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The next‐generation bionics and, more specifically, wearable and implantable bioelectronics require wireless, battery‐free, long‐term operation and seamless bio‐integration. Design considerations, materials choice, and implementation of efficient architectures have become crucial for the fabrication and deployment of wireless devices, especially if they are flexible or soft. Wireless power and data transfer represent key elements for the development of robust, efficient, and reliable systems for health monitoring, advanced disease diagnosis and treatment, personalized medicine. Here, the recent advances in materials and technologies used for wireless energy sourcing and telemetry in bio‐integrated flexible bionic and bioelectronic systems are reviewed. The study tackles different challenges related to mechanical compliance, low thickness, small footprint, biocompatibility, biodegradability, and in vivo implementation. The work also delves into the main figures of merit that are mostly adopted to quantify the wireless power/data transfer performances. Lastly, the pivotal applications of wearable and implantable wireless bionics/bioelectronics are summarized, such as electrical stimulation/recording, real‐time monitoring of physiological parameters, light delivery trough optical interfaces, electromechanical stimulation via ultrasounds, highlighting their potential for future implementation and the challenges related to their commercialization. [ABSTRACT FROM AUTHOR]

Flexible photoelectrochemical (PEC) based sensors have been extensively investigated for noninvasive healthcare monitoring. However, known electrode materials struggle to combine technologically relevant metrics of high sensitivity and flexibility due to their low electrical conductivity and fragile mechanical properties. Herein, a flexible PEC‐based sensor for dopamine (DA) detection is presented by integrating highly conductive and flexible MXene between CdS quantum dots and g‐C3N4 with suitable energy level matching. Theoretical calculations reveal that the interfaces of constructed PEC electrodes with enhanced electronic conductivity derived from MXene not only improve the electron transfer kinetics, but form built‐in electric fields at the interfaces, facilitating the separation efficiency of electron–hole pairs. As a result, the as‐prepared sensors display the combined advantages of a wide detection range (1 nM–0.1 mM), low detection limit (0.48 nM), high stability, selectivity, and repeatability for DA detection. Building on these metrics, a scalable screen‐printing method is further developed for integrating the sensors on flexible platforms. These all‐integrated PEC‐based sensors exhibit stable photocurrent signals under different bending angles and bending cycles. Therefore, this work demonstrates the scalable development of flexible PEC‐based sensors for the sensitive detection of DA and holds promise for the future development of noninvasive healthcare monitoring. [ABSTRACT FROM AUTHOR]

Inorganic semiconductor gas sensors, being widely utilized in gas‐sensing applications, face significant challenges in attaining mechanical flexibility and humidity resistance in wearable sensing fields. Herein, a highly flexible, breathable, and hydrophobic all‐inorganic self‐supporting nanofiber (NF) gas sensor is developed using electrospinning combined with thermal sulfidation approach. This innovative sensor features a bilayer configuration, with an amorphous SiO2 nanofiber substrate layer and an interwoven SiO2 and SnO2–SnS2 nanofiber active layer. The relatively low elastic modulus of the amorphous SiO2 nanofibers, combined with the three‐dimensional network interwoven structure, endow the SnO2–SnS2–SiO2/SiO2 sensor with superior mechanical flexibility. The sensor exhibits excellent sensitivity, selectivity, moisture resistance, and cycling stability (>10 000 cycles at 140° bending) to both high and low concentration NO2. Notably, an excellent flexible detecting capability of the sensor to NO2, an asthma‐related biomarker, is demonstrated at ultralow concentrations (≈25 ppb) in simulated exhaled breath environments. The enhanced moisture resistance is attributed to the effective inhibition of hydrogen bond formation from H2O molecules by the Sn─S bonds formed through sulfidation of SnO2 nanofibers. This work represents a substantial advancement in the universal fabrication of flexible, breathable and moisture‐resistant inorganic semiconductor sensors for wearable breath sensing applications. [ABSTRACT FROM AUTHOR]

Background: We aim to describe our experience with bronchoscopy to diagnose and relieve tracheobronchial obstruction in anticipation of decannulation in children on extracorporeal membrane oxygenation (ECMO) support. Methods: A retrospective cohort study of children on ECMO between 1/2018 and 12/2022. Results: A total of 107 children required ECMO support during the study period for cardiac (n = 48, 45%), pulmonary (n = 38, 36%), or cardiopulmonary dysfunction (n = 21, 20%). Thirty‐seven (35%) patients underwent 99 bronchoscopies while on ECMO. Most (76%, n = 75) experienced no improvement or worsening of chest radiography 24 hours following bronchoscopy. Clinical improvement in tidal volumes 48 hours after the first bronchoscopy was noted in 13/25 patients with available data (p = 0.05). Adverse events were seen in 18 (49%) patients who underwent bronchoscopy, including pneumothorax (n = 8, 22%), pneumonia (n = 7, 19%), pulmonary hemorrhage (n = 6, 16%), and sepsis (n = 5, 14%). ECMO courses were longer (25.4 ± 37.2 vs 6.1 ± 8.8 days, p < 0.0001) and more likely to be complicated by pneumonia (p = 0.0004) and sepsis (p = 0.047) in patients who underwent bronchoscopy compared with those who did not. Adverse events following bronchoscopy were associated with the number of bronchoscopies (p = 0.0003) and the presence of obstructive materials but not with the type of bronchoscopy or indication for ECMO. Mortality rates were similar between patients who underwent bronchoscopy and those who did not. Conclusion: Children requiring bronchoscopy represent a subset of the sickest children on ECMO. Bronchoscopy may provide benefit in children with persistent cardiopulmonary failure who could not otherwise be decannulated. Adverse events are associated with the number of bronchoscopies and the presence of obstructive material. Level of Evidence: 4 Laryngoscope, 134:4134–4140, 2024 [ABSTRACT FROM AUTHOR]

The manifestation of mechanical phenomena in quantum materials at the macroscopic level is intricately linked to pronounced electron‐electron interactions within their lattices, a relationship that becomes especially evident in low‐dimensional materials. Violet phosphorous (VP), a nascent 2D material distinguished by its unique vertically aligned tubular structures, has garnered considerable attention owing to its layer‐dependent electronic bandgap, exceptional carrier mobility, and robust air stability. Herein, a comprehensive exploration of the phonon modes exhibited by few‐layer VP through an integrated experimental‐theoretical approach, focusing on the modulation of their Raman response under the uniaxial strain along a‐axis, b‐axis, and tube direction, respectively, is undertaken. Density functional theory calculations highlight when strain is applied along the a‐ or b‐axis direction, the strain is predominantly mitigated through tube rotational adaptations instead of the change of bond length and bond angle, culminating in a pronounced anisotropic Raman response. Moreover, the strain engineering can effectively optimize the photoelectric response performance of VP, including increase the responsivity ≈2500% and elevate the anisotropic ratio from 2.26 to 3.38. This investigation not only confirms the superior stretchability and impact resistance properties of cross‐structured VP but also establishes the groundwork for exploring the strain‐induced anisotropic optoelectric properties to VP. [ABSTRACT FROM AUTHOR]

Molecular sieving is an ideal separation mechanism, but controlling pore size, restricting framework flexibility, and avoiding strong adsorption are all very challenging. Here, we report a flexible adsorbent showing molecular sieving at ambient temperature and high pressure, even under high humidity. While typical guest‐induced transformations are observed, a high transition pressure of 16.6 atm is observed for C2H4 at 298 K because of very weak C2H4 adsorption (~16 kJ mol−1). Also, C2H6 is completely excluded below the pore‐opening pressure of 7.7 atm, giving single‐component selectivity of ca. 300. Quantitative high‐pressure column breakthrough experiments using 1 : 1 C2H4/C2H6 mixtures at 10 atm as input confirm molecular sieving with C2H4 adsorption of 0.73 mmol g−1 or 32 cm3(STP) cm−3 and negligible C2H6 adsorption of 0.001(2) mmol g−1, and the adsorbent can be completely regenerated by inert gas purging. Furthermore, it is highly hydrophobic with negligible water adsorption, and the C2H4/C2H6 separation performance is unaffected at high humidity. [ABSTRACT FROM AUTHOR]

Transparent materials widely used in applications such as eyewear, solar cells, and optical devices, often suffer from environmental challenges including fogging, surface contamination, and mechanical deformation. However, a universal strategy that resolves all these issues in a single platform remains to be resolved. Herein, a monolithic micropillar structure based on polydimethylsiloxane (PDMS) elastomer is prepared followed by subsequent assembly of hydrogel micropatterns in between the micropillar array using inkjet printing to achieve flexible wet‐style superhydrophobic antifogging tapes that are applicable to various transparent materials and curvatures. The monolithic micropillar structure with low‐surface‐energy characteristics facilitates easy removal of surface contaminants by rinsing with water while granting mechanical durability. In addition, micropatterning of hydrogels via inkjet printing not only enables to maintain optical transparency in a fogging environment but also makes the fabrication procedure more scalable. Furthermore, the strong adhesion between the hydrogel and the elastomer is shown to provide enhanced stability under repeated stretching cycles and long‐term exposure to water while the presence of a loosely cross‐linked PDMS at the bottom of the tape made it applicable to a wide range of transparent substrates without using additional adhesives. [ABSTRACT FROM AUTHOR]

In the rapidly evolving Metaverse, enhancing user immersion through clear, lifelike, and ergonomic near‐eye displays is crucial. However, existing rigid near‐eye displays encounter challenges such as insufficient resolution, limited adaptability, and suboptimal visual experiences. To address these issues, a strategic shift is proposed to flexible ultrahigh‐resolution (FUR) displays, which combine ultrahigh resolution with the ability to conform to individual eye curvature for a more realistic field of view. FUR quantum dot light‐emitting diodes (FUR‐QLEDs) featuring 9072 pixels per inch (PPI), a maximum external quantum efficiency (EQE) of 15.7%, and peak brightness of 15 163 cd m−2 are achieved through the integration of nanoimprinting and surface modification technologies. The degradation mechanism of FUR‐QLEDs under bending fatigue tests is investigated, identifying the high elastic modulus of the insulating patterned film as the primary cause through theoretical analysis, simulation, and experimental characterizations. Optimizing the elastic modulus of the patterned film enabled to maintain 91% of its initial brightness after 400 bending cycles, demonstrating exceptional bending stability and durability of FUR‐QLEDs. [ABSTRACT FROM AUTHOR]

Human–machine interactions (HMIs) have penetrated into various academic and industrial fields, such as robotics, virtual reality, and wearable electronics. However, the practical application of most human–machine interfaces faces notable obstacles due to their complex structure and materials, high power consumption, limited effective skin adhesion, and high cost. Herein, we report a self-powered, skin adhesive, and flexible human–machine interface based on a triboelectric nanogenerator (SSFHMI). Characterized by its simple structure and low cost, the SSFHMI can easily convert touch stimuli into a stable electrical signal at the trigger pressure from a finger touch, without requiring an external power supply. A skeleton spacer has been specially designed in order to increase the stability and homogeneity of the output signals of each TENG unit and prevent crosstalk between them. Moreover, we constructed a hydrogel adhesive interface with skin-adhesive properties to adapt to easy wear on complex human body surfaces. By integrating the SSFHMI with a microcontroller, a programmable touch operation platform has been constructed that is capable of multiple interactions. These include medical calling, music media playback, security unlocking, and electronic piano playing. This self-powered, cost-effective SSFHMI holds potential relevance for the next generation of highly integrated and sustainable portable smart electronic products and applications. [ABSTRACT FROM AUTHOR]

The low mechanical reliability and integration failure are key challenges hindering the commercialization of geometrically flexible batteries. This work proposes that the failure of directly integrating flexible batteries using traditional rigid adhesives is primarily due to the mismatch between the generated stress at the adhesive/substrate interface, and the maximum allowable stress. Accordingly, a stress redistribution adhesive layer (SRAL) strategy is conceived by using elastic adhesive to redistribute the generated stress. The function mechanism of the SRAL strategy is confirmed by theoretical finite element analysis. Experimentally, a polyurethane (PU) type elastic adhesive (with maximum strain of 1425%) is synthesized and used as the SRAL to integrate rigid cells on different flexible substrates to fabricate directly integrated flexible battery with robust output under various harsh environments, such as stretching, twisting, and even bending in water. The SRAL strategy is expected to be generally applicable in various flexible devices that involve the integration of rigid components onto flexible substrates. [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]

In this paper, a novel flexible piezoelectric thick-film generator is proposed to address the challenges caused by flexible deformation and high piezoelectricity. This improves the output charge of the generator, which breaks the limitation imposed by the rigid and brittle nature of traditional piezoelectric bulks on elastic strain and piezoelectric performance. Additionally, the low piezoelectric coefficient of piezoelectric polymer-based piezoelectric generators is also resolved. Given the high thickness precision of electrohydrodynamic jet printing technology, the facile production of 10-μm thick film components is achieved through a process of printing and layer-by-layer accumulation on a flexible substrate, which ensures the flexible deformation and piezoelectric characteristics of the functional film. To ensure that AC is converted into stable DC output, a bipolar charge collection circuit is developed. The printed thick film produces an excellent performance in surface uniformity and smoothness. Notably, the piezoelectric constant d 33 is measured to be approximately 80 pC/N, which is five times higher than the d 33 value of flexible PVDF films. Additionally, the strength of adhesion between the printed thick film and the flexible substrate is remarkably high, reaching up to 20 N, which is an order of magnitude higher than the magnetron sputtering method. In a single cycle, the forward charge output reaches an impressively high level of 260 nC, which is approximately thirteen times the charge transfer capability of PVDF flexible generator. Furthermore, a bipolar charge collection circuit is applied to convert AC into DC effectively. This increases the output voltage from 2 V to 4 V. The illumination of commercial electronic screens and 39 LED lights demonstrates the applicability of micron-scale jet-printed thick films in micro-energy harvesting. [ABSTRACT FROM AUTHOR]

In the work i tis investigated the intense coudition of lirnear viscoelastic (Maxwell type) thread at a cross-section blow by wedge havig flat frontal part. I tis supposed that a defeectiv part of the thread fits the surface of the blowing body. The problem is solved at a subsonic mode with the condition on threads break. In many fields of modern industry, materials having elastic as well as viscous properties are used. The given thesis is dedicated to one of such questions, i.e. there is studied a behavior of a viscous-elastic fiber (Maxwells model) at a normal blow on it with a rigid wedge and a wedge with a flat front part and constant velocity. [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]

Polyvinyl Alcohol (PVA) has been used in various applications, including the medical health industry and electronics. It is a synthetic polymer with advantages such as being transparent, flexible, biocompatible, biodegradable, and a simpler synthesis process. These advantages make PVA a very promising material for human wearable antennae. In this research, the bending effect of an antenna using a PVA substrate is studied to analyze its durability in the wearable application. Firstly, the thin film substrate synthesis is performed using PVA 2488 with the measured average dielectric constant and tangent loss of 1.24 and 0.066, respectively, across S-Band frequency. Later, a 5G antenna is designed and fabricated using the PVA substrate. Finally, the bending effects of the fabricated antenna are measured at different bending radii. Four different antenna-bending radii are selected to represent different curvatures of human body parts. Results show that bending does not have a significant effect on the reflection coefficient of the antenna, where the frequency shifts from 2.2% up to 7.4% only for all bending conditions. Hence, in that aspect of finding, the PVA thin film is a potential candidate for flexible and wearable antenna material in various human body parts in biomedical applications. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials are capable of realizing the direct conversion between heat and electricity, holding a giant prospect in the sustainable development of modern society. Conductive polymers (CPs) are suitable for the preparation of TE materials given their low-cost, lightweight, flexible, and easy processing properties. With the accelerating pace of flexible composite development, there is intensive interest in their emerging applications in various aspects such as wearable electronics and thermoelectric sensors. In order to further improve the thermoelectric properties, a series of new methods have been proposed to prepare conductive polymer-based thermoelectric composites and improve their thermoelectric properties. In this review, we discuss the compositing methods, properties, and applications of conductive polymer-based TE composites. The challenges and future development directions in the design and application of conductive polymer matrix composites are also pointed out. [ABSTRACT FROM AUTHOR]

pH regulation in human biofluids is a crucial step for disease diagnosis and health monitoring. Traditional pH sensors are limited by their bulky size in wearable systems, and fragile glass tips require frequent calibration, thus limiting their use in continuous monitoring. Flexible sensors, particularly those utilizing microwires and thread-based substrates, present advantages for small sample analysis, including natural breathability and suitability for bandage or textile integration. This study examines iridium oxide and silver–silver chloride coated on thin gold wires, fabricated using sol–gel and dip-coating processes known for their simplicity. The flexible microwires demonstrated promising pH performance from a study of their pH characteristics, sensitivity, hysteresis, and potential drift. Electrodes tested in microwells allowed for small sample volumes and localized pH measurement in a controlled environment. Additional integration into fabrics for sweat sensing in wearables highlighted their potential for continuous, real-time health monitoring 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]

Metasurface absorbers have shown significant potential in stealth applications due to their adaptability and capacity to reduce the backscattering of electromagnetic (EM) waves. Nevertheless, due to the materials used in the terahertz (THz) range, simultaneously achieving excellent stealth performance in ultrawideband remains an important and difficult challenge to overcome. In this study, an ultrawideband absorber is proposed based on indium tin oxide (ITO) and polyethylene-terephthalate (PET), with a structure thickness of only 0.16λ. ITO sheets are utilized to achieve broad-spectrum, optical transparency and flexibility of the metasurface. The results show that absorption higher than 90% can be achieved in the frequency band ranging from 1.75 to 5 THz under normal TE and TM polarizations, which covers a wide THz band. The structure is insensitive to polarization angles and exhibits 97% relative bandwidth above 90% efficiency up to an oblique incident angle of 60°. To further validate the efficiency of the absorption performance, the radar cross-section (RCS) reduction investigation was performed on both planar and conformal configurations. The findings show that under normal incidence EM waves, both flat and curved surfaces can achieve RCS reduction of over 10 dB, covering an extremely wide frequency range of 1.75 to 5 THz. The metasurface presented in this study exhibits significant potential for use in several THz applications, including flexible electronic devices and stealth aircraft windows. [ABSTRACT FROM AUTHOR]

The utilisation of curved structural components is prevalent, despite their proneness to degradation over time. This research introduces a wearable and flexible electromagnetic non-destructive testing instrument that is furnished with an eddy current sensor, multi-channel excitation and acquisition circuits, amplifiers, as well as signal processing circuits. A unique design for the flexible Eddy Current Testing (ECT) sensor is suggested to ensure its suitability for diverse curved surfaces. By combining the sensor with gloves, it facilitates wearable inspection. Leveraging the self-developed instrument system, this sensor can detect defects with a minimum depth of 0.1 mm while also being capable of identifying crack orientation accurately. Furthermore, it quantitatively determines the depth of defects on curved surfaces with high signal-to-noise ratios. The instrument system exhibits high portability, flexibility, and efficiency, rendering it readily adaptable for various applications. [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]

Flexible perovskite solar cells often experience constant or cyclic bending during their service life. Catastrophic failure of devices may occur due to the crack of polycrystalline perovskite films and delamination at the perovskite and the substrate interfaces, posing a significant stability concern. Here, a multiple dynamic hydrogen bonding polymer network is developed to enhance the mechanical strength of flexible perovskite solar cells in two ways. The main chain of poly(acrylic acid) decreases the mismatch of the coefficient of thermal expansion between the perovskite and the substrate by 16.7% through its flexibility and spatial occupation. The dopamine branch chains provide multiple dynamic hydrogen bonding sites, which contribute to increased energy dissipation upon stress deformation and reduce Young's modulus of perovskite by 54.3%. The inverted flexible perovskite solar cells achieve a champion power conversion efficiency of 23.02% and retain 81.3% of the initial PCE over 2000 h under continuous 1‐sun equivalent illumination. Moreover, devices show excellent mechanical stability by remaining 90.2% of the original value after 5000 bending cycles. [ABSTRACT FROM AUTHOR]

In the past, hard electromagnetic wave (EMW) absorbing materials have made breakthroughs in performance improvement, but poor machinability limits their practical applications. Herein, a series of flexible borate ester bonded hydrogels with different water content for EMW absorption were prepared through a simple ultraviolet curing method. By adjusting the water content, the EMW absorption performance of hydrogel can be improved. When the water content reaches 30%, the minimum reflection loss (RLmin) of the hydrogel can be up to -48.70 dB at 1.89 mm and the widest effective absorption bandwidth (EABw, RL ≤ -10 dB) is 5.60 GHz (covering the entire Ku band) when the matching thickness is between 2.09 and 2.17 mm. The efficient absorption performance of the hydrogel benefits from the dipole polarization of water molecules and the interfacial polarization caused by interaction with the polymer network framework under the changing electromagnetic field. In addition, tensile and compressive experiments show that the hydrogel possesses favorable flexibility. This study provides an idea for the preparation of flexible electromagnetic attenuation devices, and the as-synthesized hydrogels have a broad application scenario in the field of wearable EMW-absorbing materials. [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]

In this work, the development of a flexible Double‐Gate (DG) organic thin film transistor (DG‐OTFT), and its employment is reported for the realization of multimodal tactile sensors. Due to the self‐encapsulation of the stacked DG architecture, highly stable organic transistors are obtained that show almost negligible degradation after 6 months. Moreover, such configuration is also very useful for the development of sensing devices. In the case, one of the two gates is used to bias and set the working point of the devices, whereas the second one is connected to a polyvinylidene fluoride(PVDF)‐capacitor, a pyro/piezoelectric material. It is demonstrated that the charge displacement induced by the PVDF capacitor due to an applied external pressure or due to a temperature variation led to a reproducible variation of the device's output current. Using this approach high‐performing multimodal tactile sensors are obtained with sensitivity to up to 241 nA N−1 and 442 nA °C−1 respectively. [ABSTRACT FROM AUTHOR]

To obtain a high-performance extended gate field-effect transistor for pH detection, hafnium nitride (HfN) was first fabricated on an indium tin oxide on polyethylene terephthalate (ITO/PET) substrate using a high-power impulse magnetron sputter system (HiPIMS) in this study. It can be easily applied in biomedical diagnostic and environmental monitoring applications with the advantages of flexible, disposable, cost-effective, and reliable components. Various duty cycle conditions in HiPIMSs were designed to investigate the corresponding sensing performance and material properties including surface morphology and composition. As the duty cycle increased, the grain size of HfN increased. Additionally, X-ray photoelectron spectroscopy (XPS) analysis illustrated the presence of HfOxNy on the deposited HfN surface. Both behaviors could result in a better pH sensing performance based on the theory of the site-binding model. Subsequently, HfN with a 15% duty cycle exhibited excellent pH sensitivity and linearity, with values of 59.3 mV/pH and 99.8%, respectively; its hysteresis width and drift coefficient were −1 mV and 0.5 mV/h, respectively. Furthermore, this pH-sensing performance remained stable even after 2000 repeated bending cycles. These results indicate the potential and feasibility of this HiPIMS-deposited HfN for future wearable chemical applications. [ABSTRACT FROM AUTHOR]

Ultralow-density (35–60 mg·cm–3) Yb2O3 nanofibrous membranes (YbFMs) with a multilayer structure were successfully prepared for the first time using Yb-acetylacetone coordination polymer as a precursor. Thanks to the high ceramic yield (62.1%) and excellent spinnability of the precursor, the YbFMs exhibited outstanding flexibility, which does not cause damage even when bent or knotted. The tensile strength of the YbFMs was 1.69 MPa, and the maximum elongation could reach 33%. Notably, the YbFMs exhibited robust fatigue resistance, retaining 87.2% of the initial stress even after 500 buckling cycles and preserving 84.75% of the initial stress in compression resilience. Moreover, the YbFMs exhibited flexibility and compressive performance in the temperature range of −196–1350 °C. The thermal conductivity of the YbFMs was 28.9–34.6 mW·m–1·K–1. At a hot surface temperature of 1350 °C, the 6 mm thick YbFMs could reduce the back temperature by about 1070 °C. Thus, YbFMs are expected to be a flexible insulation material at extremely high temperatures. [ABSTRACT FROM AUTHOR]

Flexible and miniaturized photodetectors, offering a fast response across the ultraviolet (UV) to millimeter (MM) wave spectrum, are crucial for applications like healthcare monitoring and wearable optoelectronics. Despite their potential, developing such photodetectors faces challenges due to the lack of suitable materials and operational mechanisms. Here, the study proposes a flexible photodetector composed of a monolayer graphene connected by two distinct metal electrodes. Through the photothermoelectric effect, these asymmetric electrodes induce electron flow within the graphene channel upon electromagnetic wave illumination, resulting in a compact device with ultra‐broadband and rapid photoresponse. The devices, with footprints ranging from 3 × 20 µm2 to 50 × 20 µm2, operate across a spectrum from 325 nm (UV) to 1.19 mm (MM) wave. They demonstrate a responsivity (RV) of up to 396.4 ± 5.1 mV W−1, a noise‐equivalent power (NEP) of 8.6 ± 0.1 nW Hz−0.5, and a response time as small as 0.8 ± 0.1 ms. This device facilitates direct imaging of shielded objects and material differentiation under simulated human body‐wearing conditions. The straightforward device architecture, aligned with its ultra‐broadband operational frequency range, is anticipated to hold significant implications for the development of miniaturized, wearable, and portable photodetectors. [ABSTRACT FROM AUTHOR]

Flexible pressure sensors are valuable in applications such as electronic skin, smart robots, artificial prosthetics, and wearable electronics. In this study, a fully packaged, flexible, self‐powered, long‐term stable sensor array based on piezoelectrets is developed for pressure monitoring. A pressure sensor with a microcavity structure and a thickness of 500 µm achieved an impressive piezoelectric coefficient of 23.8 pC N−1 and a fast response time of 93 ms. The sensor yielded an output voltage of 0.26 V when subjected to a force using 0.3 g soybeans, and it displayed a remarkable linear relationship (R2 = 0.992) between force and electricity with pressure ranging from 1.4 to 13.6 N and a sensitivity of 9 mV N−1. Real‐time monitoring of sound vibration, radial artery pulse, and finger movement is demonstrated along with the successful recording of dynamic pressure changes within the porcine knee joint. It holds potential for fields such as monitoring pressure changes in the movement of human bodies and robotics and can contribute significantly to pressure assessment during total knee replacement. [ABSTRACT FROM AUTHOR]

Nanoengineering polar oxide films have attracted great attention in energy storage due to their high energy density. However, most of them are deposited on thick and rigid substrates, which is not conducive to the integration of capacitors and applications in flexible electronics. Here, an alternative strategy using van der Waals epitaxial oxide dielectrics on ultra‐thin flexible mica substrates is developed and increased the disorder within the system through high laser flux. The introduction of defects can efficiently weaken or destroy the long‐range ferroelectric ordering, ultimately leading to the emergence of a large numbers of weak‐coupling regions. Such polarization configuration ensures fast polarization response and significantly improves energy storage characteristics. A flexible BiFeO3‐BaTiO3 (BF‐BT) capacitor exhibits a total energy density of 43.5 J cm−3 and an efficiency of 66.7% and maintains good energy storage performance over a wide temperature range (20–200 °C) and under large bending deformation (bending radii ≈ 2 mm). This study provides a feasible approach to improve the energy storage characteristics of dielectric oxide films and paves the way for their practical application in high‐energy density capacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] Chiral two-dimensional (2D) conductive polymers, encompassing chiral, 2D, flexible, and conductive properties, constitute a novel class of material that remains largely unexplored. The infusion of chirality into 2D conductive polymers taps into the unique characteristics associated with chirality, presenting opportunities to enhance or tailor the electronic, optical, and structural properties of materials for specific technological applications. In this study, we synthesized a chiral 2D PEDOT:PMo 11 V nanofilm through interfacial polymerization, effectively integrating a chiral monolayer, conductive polymer, and inorganic cluster. The inclusion of inorganic cluster serves to enhance the conductivity of the resulting chiral nanofilm. Furthermore, we demonstrated the chiral nanofilm as a capable electrochemical sensor for detecting drug enantiomers. The inherent flexibility of the chiral nanofilm also lays the groundwork for the development of chiral flexible/wearable devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochromic devices (ECD) are widely used to regulate the transmittance of sunlight by applying a small voltage, but the drawbacks like complex layer-by-layer preparation procedures and inconvenient assembling process still exist. To address these problems, gel or solution-type all-in-one ECDs were recently developed for the simple structure, however, the leakage risk and absence of flexible large-area production have limited real applications. Herein, a novel all-solid-state and all-in-one flexible ECD was reported by originally developed polymer dispersed electrochromic device (PDECD) strategy. This all-solid-state flexible ECD could be efficiently prepared only by one step of phase separation without any extra treatment, and demonstrated outstanding stability (92.1 % of original ΔT remained after 10,000 cycles), high coloration efficiency (197 cm2/C), low power consumption (86.4 μW/cm2) and satisfied response time (≤12 s). Meanwhile, the stored power in ECD during coloring process could drive a LED with excellent cyclic stability (93 % of original capacity remained after 3000 cycles), implying that ECD could also serve as an idea electrochromic supercapacitor. What'more, a reported largest viologen-based all-solid-state flexible ECD (17.8 × 13.2 cm2) with robust bending resistance (up to 1000 bending cycles) was successfully fabricated with industrial roller coating technique, which indicated the huge potential in real world. [ABSTRACT FROM AUTHOR]

Flatfoot is a structural and functional deformity of the foot that might change ground reaction force variables of gait. Evaluating the components of ground reaction force in three dimensions during gait is considered clinically important. This study aimed to investigate the components of ground reaction force, impulse, and loading rate during gait in people with flexible and rigid flatfoot compared to healthy subjects. 20 young women with flatfoot in two experimental groups (10 with rigid flatfoot and 10 with flexible flatfoot) and 10 healthy women in the control group participated in this study. Ground reaction force components during gait were measured using two force plates. The peak of ground reaction forces, impulse, and loading rate were then extracted. Data were processed and analyzed using MATLAB and SPSS software. One-way ANOVA with a significant level (P˂0.05) was used for statistical analysis. The results showed that peak braking force was higher in the rigid flatfoot group than in the control group (p = 0.016) and the flexible flatfoot group (p = 0.003). The posterior force loading rate was significantly higher in the rigid flatfoot group than in the flexible flatfoot group (P = 0.04). There was no significant difference in vertical loading rate between groups (P˃0.05). Since the maximal posterior ground reaction force was higher in the subjects with rigid flatfoot than in those with flexible flatfoot and healthy subjects, the increase in posterior ground reaction force is associated with an increase in anterior shear force at the knee. [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]

Printed micro‐supercapacitors (MSCs) have shown broad prospect in flexible and wearable electronics. Most of previous studies focused on printing the electrochemically active materials paying less attention to other key components like current collectors and electrolytes. This study presents an all‐printing strategy to fabricate in‐plane flexible and substrate‐free MSCs with hierarchical encapsulation. This new type of "all‐in‐one" MSC is constructed by encapsulating the in‐plane interdigital current collectors and electrodes within the polyvinyl‐alcohol‐based hydrogel electrolyte via sequential printing. The bottom electrolyte layer of this fully printed MSCs helps protect the device from the limitation of conventional substrate, showing excellent flexibility. The MSCs maintain a high capacitance retention of 96.84% even in a completely folded state. An optimal electrochemical performance can be achieved by providing ample and shorter transport paths for ions. The MSCs using commercial activated carbon as the active material are endowed with a high specific areal capacitance of 1892.90 mF cm−2 at a current density of 0.3 mA cm−2, and an outstanding volumetric energy density of 9.20 mWh cm−3 at a volumetric power density of 6.89 mW cm−3. For demonstration, a thermo‐hygrometer is stably powered by five MSCs which are connected in series and wrapped onto a glass rod. This low‐cost and versatile all‐printing strategy is believed to diversify the application fields of MSCs with high capacitance and excellent flexibility. [ABSTRACT FROM AUTHOR]

Temperature can reflect vital activities, and researchers have attempted to guide Chinese medicine diagnosis and treatment by observing acupoint temperature changes. Integrating a temperature sensor at the needle tip enables in situ acupoint temperature measurement. However, the sensor needles for acupoint temperature monitoring designed in previous studies were fabricated by manually soldering thermistor beads and metal wires, making mass production difficult. In this work, using MEMS manufacturing technology, a flexible temperature sensor that can be integrated at the needle tip is proposed and can be mass-produced on silicon wafers. The sensor uses a Pt thermistor as the temperature-sensing element and has a slender flexible structure with dimensions of 125 μm width by 3.2 cm length. As the sensor is inserted into a hollow needle, the Pt thermistor is glued to the needle tip. In the temperature range of 30 °C to 50 °C, the fabricated temperature sensor has a sensitivity of 5.00 Ω∙°C−1, a nonlinearity of ±0.39%FS, and a repeatability error of ±2.62%FS. Additionally, the sensor has been applied to in vivo acupoint temperature monitoring experiments in rats and demonstrated good performance, suggesting its promise for future research on acupoint temperature. [ABSTRACT FROM AUTHOR]

Flexible thermoelectric generators are leading candidates for next‐generation energy‐harvesting devices. Although SiGe, an environmentally‐friendly semiconductor, is the most reliable and widely tested thermoelectric material, it is difficult to form a SiGe layer with high thermoelectric performance at temperatures lower than the heat‐proof temperature of flexible plastic films. In this article, the synthesis of SiGe thermoelectric thin films via the metal‐induced layer exchange phenomenon is reviewed, from its mechanism to device performance. The selection of metal species allows low‐temperature formation (≤500 °C) of p‐ and n‐type SiGe on insulating substrates. Currently, the maximum power factors near room temperature are 850 µW m−1 K−2 for p‐type Si0.4Ge0.6 and 1000 µW m−1 K−2 for n‐type Si0.85Ge0.15. These values are the highest among those of Group IV semiconductor thin films formed at low temperatures. The flexible thermoelectric generator consisting of these p‐ and n‐type SiGe exhibits cross‐sectional and planar power densities of ≈3.0 mW cm−2 and 0.50 µW cm−2, respectively, at a temperature difference of 30 K. Finally, the future challenges of layer exchange for improving the performance of flexible thermoelectric generators based on Group IV semiconductors are discussed. [ABSTRACT FROM AUTHOR]

Abstract Mask face recognition has recently gained increasing attention in the current context. Face mask occlusion seriously affects the performance of face recognition systems, because more than 75% of the face area remains unexposed and the mask directly causes an increase in intra-class differences and a decrease in inter-class separability in the feature space. To improve the performance of face recognition model against mask occlusion, we propose a fast and efficient method for mask generation in this paper, which can avoid the need for large-scale collection of real-world mask face training sets. This approach can be embedded in the training process of any mask face model as a module and is very flexible. Experiments on the MLFW, MFR2 and RMFD datasets show the effectiveness and flexibility of our approach that outperform the state-of-the-art methods.

Abstract 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 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.

One SMEG can generate a maximum V oc and I sc of 0.57 V and 66 μA when a small amount of LiCl is dropped on one side at ambient humidity. V oc and I sc reach up to 3.55V and 204 μA when six SMEGs are connected in series or in parallel. The series connection of six SMEGs successfully lit an LED and a calculator, respectively. [Display omitted] In response to the energy crisis caused by the exhaustion of fossil energy sources, as well as to combat global warming and achieve carbon neutrality, a sandwiched-structure fabric-based moisture-enabled electricity generator (SMEG) has been developed. Cotton fabric coated with MWCNT and PEDOT: PSS solution is used as the upper and bottom electrodes, while the acid-treated cotton fabric with coating PVA and HCl hydrogel electrolyte serves as the middle layer. A single SMEG can generate a maximum open-circuit voltage (V oc) of 0.44 V and a maximum short-circuit current (I sc) of 30 μA. When a drop of LiCl is dripped on one side of SMEGs, the maximum V oc and I sc increases to 0.57 V and 66 μA, respectively. The decline in output performance slows down when LiCl is applied. The V oc increases almost linearly in series and reaches 3.55 V when six SMEGs are connected, while the I sc increases linearly in parallel and reaches 204 μA when six SMEGs are connected. The maximum power density of a single SMEG yields 0.29 μW/cm2 with an external resistance of 1 kΩ. The series connection of six SMEGs successfully lit an LED and a calculator under ambient humidity conditions, demonstrating their potential application in small electronics. [ABSTRACT FROM AUTHOR]