Cyclic Bending Research Articles

Retina-Inspired Flexible Visual Synaptic Device for Dynamic Image Processing.

Exploiting biomimetic perception of invisible spectra in flexible artificial human vision systems (HVSs) is crucial for real-time dynamic information processing. Nevertheless, the fast processing of motion objects in natural environments poses a challenge, necessitating that these artificial HVSs simultaneously have swift photoresponse and nonvolatile memory. Here, inspired by the human retina, we propose a flexible UV neuromorphic visual synaptic device (NeuVSD) based on GaOx@GaN-composited nanowires for dynamic visual perception. Benefiting from the combined action of oxygen adsorption kinetics on the GaOx shell and photoelectronic excitation in the GaN core, the NeuVSD can achieve rapid photoresponse and long-term plasticity simultaneously, a feature that surpasses traditional devices based on persistent photoconductivity mechanisms. Beyond the optoelectronic synaptic plasticity, the flexible NeuVSD on the PET/PI substrate exhibits good performance stability after 1000 bending cycles, profiting from the high adaptability of nanowires. Furthermore, target recognition and motion detection with weak light intensities are achieved through the establishment of neuromorphic visual neural networks, relying on dynamic exposures and edge information processing, respectively. Real-time edge detection can still be realized under a 40% noise factor and effectively remove the noise background. The flexible NeuVSD array-based artificial visual system can enhance the capability of dynamic visual information processing in low-light and high-noise conditions, thereby fostering the evolution of in-sensor computing and artificial intelligence.

Mechanically Resilient and Highly Efficient Flexible Perovskite Solar Cells with Octylammonium Acetate for Surface Adhesion and Stress Relief.

Flexible perovskite solar cells (FPSCs) have advanced significantly because of their excellent power-per-weight performance and affordable manufacturing costs. The unsatisfactory efficiency and mechanical stability of FPSCs are bottleneck challenges that limit their application. Here, we explore the use of octylammonium acetate (OAAc) with a long, intrinsic, flexible molecular chain on perovskite films for surface adhesion and mechanical releasing. The results showed that OAAc with high structural flexibility and strong molecular interactions can act as a mechanical release layer in releasing residual tensile stress, confirmed by the film and device characterizations as well as finite-element simulation. Moreover, the passivation of the OAAc could increase the formation energy of defects including I vacancy, Pb vacancy, and Pb-I antisite. The experimental results showed that the trap states of perovskites were significantly suppressed after OAAc modification, which is beneficial to the construction of high-quality films. With a high open-circuit voltage of 1.196 V, the efficiency of the OAAc-treated devices increased from 23.14% to 25.47% on a rigid substrate (23.12% on a flexible substrate), yielding superior long-term and mechanical durability. The corresponding flexible device retains 74% of the initial value even after 8000 bending cycles at a bending radius of 5 mm.

Super Strong Bonding at the interface between ETL and Perovskite for Robust Flexible Optoelectronic Devices.

Organic-inorganic hybrid perovskites have demonstrated great potential for flexible optoelectronic devices due to their superior optoelectronic properties and structural flexibility. However, mechanical deformation-induced cracks at the buried interface and delamination from the substrate severely constrain the optoelectronic performance and device lifespan. Here, we design a two-site bonding strategy aiming to reinforce the mechanical stability of the SnO2/perovskite interface and perovskite layer using a multifunctional organic salt, 4-(trifluoromethoxy)phenylhydrazine hydrochloride (TPH). This approach significantly enhances the bonding at the buried interface between the electronic transport layer and perovskite layer, which is demonstrated by TPH-modified SnO2/perovskite interface remaining intact after 10,000 bending cycles. Meanwhile, TPH mitigates void formation, enhances perovskite crystallinity at the buried interface, and inhibits ion migration inside the devices. Furthermore, incorporating TPH in perovskite bulk decreases the nucleation activation energy and accelerates nucleation, leading to high-quality perovskite film. Consequently, power conversion efficiencies (PCEs) of 21.64% and 23.61% are achieved for target flexible and rigid perovskite solar cells, respectively. The target flexible device retained 92.3% of its initial PCE after 25,000 bending cycles. This approach provides a robust solution for enhancing the mechanical durability of flexible perovskite optoelectronic devices.

Printed Lithography of Graphene-Perovskite Quantum Dot Hybrid Photodetectors on Paper Substrates.

Paper is an ideal platform for creating flexible and eco-friendly electronic systems. Leveraging the synergistic integration of zero- and two-dimensional materials, it unfolds a broad spectrum of applications within the realm of the Internet of Things (IoT), spanning from wearable electronics to smart packaging solutions. However, for paper without a polymer coating, the rough and porous nature presents significant challenges as a substrate for electronics, and the absence of well-established fabrication methods further hinders its application in wearable electronics. In this study, we present photodetectors (PDs) on a paper substrate composed of graphene and CsPbBr3 perovskite quantum dots (PQDs). Hybrid structures that combine PQDs with graphene offer a promising approach for PDs. These structures benefit from robust quantum confinement in PQDs alongside improved light interaction, tunable spectra, high absorption coefficients, and an enhanced photoconductive gain mechanism in graphene, all at ambient conditions. We use a microplotter for the lithographic printing of graphene, silver electrodes, and PQDs, to fabricate PDs on paper. These PDs have an external responsivity of ∼82,000 AW-1 at 520 nm for an operating voltage ⩽1 V. The external responsivity is 3 orders of magnitude higher than state-of-the-art paper-based PDs. Under bending at L0/L = 1.15 (L0 is the arc length and L is the chord length) and after 600 bending cycles, the external responsivity is maintained up to 80%. Thus, the combination of zero- and two-dimensional materials via microplotting on a paper substrate shows promise for wearable and flexible applications.

Optimizing electrical resistivity in flexible conductive films via silver nanowire doping

Silver nanowires (AgNWs) have attracted significant research interest due to their potential in conductive films, flexible electronics, electromagnetic interference (EMI) shielding, sensors, energy storage, and integration into wearable devices. This study developed conductive inks with tailored viscosities for fabricating films with stable electrical resistance. The formulations were optimized for screen printing, inkjet printing, and direct writing by doping AgNWs into carbon paste dispersed in N,N-dimethylformamide (DMF). Flexible conductive circuits were printed on silk film substrates, and their electrical resistance was evaluated by varying AgNWs concentration and the number of printed layers. Cyclic bending and energizing heating experiments were conducted to assess durability. The results demonstrated that doping with AgNWs significantly reduced film resistivity, with a concentration of 30 mg/ml being optimal for screen-printing, inkjet, and direct printing. Screen-printed films exhibited the lowest resistivity, decreasing from 1.2 × 10-4 Ω·cm to 3.5 × 10-5 Ω·cm with increasing AgNWs concentration from 5 to 30 mg/ml. The resistivity of inkjet-printed and direct-written films at 30 mg/ml AgNWs was 5.8 × 10-5 Ω·cm and 7.2 × 10-5 Ω·cm, respectively. Increasing the number of printed layers from 1 to 7 further reduced resistivity by 62% for screen printing, 58% for inkjet printing, and 55% for direct writing. Cyclic bending tests showed that after 1000 bending cycles, the resistance increased by 18% for screen-printed films, 25% for inkjet-printed films, and 30% for direct-written films. Screen-printed films exhibited the lowest resistivity and longest service life, highlighting their potential for diverse applications in flexible electronics and the broader electronics industry.

Preparation of CoNi‐LDH‐Modified Polypropylene‐Based Carbon Fiber Membranes for Flexible Supercapacitors

ABSTRACTThe rapid development of flexible electronic devices has placed higher demands on the development of high‐performance flexible supercapacitors. In this work, a safe and simple method was developed to prepare cobalt–nickel layered double hydroxide (CoNi‐LDH) flexible electrodes. Metal–organic framework (MOF)‐derived CoNi‐LDH was successfully grown on the surface of polypropylene nonwoven flexible carbon fiber membranes through plasma oxidation treatment, grafting of cobalt‐based MOFs, and room‐temperature etching in Ni2+ solution. The prepared flexible modified carbon fiber membrane (CPO‐CoNi‐40‐0.5) has good mechanical properties with a tensile strength of 159.26 ± 63.03 kPa. In addition, the CPO‐CoNi‐40‐0.5 electrode has a high specific capacitance of 580 F g−1 at 1 A g−1. The assembled supercapacitor maintains 99% of the initial specific capacity after 7000 cycles and 98% of the initial specific capacity when it is folded at 90°, showing excellent long cycle stability and bending resistance. This paper provides a new way to promote the development of high‐performance and low‐cost flexible electrodes.

Smart Bioelectronic Nanomesh Face Masks with Permeability and Flexibility for Monitoring Cortisol in Saliva.

Bioelectronic face masks can easily collect biomarkers in saliva, in which free cortisol is abundant. However, conventional bioelectronic face masks involve significant challenges in terms of permeability and inhalation due to their nonpermeable film-type structure. Herein, we introduce a flexible and permeable nanomesh-based wearable biosensor designed for bioelectronic face masks that monitor cortisol levels. The diameter of the nanofiber matrix has a range of 200 to 500 nm and offers outstanding flexibility (2% resistance change at a bending radius of 2 mm), reliability (0.3% resistance change at a bending radius of 5 mm after 1000 bending cycles), and permeability (116.91 g m-2 h-1 at 18 °C with 40% humidity, which is 10 times higher compared with film) based on the nanoporous structure. We evaluated the electrochemical responses of functionalized interdigitated electrodes on a flexible and permeable poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanomesh. Our nanomesh cortisol biosensors demonstrated exceptional sensitivity to cortisol, even at low concentrations, with a detection limit as low as 10 pM. Furthermore, we measured cortisol in clinical samples, such as artificial saliva and human saliva, using nanomesh-based bioelectronic face masks. This study highlights the potential for further applications of bioelectronic face masks for detecting numerous biomarkers.

High‐Density, Crosstalk‐Free, Flexible Electrolyte‐Gated Synaptic Transistors Array via All‐Photolithography for Multimodal Neuromorphic Computing

AbstractHigh‐density bio‐electrolyte‐gated synaptic transistors (BEGTs) array are promising for constructing neuromorphic computing architectures. Due to the bulk ion conductivity and the crack sensitivity of the electrolyte film, patterning the electrolyte is an indispensable route to prevent spatial crosstalk and improve the flexibility of the device array. However, the susceptibility of bio‐electrolyte to organic solvents poses challenges in developing reliable all‐photolithography techniques for fabricating scalable, patterned, and high‐density BEGTs array. This study introduces an all‐photolithography method that adopts a photo‐crosslinker‐enabled electrolyte to create a high‐density (11846 devices per cm2) multimodal BEGTs array. This array demonstrates essential neuromorphic behaviors without inter‐device crosstalk and maintains its flexibility, enduring 200 bending cycles at a 6 mm radius without significant performance degradation. Meanwhile, the BEGTs array exhibits multimodal synaptic behavior, not only successfully mimicking the biological visual memory system for sensing and processing images but also proving highly accurate in classifying handwritten digits, making it suitable for constructing neuromorphic computing systems. This work offers a dependable strategy for the scalable and stable fabrication of BEGTs array, providing valuable insights for advancing artificial neuromorphic systems.

High-Mobility All-Transparent TFTs with Dual-Functional Amorphous IZTO for Channel and Transparent Conductive Electrodes.

The increasing demand for advanced transparent and flexible display technologies has led to significant research in thin-film transistors (TFTs) with high mobility, transparency, and mechanical robustness. In this study, we fabricated all-transparent TFTs (AT-TFTs) utilizing amorphous indium-zinc-tin-oxide (a-IZTO) as a dual-functional material for both the channel layer and transparent conductive electrodes (TCEs). The a-IZTO was deposited using radio-frequency magnetron sputtering, with its composition adjusted for both channel and electrode functionality. XRD analysis confirmed the amorphous nature of the a-IZTO layers, ensuring structural stability post-thermal annealing. The a-IZTO TCEs demonstrated high optical transparency (89.57% in the visible range) and excellent flexibility, maintaining a low sheet resistance with minimal degradation even after 100,000 bending cycles. The fabricated AT-TFTs exhibit superior field-effect mobility (30.12 cm2/V·s), an on/off current ratio exceeding 108, and a subthreshold swing of 0.36 V/dec. The AT-TFT device demonstrated a minimum transmittance of 75.46% in the visible light range, confirming its suitability for next-generation flexible and transparent displays.

Molecular dynamics simulation of bending behavior of B2-FeAl alloy nanowires with different crystallographic orientations

In nanosystems, the metallic nanowires are subjected to significant and cyclic bending deformation upon integration into stretchable and flexible nanoelectronic devices. The reliability and service life of these nanodevices depend fundamentally on the bending mechanical properties of the metallic nanowires that serve as the critical components. A deep understanding of the deformation behavior of the metallic nanowires under bending is not only essential but also imperative for design and manufacture of high-performance nanodevices. To explore the mechanism underlying the bending plasticity of the metallic nanowire, we have conducted a study on the bending deformation of B2-FeAl alloy nanowires with various crystallographic orientations, sizes and cross-sectional shapes by using molecular dynamics simulation. Our results show that the bending behavior of the B2-FeAl alloy nanowires is independent of the size and cross-sectional shape of the nanowire, but it is highly sensitive to its axial orientation. Specifically, both <111>- and <110>-oriented nanowires yield by dislocation nucleation upon bending, in which the <111>-oriented nanowire fails by brittle fracture soon after yielding, while the <110>-oriented nanowire exhibits good ductility due to homogeneous plastic flow raised by continuous nucleation and steady motion of dislocations. In contrast to the aforementioned two nanowires, the bending plasticity of the <001>-oriented nanowire is mediated by stress-induced transformation from B2 to L1<sub>0</sub> phases, which leads to excellent ductility and higher fracture strain. The orientation dependence of bending deformation can be understood by considering the Schmid factor. Moreover, the plastically bent nanowires with <110> and <001> orientations are able to recover to their original shape upon unloading, particularly, the plastic deformation in the <001>-oriented nanowire is recoverable completely via reverse transformation from L1<sub>0</sub> to B2 structures, exhibiting superelasticity. This work elucidates the deformation mechanism of the B2-FeAl alloy nanowire subjected to bending load, which provides a crucial insight for the design and optimization of flexible and stretchable nanodevices based on metallic nanowires.

Highly sensitivity and wide-range flexible humidity sensor based on LiCl/cellulose nanofiber membrane by one-step electrospinning

Cellulose is considered an ideal material for flexible electronic humidity sensors due to its green renewable nature, rich surface groups and strong hydrophilicity. However, the traditional cellulose-based humidity sensor cannot simultaneously have wide detection range, high sensitivity and fast response time, which seriously hinder their development and application. Here, an ultrathin Lithium chloride (LiCl)/cellulose nanofiber membrane as moisture sensitive materials was prepared by one-step electrospinning and used to assemble a high-performance humidity sensor. N, N-Dimethylacetamide/Lithium chloride (DMAc/LiCl) solvent system was used to dissolve the cellulose, and DMAc volatilized into the air while LiCl remained in the cellulose nanofibers during the electrospinning process. LiCl as a highly moisture-sensitive inorganic salt has strong hydrophilicity and enhances the moisture sensing detection limit of cellulose fiber (especially under low humidity conditions), thus giving the cellulose moisture sensor excellent sensitivity (up to 4191 %) and a wide detection range (5–98 % RH). The nanometer size of cellulose fibers, the extremely low thickness and large pores of cellulose membranes accelerate the mass exchange of moisture between the air and the membrane, thus giving cellulose humidity sensor a fast response/recovery time (99/110 s) and low hysteresis (2.9 %). Moreover, the performances of humidity sensors didn’t degrade even after being subjected to long-term application (>30 days), high/low temperatures (73.6/0.1 ℃) and thousands of bending cycles. The proposed LiCl/cellulose nanofiber humidity sensor brings innovative solutions for the design of cellulose based sensor with great potential for use in non-contact humidity detection, respiratory monitoring and sleep apnea detection applications.

Laser writing of metal-oxide doped graphene films for tunable sensor applications.

Flexible and wearable devices play a pivotal role in the realm of smart portable electronics due to their diverse applications in healthcare monitoring, soft robotics, human-machine interfaces, and artificial intelligence. Nonetheless, the extensive integration of intelligent wearable sensors into mass production faces challenges within a resource-limited environment, necessitating low-cost manufacturing, high reliability, stability, and multi-functionality. In this study, a cost-effective fiber laser direct writing method (fLDW) was illustrated to create highly responsive and robust flexible sensors. These sensors integrate laser-induced graphene (LiG) with mixed metal oxides on a flexible polyimide film. fLDW simplifies the synthesis of graphene, functionalization of carbon structures into graphene oxides and reduced graphene oxides, and deposition of metal-oxide nanoparticles within a single experimental laser writing setup. The preparation and surface modification of dense oxygenated graphene networks and semiconducting metal oxide nanoparticles (CuO x , ZnO x , FeO x ) enables rapid fabrication of LiG/MO x composite sensors with the ability to detect and differentiate various stimuli, including visible light, UV light, temperature, humidity, and magnetic fluxes. Further, this in situ customizability of fLDW-produced sensors allows for tunable sensitivity, response time, recovery time, and selectivity. The normalized current gain of resistive LiG/MO x sensors can be controlled between -2.7 to 3.5, with response times ranging from 0.02 to 15 s, and recovery times from 0.04 to 6 s. Furthermore, the programmable properties showed great endurance after 200 days in air and extended bend cycles. Collectively, these LiG/MO x sensors stand as a testament to the effectiveness of fLDW in economically mass-producing flexible and wearable electronic devices to meet the explicit demands of the Internet of Things.

A Sustainable and Flexible Carbon Paper-Based Multifunctional Human-Machine Interface (HMI) Sensor.

We have executed a cost-effective approach to produce a high-performance multifunctional human-machine interface (HMI) humidity sensor. The designed sensors were ecofriendly, flexible, and highly sensitive to variability in relative humidity (%RH) in the surroundings. In this study, we have introduced a humidity sensor by using carbon paper (as both a substrate and sensing material) and a silver (Ag) conductive ink pen. The carbon paper-based humidity sensor was developed by using a simple handwriting approach and the resulting devices exhibited excellent results including fast response/recovery times (12/24 s), a wide sensing range (30 to 85%), small hysteresis (1.1%), high stability (1 month), and repeatability. This high-performance humidity response could be attributed to the highly porous, hydrophilic, and permeable nature of carbon paper. Besides these features, the sensor offered high flexibility (100 bending cycles across different radii) and adaptability for uses like breath monitoring (through mouth and nose), proximity sensing (from multiple distances ranging from 1 to 10 cm), and depicting Morse code. This research work is a significant step forward in humidity sensing technology and the sustainable future of electronic devices by using a cost-effective, fast, and simple fabrication technique.

Evaluation of 3D robotic spray parameters on the performance of the developed sensing functional cementitious coating

ABSTRACT This study explores the innovative use of 3D robotic spray for applying self-sensing cementitious coating, emphasising its potential for multifunctional smart concrete applications. The effects of spray parameters on the performance of self-sensing cementitious composites were investigated by systematically examining the impact of nozzle travel speed, air injection pressure, nozzle standoff distance, and spray direction on the self-sensing coating. In-depth analyses were conducted on mechanical strength, coating adhesion properties, and sensing performance. Micro-CT was performed to investigate the coating's inherent porosity. This study evaluated the sensing performance of the coatings by analysing their piezoresistive behaviour under cyclic compression and bending. Furthermore, it demonstrated the coating's capacity for real-time structural health monitoring by evaluating its performance under compressive and bending stresses until failure. This research underscores the significant impact of spray parameters on optimising the sensing capabilities of the self-sensing spray coating, highlighting its potential for advanced real-time structural health monitoring.

In-Situ Cross-Linked Polymers for Enhanced Thermal Cycling Stability in Flexible Perovskite Solar Cells.

Flexible perovskite solar cells (FPSCs) are a promising emerging photovoltaic technology, with certified power conversion efficiencies reaching 24.9 %. However, the frequent occurrence of grain fractures and interface delamination raises concerns about their ability to endure the mechanical stresses caused by temperature fluctuations. In this study, we employ an in situ polymerization molecule with extended functional end groups to preserve mechanical integrity during thermal cycling. The AMPS-DEA molecule chemically anchors to grain boundaries and cross-links neighboring grains, protecting the structure from stress accumulation. Additionally, its hydroxyl groups form bidentate chelation with SnO2, enhancing interfacial adhesion and preventing delamination. More importantly, the relaxed residual stress provided by AMPS-DEA allows the perovskite layer to adapt to temperature changes, effectively matching adjacent layers and preventing mechanical failure. Our findings demonstrate that AMPS-DEA modification not only boosts PCE to 25.78 % in rigid PSCs and 24.54 % in flexible PSCs but also improves stability, maintaining over 95 % efficiency after 10,000 bending cycles and 200 thermal cycles.

In‐Situ Cross‐Linked Polymers for Enhanced Thermal Cycling Stability in Flexible Perovskite Solar Cells

Flexible perovskite solar cells (FPSCs) are a promising emerging photovoltaic technology, with certified power conversion efficiencies reaching 26.61%. However, the frequent occurrence of grain fractures and interface delamination raises concerns about their ability to endure the mechanical stresses caused by temperature fluctuations. In this study, we employ an in‐situ polymerization molecule with extended functional end groups to preserve mechanical integrity during thermal cycling. The AMPS‐DEA molecule chemically anchors to grain boundaries and cross‐links neighboring grains, protecting the structure from stress accumulation. Additionally, its hydroxyl groups form bidentate chelation with SnO2, enhancing interfacial adhesion and preventing delamination. More importantly, the relaxed residual stress provided by AMPS‐DEA allows the perovskite layer to adapt to temperature changes, effectively matching adjacent layers and preventing mechanical failure. Our findings demonstrate that AMPS‐DEA modification not only boosts PCE to 25.78% in rigid PSCs and 24.54% in flexible PSCs but also improves stability, maintaining over 95% efficiency after 10,000 bending cycles and 200 thermal cycles.

High Performance of Cs2AgBiBr6 Perovskite-based Photodetectors by Adding DEAC.

Perovskite-based photodetectors (PDs) are broadly utilized in optical communication, non-destructive testing, and smart wearable devices due to their ability to convert light into electrical signals. However, toxicity and instability hold back their mass production and commercialization. The lead-free Cs2AgBiBr6 double perovskite film, promised to be an alternative, is fabricated by electrophoretic deposition (EPD), which compromises film quality. Herein, we improved the quality of the Cs2AgBiBr6 films and the performance of PDs by adding N-acetylethylenediamine (DEAC) to Cs2AgBiBr6 perovskite precursor for EPD, in which the ligand DEAC provides a pair of lone electrons to Bi3+, forming coordinate covalent bonds. The optimized PDs have high detectivity, up to 4.4×1012 Jones, and high stability in the air. The high-performance, flexible Cs2AgBiBr6 perovskite PDs were fabricated on this basis, it also achieved the detectivity up to 3.2×1012 Jones with excellent bending cycle stability. These results propose a feasible approach to improving the crystallization of double perovskite thin films by introducing ligands during the EPD process. Furthermore, they demonstrate enhanced optoelectronic performance, indicating that this method is also applicable to halide perovskites, offering an effective strategy to improve their film quality.

Bending Fatigue Behavior Analysis and Fatigue Life Prediction of Spot-Welded Steel T-Profiles: An XFEM Analysis

Steel T-profiles are extensively used across various sectors due to their versatility and reliability. Spot welding plays a crucial role in their production. These profiles are subjected to cyclic bending loads in numerous engineering applications. Understanding the failure mechanisms is essential for enhancing fatigue resistance and extending the operational lifespan of spot-welded assemblies. Key aspects include accurately predicting where damage initiates, how it propagates under increasing cyclic loads, and the failure point. For this purpose, XFEM analysis was conducted and validated with experimental results from the literature. The study emphasizes the significant impact of bending moment magnitude, load ratio, the diameter of spot welds, and component thickness on the fatigue performance of spot-welded assemblies under bending loads. All these parameters significantly affected the fatigue response. Notably, thinner components showed 8.55 times faster crack propagation, accompanied by more localized and severe cracking.

Cellulose-based encapsulation for all-printed flexible thermoelectric touch detectors

Printed and flexible electronics have gained considerable scientific attention in recent years, driving the demand for low-energy production techniques, eco-friendly materials and flexible substrates. However, effective encapsulation is essential to protect these devices in harsh environmental conditions. Thus, sustainable encapsulant materials are critical for advancing flexible electronics. In this work, we studied three encapsulant materials—commercial plastic, polyvinyl alcohol and ethyl cellulose—applied to thermoelectric touch sensors printed on paper and fabric substrates. Ethyl cellulose demonstrated promising properties in terms of flexibility, water resistance and transparency, along with a low carbon footprint. Encapsulated substrates with ethyl cellulose exhibited high contact angles (121° on fabric and 116° on paper), indicating robust water repellency. Thermal stability tests showed minimal mass loss (10%) at 315 °C, confirming its temperature resilience. Furthermore, sensors encapsulated with ethyl cellulose retained their electric performance after water submersion for 1 min and withstood 100 bending cycles, maintaining response times below 1 s and signal output around 100 µV. These findings highlight ethyl cellulose as a viable green encapsulant material compatible with large-scale sustainable electronics manufacturing.

HfO2 Memristor-Based Flexible Radio Frequency Switches.

Flexible and wearable electronics are experiencing rapid growth due to the increasing demand for multifunctional, lightweight, and portable devices. However, the growing demands of interactive applications driven by the rise of AI reveal the inadequate connectivity of current connection technologies. In this work, we successfully leverage memristive technology to develop a flexible radio frequency (RF) switch, optimized for 6G-compatible communication systems and adaptable to flexible applications. The flexible RF switch demonstrates a low insertion loss (2 dB) and a cutoff frequency exceeding 840 GHz, and performance metrics are maintained after 106 switching cycles and 2500 mechanical bending cycles, showing excellent reliability and robustness. Furthermore, the RF switch is fully integrable with a photolithography-processable polyimide (PSPI) substrate, enabling efficient 2.5D integration with other RF components, such as RF antennas and interconnects. This technology holds significant promise to advance 6G communications in flexible electronics, offering a scalable solution for high-speed data transmission in next-generation wearable devices.