (R2 = 0.62 to 0.82). This model is then used to select process parameters for the fabrication of electrically insulated features (> 5 µm cut depth) with the smallest channel width possible (13.7 µm). This process parameter selection approach has the ability to shorten development times and facilitate the fabrication of custom flexible sensors. [ABSTRACT FROM AUTHOR]

Purpose: A single-use digital flexible ureteroscope (fURS) has become a cost-effective alternative option to reusable fURS. The requirement of large-diameter access sheath for passage of 9.5 Fr single-use fURS has not always achieved in the first attempt in all cases leading to stage stone clearance. Recently, two slimmest single-use digital disposable fURSs have been introduced by Bioradmedisys™ and Pusen™ to mitigate the accessibility problem, without or with small size access sheath. Primary objective was to compare in vivo performance and surgical outcomes with two single-use fURS: 7.5Fr Indoscope (Bioradmedisys™, Pune, India) and 7.5Fr Uscope PU3033A (Pusen, Zhuhai, China). Methods: 60 patients undergoing Retrograde Intrarenal Surgery (RIRS) with < 2 cm renal stones were prospectively randomized into: Group A (30 patients) for Indoscope and Group B (30 patients) for Uscope PU3033A. Pre-operative, intra-operative, and post-operative parameters were evaluated. In vivo visibility and maneuverability were rated on 5-point Likert scale by the operating surgeon. At one-month stone clearance was assessed with ultrasound and X-ray KUB. Data were analyzed using SPSS 23.0. Results: Patient demographics and stone characteristics were comparable in both groups. Indoscope had significantly higher visibility (p < 0.05) than Uscope; however, the maneuverability scores were comparable between both the groups (p > 0.05). 28 patients in group A and 26 patients in group B achieved complete stone clearance (p = 0.38). Scope failure was observed in 1 case of group B (p = 0.31). Conclusion: We conclude that 7.5Fr Indoscope has better vision than 7.5Fr Uscope and the rest of in vivo performances were comparable with similar outcomes and complications among both scopes. [ABSTRACT FROM AUTHOR]

This work demonstrates three reliable methods to connect neural stimulation, recording, and modulating technologies to thin film softening bioelectronic devices. These softening devices are manufactured on thiol-based shape memory polymers (SMPs) with photolithographic techniques including gold traces and high charge injection capacity titanium nitride (TiN) electrodes. The charge storage capacity and electrochemical performance of the fabricated devices were compared when interconnected using three different interface methods: surface mounting, ultra-thin chips (UTC), and through-hole substrate etching. Cathodal charge storage capacities above 8 mC/cm2 are demonstrated while maintaining average impedances less than 1 kΩ at 1 kHz for each interconnect technique. [ABSTRACT FROM AUTHOR]

Extensively studied transfer methods for producing high-performance flexible micro-light-emitting diodes (µLEDs) have limitations like high process cost and size constraints. Herein, we report a novel inorganic-based laser lift-off (ILLO) process, in which a new BaTiO3 (BTO) sacrificial layer is used to fabricate flexible thin-film µLEDs. The process, associated laser conditions, and carrier substrate types were optimized using theoretical simulations and experiments. The BTO sacrificial layer was successfully applied to the ILLO process via laser–material interactions, as verified by material analyses. Vertically structured flexible µLEDs were realized using BTO-based delamination, demonstrating the method's applicability to next-generation electronics. [ABSTRACT FROM AUTHOR]

Computer vision techniques are real-time, immersive, and perceptual human-computer interaction technology. Excellent display effect, dynamic surface flexibility, and safe bio-adhesion are essential for various human–computer interaction applications, such as metaverse interfaces, skin-like sensors, and optoelectronic medical devices. However, realizing the flexible matching of inorganic optoelectronic devices and organisms remains a grand challenge for current display technologies. Here, we proposed a novel strategy by combining the optoelectronic advantages of inorganic micro light emitting diode (micro-LED) display and the extraordinary mechanical/biological compatibility of organic materials to overcome this challenge. A highly elastic (greater than 2000% strain), highly transparent (94% visible light transmittance), biocompatible conductive hydrogel composite electrode layer was fabricated. For the first time, we realized the on-chip electrical interconnection of 4900 LED units to form a blue-green light display patch with high resolution (264 PPI), low power consumption (4.4 mW) and adaptive surface attachment. This work demonstrates an integrated scheme and potential applications of flexible high-resolution microdisplays, such as wearable full-color micro-LED smart curved display devices and conformable biomedical monitoring systems. [ABSTRACT FROM AUTHOR]

Given the limited data on the predictive factors of residual kidney stone size after flexible ureteroscopy (fURS), this study aims to investigate the variables affecting residual stone size. The medical records of 642 patients without complications being treated for kidney stones with fURS between July 2014 and May 2022 were reviewed retrospectively, and the information of the 170 patients in whom residual stones were found was recorded. In addition to patient-specific factors and stone characteristics, length of postoperative hospital stay, postoperative fever, and preoperative antiaggregant use were evaluated. Of the 170 patients ultimately included in the study. The mean age was 51.56 (± 14.70). The mean stone size was 14.01 mm (± 5.75), the mean residual stone size was 7.04 mm (± 2.51), and the mean stone density was 829 Hounsfield units (± 395.06). The mean infundibulopelvic angle (IPA) was 49.37º (± 15.37), and 41.2% of the stones were non-opaque. The mean parenchymal thickness was 22.88 mm (± 5.55). 34 patients were on antiaggregant therapy. Preoperative stone size increases in stone density and decreases in IPA were found to be correlated with increase residual stone size (p < 0.001, p < 0.001, and p < 0.001, respectively). In addition, larger residual stones were observed after the fURS procedure in patients using anticoagulants and those without hydronephrosis (p = 0.02 and p = 0.016, respectively). Use of reliable predictive factors to forecast residual stone size after fURS may help to inform those treated and enable urologists to design rational surgical strategies. [ABSTRACT FROM AUTHOR]

A multi-client functional encryption (MCFE ) scheme [Goldwasser–Gordon–Goyal 2014] for set intersection is a cryptographic primitive that enables an evaluator to learn the intersection from all sets of a predetermined number of clients, without need to learn the plaintext set of each individual client. Using these schemes, it is impossible to compute the set intersections from arbitrary subsets of clients, and thus, this constraint limits the range of its applications. To provide such a possibility, we redefine the syntax and security notions of MCFE schemes, and introduce flexible multi-client functional encryption (FMCFE ) schemes. We extend the aIND security of MCFE schemes to aIND security of FMCFE schemes in a straightforward way. For a universal set with polynomial size in security parameter, we propose an FMCFE construction for achieving aIND security. Our construction computes set intersection for n clients that each holds a set with m elements, in time O (n m) . We also prove the security of our construction under DDH1 that it is a variant of the symmetric external Diffie–Hellman (SXDH) assumption. [ABSTRACT FROM AUTHOR]

This article proposes a flexible optical radiation absorber based on a modified Huguenot cross-shaped nanostructure. The suggested plasmonic metamaterial flexible absorber (PMFA) structure consists of three layers noted as a metallic ground plane, an insulating separator surface, and a metallic upper layer. A ground plane of thickness 7 nm is made up of Nickel (Ni) with the full ground geometry, a Glass of 12 nm is used as an insulating separator, and the 7 nm top metallic layer of Ni is used to form the proposed PMFA. This unit cell has a periodicity of 80 nm only. The intrinsic absorption of Glass coupled with the surface plasma resonance provides a mean absorbance of more than 97% between 190 and 1350 THz. The absorption is similar for all polarization angles among TE and TM modes. The flexibility of the proposed PMFA is also studied by bending the unit cell structure. The mean absorption remains almost the same as the flat structure in the TM mode, and in the TE mode, it is 92%. Owing to its wide functioning bandwidth, flexibility, oblique incident and polarization reliability, ultra-compact cross-sectional-sectional area, and incorporation of an inexpensive and high-temperature-resistant metal (Ni), this PMFA is an appealing candidate for electromagnetic shielding, stealth technology in avionics, solar energy harvesting and IoT applications. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW) is an ambient temperature additive manufacturing (AM) method that accommodates many possible ink materials. Here, we demonstrate using a moisture-curable commercially available polyurethane (PU) sealant as an alternative ink for DIW. We discussed the fundamentals of PU chemistry and determined the best 3D printing parameters. Studies on rheological, thermogravimetric, spectroscopic characterization, and initial finite element analyses (FEA) showed properties expected from a performance sealant with high elongation and low modulus of a 3D-printed object. This affirms the flexibility of the DIW technique as an accessible AM method amenable for future materials development from commercial model formulations. [ABSTRACT FROM AUTHOR]

Today, the aerospace industry is improving competitive systems because of potential development in new aircraft demand, which are to be supplied on a unique manufacturing system while diminishing components changeover time and developing the total quality management program of the manufacturing system. It should be successfully using special jigs and fixtures in the production system. A specialized modular fixture includes standard components that can be applied to success flexibly and rapidly respond to engineering design characteristics. In our study, the purpose of the concept is to design and analyze flexible modular fixtures for aircraft fuselage panel assembly for the aerospace industry. The developed modular fixturing system can be easily adapted to other sectors such as automobiles or machinery due to its flexibility. [ABSTRACT FROM AUTHOR]

Among many aqueous batteries, flexible zinc-ion (Zn-ion) battery becomes the focus owing to the merits of low cost, non-toxicity, and safety. Here, a Zn dendrite-suppressible hydrogel electrolyte with both flexible and self-healing properties is developed via photoinitiated polymerization. The cross-linked structure of the polyacrylamide-N,N′-methylenebisacrylamide (PAM-MBA)-Zn/Mn hydrogel endows an enlarged chemical stable window, high ionic conductivity, and low polarization potential. After cycling at the current density of 0.5 mA·cm−2 for 250 h, Zn∥Zn symmetrical cell based on PAM-MBA-Zn/Mn electrolyte delivers a low polarization of 40 mV. The suppressed dendrite growth is ascribed to the uniform Zn deposition/stripping on anode. The galvanostatic intermittent titration technique curves display that the Zn-ion battery constructed by the PAM-MBA-Zn/Mn hydrogel electrolyte, free-standing FeVO4/carbon cloth cathode, and Zn nanosheets/carbon cloth anode presents low reaction resistance and fast diffusion coefficient, indicating good endurance of cycling at high current densities. The battery with PAM-MBA-Zn/Mn hydrogel electrolyte presents a good flexible and self-healing performance. After bending 0°, 60°, 90°, and 180° for 30 times, batteries deliver stable capacities. Even cutting into ten pieces, the battery could self-heal and display a potential retention of 93.7% compared to the fresh cell. A good rate-performance is also achieved. After cutting/healing three times during cycling, capacity recovers well compared to the first-time cutting/healing. Moreover, the battery exhibits good flexibility using in an electric watch, indicating a promising potential for wearable electronics. [ABSTRACT FROM AUTHOR]

For the large amount of waste heat wasted in daily life and industrial production, we propose a new type of flexible thermoelectric generators (F-TEGs) which can be used as a large area bionic skin to achieve energy harvesting of thermal energy. With reference to biological structures such as pinecone, succulent, and feathers, we have designed and fabricated a biomimetic flexible TEG that can be applied in a wide temperature range which has the highest temperature energy harvesting capability currently. The laminated free structure of the bionic F-TEG dramatically increases the efficiency and density of energy harvesting. The F-TEGs (single TEG only 101.2 mg in weight), without an additional heat sink, demonstrates the highest output voltage density of 286.1 mV/cm2 and the maximum power density is 66.5 mW/m2 at a temperature difference of nearly 1000 °C. The flexible characteristics of F-TEGs make it possible to collect the diffused thermal energy by flexible attachment to the outer walls of high-temperature pipes and vessels of different diameters and shapes. This work shows a new design and application concept for flexible thermal energy collectors, which fills the gap of flexible energy harvesting in high-temperature environment. [ABSTRACT FROM AUTHOR]

Solid-state lithium batteries using composite polymer electrolytes (CPEs) have attracted much attention owing to their higher safety compared to liquid electrolytes and flexibility compared to ceramic electrolytes. However, their unsatisfactory lithium-ion conductivity still limits their development. Herein, a high ion conductive CPE with multiple continuous lithium pathways is designed. This new electrolyte consists of poly(vinylidene fluorideco-hexafluoropropylene) (PVDF-HFP) and lithiated X type zeolite (Li-X), which possesses a high ionic conductivity (1.98 × 10−4 S/cm), high lithium transference number (t Li + = 0.55) , wide electrochemical window (4.7 V), and excellent stability against the lithium anode. Density functional theory (DFT) calculation confirms that the Lewis acid sites in zeolite can graft with N,N-dimethylformamide (DMF) and PVDF-HFP chains, resulting in decreased crystallinity of polymer and providing rapid Li+ transmission channels. When used in a full cell, the solid Li∣Li-X-3%∣LiFePO4 cell displays excellent cycling stability and rate performance at room temperature and 60 °C. Furthermore, pouch cells with the Li-X-3% electrolyte exhibit brilliant safety under extreme conditions, such as folding and cutting. Thus, this proposed zeolite-PVDF-HFP CPE represents a promising potential in the application of making a safer, higher performing, and flexible solid-state lithium battery. [ABSTRACT FROM AUTHOR]

In this article, a low-profile quad-port wideband and multiband printed conformal antenna for 4G/5G WLAN/Wi-Fi 6E applications is presented. The designed antenna is printed on a 0.5 mm thick transparent polymide substrate with dimensions of 112.8 × 112.8 mm2. Over a 10 dB impedance bandwidth, the slotted ground plane antenna can operate in the following spectrums: 2.2–2.6 GHz (Bluetooth, ISM band, Wi-Fi), 3–5.59 GHz (LTE band 42, New radio bands 77, 78, and 79), and 5.8–7.1 GHz (5G WLAN, Vehicular Band, Wi-Fi 6E band). Therefore, the antenna presented in this research has versatile operation, almost covering existing and upcoming frequency bands for 4G and 5G applications, respectively. The proposed conformal antenna also provides superior performance in terms of isolation—better than 20 dB—even after antenna elements are kept with a minimum distance between them. Because of such isolation improvements, it is possible to achieve a radiation efficiency of up to 93 percent with an overall gain of around 4.8 dBi over the desired operating band. Further, MIMO characteristics including channel capacity, Envelope Correlation Co-Efficient, Channel Capacity Loss and Diversity gain have been calculated to validate the MIMO performance of the proposed antenna. More studies have shown that the suggested antenna works well enough for both multi-band and wide-band applications. [ABSTRACT FROM AUTHOR]

A broad-band, conformal, highly efficient antenna for bio-medical and 5G applications is presented in this paper to serve the communities of smart cities. Flexibility of an antenna is achieved by printing radiating elements (both antenna and ground plane) on 0.6-mm-thick jeans fabric whose dielectric constant (ξr) and tangential loss (δ) are 1.78 and 0.035, respectively. The designed antenna spans the spectrum from 2 to 4 GHz over a 10 dB scale for reflection coefficient (66.67% impedance bandwidth). Wide-band operation of the proposed antenna is obtained by making a square slot in the ground plane along with a circular radiator that is printed above the substrate. The proposed body-worn antenna is manufactured, and typical parameters are measured. To validate the real-time performance of the antenna, conformability analysis has been made, thereby assessing the robustness of the proposed system. The antenna achieves overall efficiency up to 90% over the operating spectrum with a substantial gain of around 3.35 dBi. The antenna exhibits a minimum Specific Absorption Rate (SAR) lower than 0.7 W/Kg for both 1 g and 10 g human tissues. A detailed state-of-the-art comparison has been provided to demonstrate how it differs from other antennas in the literature. [ABSTRACT FROM AUTHOR]

Si-based optical position-sensitive detectors (PSDs) have stimulated the interest of researchers due to their wide range of practical applications. However, due to the rigidity and fragility of Si crystals, the applications of flexible PSDs have been limited. Therefore, we presented a flexible broadband PSD based on a WS2/Si heterostructure for the first time. A scalable sputtering method was used to deposit WS2 thin films onto the etched ultrathin crystalline Si surface. The fabricated flexible PSD device has a broad spectral response in the wavelength range of 450–1350 nm, with a high position sensitivity of ∼539.8 mV·mm−1 and a fast response of 2.3 µs, thanks to the strong light absorption, the built-in electrical field at the WS2/Si interface, and facilitated transport. Furthermore, mechanical-bending tests revealed that after 200 mechanical-bending cycles, the WS2/Si PSDs have excellent mechanical flexibility, stability, and durability, demonstrating the great potential in wearable PSDs with competitive performance. [ABSTRACT FROM AUTHOR]

Next-generation optoelectronics should possess lightweight and flexible characteristics, thus conforming to various types of surfaces or human skins for portable and wearable applications. Flexible photodetectors as fundamental devices have been receiving increasing attention owing to their potential applications in artificial intelligence, aerospace industry, and wise information technology of 120, among which perovskite is a promising candidate as the light-harvesting material for its outstanding optical and electrical properties, remarkable mechanical flexibility, low-cost and low-temperature processing methods. To date, most of the reports have demonstrated the fabrication methods of the perovskite materials, materials engineering, applications in solar cells, light-emitting diodes, lasers, and photodetectors, strategies for device performance enhancement, few can be seen with a focus on the processing strategies of perovskite-based flexible photodetectors, which we will give a comprehensive summary, herein. To begin with, a brief introduction to the fabrication methods of perovskite (solution and vapor-based methods), device configurations (photovoltaic, photoconductor, and phototransistor), and performance parameters of the perovskite-based photodetectors are first arranged. Emphatically, processing strategies for photodetectors are presented following, including flexible substrates (i.e., polymer, carbon cloth, fiber, paper, etc.), soft electrodes (i.e., metal-based conductive networks, carbon-based conductive materials, and two-dimensional (2D) conductive materials, etc.), conformal encapsulation (single-layer and multilayer stacked encapsulation), low-dimensional perovskites (0D, 1D, and 2D nanostructures), and elaborate device structures. Typical applications of perovskite-based flexible photodetectors such as optical communication, image sensing, and health monitoring are further exhibited to learn the flexible photodetectors on a deeper level. Challenges and future research directions of perovskite-based flexible photodetectors are proposed in the end. The purpose of this review is not only to shed light on the basic design principle of flexible photodetectors, but also to serve as the roadmap for further developments of flexible photodetectors and exploring their applications in the fields of industrial manufacturing, human life, and health care. [ABSTRACT FROM AUTHOR]