Bending States Research Articles

Emulating learning behavior in a flexible device with self-formed Ag dewetted nanostructure as active element

Neuromorphic devices are a promising alternative to the traditional von Neumann architecture. These devices have the potential to achieve high-speed, efficient, and low-power artificial intelligence. Flexibility is required in these devices so that they can bend and flex without causing damage to the underlying electronics. This feature shows a possible use in applications that require flexible electronics, such as robotics and wearable electronics. Here, we report a flexible self-formed Ag-based neuromorphic device that emulates various brain-inspired synaptic activities, such as short-term plasticity and long-term potentiation (STP and LTP) in both the flat and bent states. Half and full-integer quantum conductance jumps were also observed in the flat and bent states. The device showed excellent switching and endurance behaviors. The classical conditioning could be emulated even in the bent state.

An Improved Static Model for Bidirectional Notched Continuum Robot Considering the Cable Tension Loss

Abstract The notched continuum mechanism is particularly suitable for natural orifice transluminal surgery benefiting from its small size and hollow structure. However, the widely used kinematic model based on constant curvature assumption does not reveal the actual deformation of the continuum mechanism, and its control accuracy is unstable, while the general mechanics model has the problem that the tension of the distal driving cable is difficult to measure. In this paper, a nonconstant curvature static model for a bidirectional V-shaped notched continuum mechanism is presented. The deformation of each part of the continuum mechanism from the distal end to the proximal end is analyzed in turn. The tension loss of the driving cable caused by the contact with the continuum mechanism is modeled using the capstan equation. The recursive equation between the deformation of each part of the continuum mechanism from the proximal end is derived, which can be solved numerically. The bending state of the continuum mechanism can then be estimated when only the tension of the proximal flexible cable is known. The model is experimentally verified by driving the continuum mechanism to move at a very low speed. The experiment results show that the estimation effect of the proposed model is significantly improved compared with that of the constant curvature model.

Simulated bending test analysis of 23% efficient lead-free flexible perovskite solar cell with different bending states

Perovskite solar cells (PSCs) have emerged as a promising technology for developing highly efficient and low-cost photovoltaic (PV) devices. However, toxicity is the primary limiting factor that is restraining the use of traditional PSCs. Therefore, lead-free PSCs have been considered the best alternative due to lead toxicity and environmental impact. The secondary obstacle hindering the potential of PSCs for wearable applications is their limited flexibility. Therefore, lead-free flexible PSC (F-PSC) device is designed and simulated through the Silvaco-TCAD tool in this work. Despite the significant advancements made in F-PSCs, insufficient research is conducted to examine their performance under different bending states to study the reliability of the device’s flexibility. Here, three different bending states have been reported to investigate the proposed device performance, viz. convex, concave, and sinusoidal. The impact of bending radius (BR) in convex and concave from 5 to 20 mm and bending amplitude (BA) in the sinusoidal state from 0.5 to 2 mm is studied and analyzed to optimize the device performance. The performance of the proposed lead-free F-PSC is explored in terms of the current density (JV) curve, PV parameters, and external quantum efficiency (EQE). Optimized PV parameters of the proposed F-PSC are: short-circuit current density (JSC) of 33.45 mA cm−2, open-circuit voltage (VOC) of 0.925 V, fill factor (FF) of 77.15% and PCE of 23.87%. The findings of the reported study would significantly provide a path for the development of F-PSC.

Design of Single-Mode Single-Polarization Large-Mode-Area Multicore Fibers.

In laser science and industry, considerable effort is directed toward designing fibers for fiber laser and fiber amplifier applications, each of which offers a particular advantage over the others. Evanescently coupled multicore fibers, however, have been studied less extensively due to the relatively small mode area in the single-mode regime. Here, by proposing a new structure with stress-applying parts in a 37-core fiber and optimizing this structure through a comprehensive framework, we present 21 solutions characterized by large-mode-area and high beam quality in the single-mode, single-polarization regime. Different fiber designs are optimal for different output parameters. In one design, the mode area can significantly increase to above 880 μm2, which is comparable with that of photonic-crystal fibers. Moreover, besides the single-mode operation, the beam quality factor (M2 factor) of the fundamental mode is considered an output parameter in the bent state and is improved up to 1.05 in another design. A comprehensive tolerance analysis is then performed to assess the performance of the designs under deviations from normal conditions. Moreover, in spite of the shifts in the loss of modes, the proposed high beam quality LMA fibers maintain single-polarization, single-mode operation across a wide range of core pitches, bending orientation angles, and bending radius deviations. Our results highlight the potential of multicore fibers for the efficient operation of fiber lasers and amplifiers.

Near-Infrared-Induced NO-Releasing Photothermal Adhesive Hydrogel with Enhanced Antibacterial Properties.

Bacterial infection and the development of antibiotic-resistant bacteria have decreased the effectiveness of traditional antibiotic treatments for wound healing. The design of a multifunctional adhesive hydrogel with antibacterial activity, self-healing properties, and on-demand removability to promote wound healing is highly desirable. In this work, a photothermal cyclodextrin with a NO-releasing moiety has been incorporated within an oxidized sodium alginate conjugated polyacrylamide (OS@PA) hydrogel to get a photothermal NO-releasing GSNOCD-OS@PA hydrogel. Such a multifunctional hydrogel has the unique feature of combined antibacterial activity as a result of a controlled photothermal effect and NO gas release under an 808 near-infrared laser. Because of oxidized sodium alginate (OSA), the hydrogel matrix easily adheres to the skin under twisted and bent states. In vitro cytotoxicity analysis against 3T3 cells showed that the hydrogels OS@PA and GSNOCD-OS@PA are noncytotoxic under laser exposure. The temperature-induced NO release by GSNOCD-OS@PA reached 31.7 mg/L when irradiated with an 808 nm laser for 10 min. The combined photothermal therapy and NO release from GSNOCD-OS@PA effectively reduced viability of both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) to 3 and 5%, respectively. Importantly, the phototherapeutic NO-releasing platform displayed effective fibroblast proliferation in a cell scratch assay.

Deposition of MnO2 on KOH-activated laser-produced graphene for a flexible planar micro-supercapacitor

The rapid development of flexible supercapacitors has been impeded by the difficulty of preparing flexible electrodes. We report the fabrication of a highly flexible and conductive microporous graphene-based substrate obtained by direct laser writing combined with KOH activation, which we call activated laser-produced graphene (a-LPG), which is then decorated with electrochemically deposited MnO2 to form a flexible a-LIG/MnO2 thin-film electrode. This hybrid electrode has a high areal capacitance of 304.61 mF/cm2 at a current density of 1 mA/cm2 in a 1 mol/L Na2SO4 aqueous electrolyte. A flexible asymmetric supercapacitor with a-LIG/MnO2 as the anode, a-LIG as the cathode and PVA/ H3PO4 as a gel electrolyte was assembled, giving an areal energy density of 2.61 μWh/cm2 at a power density of 260.28 μW/cm2 and an ultra-high areal capacitance of 18.82 mF/cm2 at 0.2 mA/cm2 with 90.28% capacitance retained after 5 000 cycles. It also has an excellent electrochemical performance even in the bent state. This work provides an easy and scalable method to design high-performance flexible supercapacitor electrodes and may open a new way for their large-scale fabrication.

Cable-Driven and Series Elastic Actuation Coupled for a Rigid–Flexible Spine-Hip Assistive Exoskeleton in Stoop–Lifting Event

This article presents a design of an electrically powered spine-hip assistive exoskeleton (SHAE) to relieve back muscle fatigue of industrial workers and prevent back injuries. The rigid–flexible coupling driving realizes the performance of the system in terms of comfort, weight, flexibility, system durability, and industrial feasibility. It uses only two series elastic actuators (SEAs), coupled to drive two hip joints and one bio-inspired spine mechanism. The SEA is realized by the ball screw driving the elastic slider, which is, respectively, transmitted to the spine mechanism and the hip joints in cable driving mechanism and crank-slider mechanism. This device can distribute power to wearer's back and hips during a stoop–lifting event. In the state of lateral bending, axial rotation, and walking of the wearer, it can meet the needs of flexible movement of human body with the advantages of good back driving performance and low impedance. Furthermore, in order to transmit the torque determined by a high-level controller, an SEA force controller is implemented by measuring the elastic displacement of the spring unit installed in the slider. To evaluate the effectiveness of the developed exoskeleton mechanism, we experimentally verified the feasibility of different motion modes. Finally, the effectiveness of SHAE in assisting the waist was verified by collecting and comparing the electromyography signals of the relevant muscles of the waist during stoop–lifting exercise of the subjects with and without wearing the SHAE.

Flexible germanium monotelluride phase change films with ultra-high bending stability for wearable piezoresistive sensors

Although non-stoichiometric chalcogenide phase change materials (e.g., Ge2Sb2Te5, Sb2Te3) have been used in wearable electronics, their non-stoichiometric vacancies will inevitably degrade their bending stability and electrical contrast. In this study, we demonstrated that stoichiometric germanium monotelluride films deposited on flexible polyimide substrates exhibited excellent phase transition characteristics and ultra-high bending stability under different bending states. The GeTe films showed improved bending stability under compressive strain than under tensile strain, and the GeTe films still exhibited high conductivity contrast (6 orders of magnitude) after 2000 bending cycles, with potential use in flexible memory devices. As a proof-of-concept, the bending stability of the stoichiometric GeTe films was shown to be significantly better than the non-stoichiometric Ge2Sb2Te5 films. Notably, we fabricated a flexible piezoresistive sensor based on the GeTe film, which exhibited good sensitivity (gauge factor is 38), low detection limit (0.1%), short response time (83.3 ms), good reliability and repeatability (more than 1200 cycles) and high heat resistance (200 ℃), and was used to track human pulse, as well as finger and face movements. The results showed that the piezoresistive sensor had good sensitivity and a stable time-resolved electrical response, and could be used to detect the movement of different human body parts and the small signals of different pressure points. These findings indicated that GeTe-based wearable piezoresistive sensors hold significant promise for medical health monitoring and biosensing applications.

Chitin and cellulose as constituents of efficient, sustainable, and flexible zinc-ion hybrid supercapacitors

A zinc-ion hybrid supercapacitor (ZIHS) is a prospective energy storage device featuring cost-effectiveness, operational safety, environmental friendliness, high-power performance, and satisfied energy density. The sustainability of this ZIHS technology is even improved by introducing biopolymer constituents into the cell construction. Herein, efficient, sustainable, and flexible ZIHSs employing polysaccharide (chitin- or cellulose-based) components are developed. Using green ionic liquid solvents, biopolymer-bound, activated carbon-based cathode materials and hydrogel biopolymer electrolytes containing conductive zinc salts are obtained. According to systematical characterization results, the prepared materials possess favorable functional properties. Biopolymer binders provide homogeneity and integrity within the electrode network and high adhesion to the surface of the current collector. Depending on the type of zinc salt, hydrogel biopolymer electrolytes display high ionic conductivity (up to 46 mS cm−1), expanded electrochemical stability window (up to ca. 2.8 V), and zinc dendrites growth suppression. Biopolymer components assembled with zinc foil electrodes operate efficiently in both coin and pouch ZIHS cell configurations, providing satisfactory energy (45–50 Wh kg−1) and high power (10–20 kW kg−1) density combined with excellent cycle stability. Moreover, these ZIHS pouch-type devices exhibit superior durability and flexibility, withstanding mechanical stress up to 150° bending states with at least 90% of capacitance retention. It suggests a prospect for their application in wearable electronics.

Finite element analysis of the knee joint stress after partial meniscectomy for meniscus horizontal cleavage tears

ObjectiveTo establish a finite element model of meniscus horizontal cleavage and partial resection, to simulate the mechanical changes of knee joint under 4 flexion angles, and to explore what is the optimal surgical plan. MethodsWe used Mimics Research, Geomagic Wrap, and SolidWorks computer software to reconstruct the 3D model of the knee joint, and then produced the horizontal cleavage tears model of the internal and lateral meniscus, the suture model, and the partial meniscectomy model. These models were assembled into a complete knee joint in SolidWorks software, and corresponding loads and boundary constraints were added to these models in ANSYS software to simulate the changing trend of pressure and shear force on femoral condylar cartilage, meniscus, and tibial cartilage under the flexion angles of 0°, 10°, 20°, 30° and 40° of the knee joint. At the same time, the difference of force area between medial interventricular and lateral interventricular of knee joint under four states of bending the knee was compared, to explore the different effects of different surgical methods on knee joint after horizontal meniscus tear. ResultsWithin the four medial meniscus injury models, the lowest peak internal pressure and shear force of the knee joint was observed in the meniscal suture model; the highest values were found in the bilateral leaflet resection model and the inferior leaflet resection model; the changes of pressure, shear force and stress area in the superior leaflet resection model were the most similar to the changes of the knee model with the meniscal suture model. ConclusionSuture repair is the best way to maintain the force relationship in the knee joint. However, resection of the superior leaflet of the meniscus is also a reliable choice when suture repair is difficult.

A flexible metamaterial absorber with temperature-insensitive design at microwave frequencies

Developing a metamaterial absorber (MA) with both flexibility and temperature insensitivity continues to be a challenge in the field of radar stealth. In this paper, we propose a compensation method for designing flexible and temperature-insensitive MA. This method is revealed through the relationship between the square resistance of the resistive film, the permittivity of the substrate, and the temperature. Importantly, the compensation method is applicable to both the MA in the plane state and the bending state. By utilizing the benefits of the compensation mechanism and the flexible designability of the bilayer cross-shaped structure, the flexible MA proposed in this paper can achieve temperature-insensitive absorption across a broad frequency range. Experimental results indicate that the absorption peaks achieve an absorptivity greater than 90% within the frequency of 7.2–9.4 GHz, exhibiting excellent temperature stability from 25 °C to 300 °C. In comparison to previous studies on flexible MAs, this design offers a distinct advantage in high-temperature environments and provides valuable guidelines for the design of integrated multi-functional absorbers in practical applications.

Experimental investigation on seismic behavior of the precast shear wall systems with different connection methods under the coupling action of axial tension and cyclic horizontal load

The grouting sleeve connection and lapped steel bars connection are widely used for the connection, while they often require skilled workers, concealed work, and high installation accuracy, and can be expensive and cause significant damage to horizontal construction joints under earthquakes or extreme winds. To address these issues, based on the lap-spliced connection, the angle steel connectors were installed on the precast shear walls and foundation beams to improve the shear resistance and connection performance of horizontal construction joints and reduce construction issues. In practice, shear walls in high-rise structures may experience the coupling action of axial tension and cyclic horizontal load under strong earthquakes or extreme winds, resulting in an unfavorable state of tension bending or tension shear coupling stress for the shear wall systems. As the height-width ratio of these structures increases, there is a significantly increased possibility of shear wall structures experiencing tension bending or tension shear. In this study, five shear walls with different connection methods were manufactured and tested under the coupling action of axial tension and cyclic horizontal load. And the results suggested that the shear resistance of precast concrete shear walls at the horizontal construction joint significantly influenced their seismic performance and concrete damage when subjected to axial tension and cyclic horizontal loads. The precast shear wall system that utilized lapped steel bars and angle steel connectors for connections exhibited the best seismic performance. Additionally, the continuous horizontal construction joint formed by integral prefabrication (containing the edge components) slightly reduced the seismic behavior of the novel precast shear wall system utilizing lapped steel bars and angle steel connectors. The new precast shear wall system utilizing angle steel connectors has the potential to be an effective means of providing seismic resistance in high-rise structures that are subjected to the coupling action of axial tension and cyclic horizontal load.

All‐In‐One Hardware Devices with Event‐Based Vision Sensor Arrays for Image Sensing, Computing, and Learning

AbstractMetal oxide semiconductors (MOSs) are considered as potential candidates for the low‐cost, large‐area fabrication of flexible optoelectronic devices. However, the current optoelectronic devices based on MOSs are limited to unidirectional photoresponse, which constrains the performance of MOSs‐based vision sensors for artificial vision systems. Herein, for the first time, a flexible artificial vision system integrated with optical perception, computation, and learning functionalities is demonstrated using SnO optoelectronic synaptic transistor‐based event‐driven vision sensors to enable dynamic image perception, noise reduction, detection, and recognition. Specifically, an ambipolar SnO transistor is demonstrated by introducing HfO2 passivation layer, which facilitates the movement of O atoms around Sn‐vacancy sites to the HfO2 layer to achieve the transformation from p‐type to ambipolar transport behaviors. More importantly, the HfO2‐passivated SnO transistors exhibit gate‐tunable bidirectional photoresponse behavior, which is essential to simulate the neurobiological functionalities of bipolar cells. This way, the multilayer neural network learning circuit built from SnO transistors achieves fast recognition at a 16% Gaussian noise level and high recognition accuracy up to 95.2% for pattern letters. Under the bending states, recognition accuracies are still retained at 91.2%. These properties are well retained even under the influence of 100% offset of the synaptic programming value.

Designing Ordered Organic Small-Molecule Domains for Ultraviolet Detection and Micrometer-Sized Flexible Imaging.

Photodetectors displaying an ultraviolet (UV) spectral response window are typically based on wide-bandgap semiconductors that have long been dominated by inorganic materials that suffer from bottlenecks of low flexibility and a limited material family. Here, we synthesized a novel organic small molecule and controlled its crystallization to suppress leakage currents and facilitate separation of the carriers, and the relationship between the nanoscale phase separation morphology and the optoelectrical performance of the photodetectors is disclosed. Our optimized organic photodetector (OPD) presents a UV spectral response window, with superior self-powered responsivities of 45 mA/W (under 250 nm light) and 70 mA/W (under 300 nm light), outperforming the Si photodiode and rivaling other reported UV self-powered photodetectors. Finally, an imaging system was constructed to demonstrate the application potential of the OPD in UV flexible imaging with high-resolution arrays of 400 pixels × 400 pixels (5 μm × 5 μm per pixel), which could work in bent states and successfully output images of micrometer-sized objects.

Flexible Stacked Perovskite Photodetectors for High-Efficiency Multicolor Fluorescence Detection.

A flexible, multicolor detector based on stacked perovskite layers with graded band gaps was presented. Different perovskite layers generate a series of photocurrents corresponding to light intensities at different wavelengths. Experimentally, the flexible detector demonstrated acceptable long-term stability and temperature stability in the bending state. To demonstrate the advantages of the flexible multicolor detector in biological applications, a tubular-shaped multicolor fluorescence detector that embraces the sample cell was constructed. As a result, the detection limits of three kinds of CdTe quantum dots (QDs) with central wavelengths of 545, 625, and 730 nm were 0.52, 0.85, and 0.43 nM, respectively, which was significantly improved by more than 10 times compared to those of planar detectors. Additionally, the detector was able to detect three kinds of QDs simultaneously in a mixed solution, and the relative deviation was smaller than 10% compared to the preset concentration. These results demonstrate that the flexible stacked perovskite detector and the tubular-shaped detection configuration hold promise for the simultaneous fluorescent detection of multiple biomolecules.

Li + HF and Li + HCl Reactions Revisited I: QCT Calculations and Simulation of Experimental Results.

The Li + HF and Li + HCl reactions share some common features. They have the same kinematics, relatively small barrier heights, bent transition states, and are both exothermic when the zero point energy is considered. Nevertheless, the pioneering crossed beam experiments by Lee and co-workers in the 80s (Becker et al., J. Chem. Phys. 1980, 73, 2833) revealed that the dynamics of the two reactions differ significantly, especially at low collision energies. In this work, we present theoretical simulations of their results in the laboratory frame (LAB), based on quasiclassical trajectories and obtained using accurate potential energy surfaces. The calculated LAB angular distributions and time-of-flight spectra agree well with the raw experimental data, although our simulations do not reproduce the experimentally derived center-of-mass (CM) differential cross section and velocity distributions. The latter were derived by forward convolution fitting under the questionable assumption that the CM recoil velocity and scattering angle distribution were uncoupled, while our results show that the coupling between them is relevant. Some important insights into the reaction mechanism discussed in the article by Becker et al. had not been contrasted with those that can be extracted from the theoretical results. Among them, the correlation between the angular momenta involved in the reactions has also been examined. Given the kinematics of both systems, the reagent orbital angular momentum, , is almost completely transformed into the rotation of the product diatom, j'. However, contrary to the coplanar mechanism proposed in the original paper, we find that the initial and final relative orbital angular momenta are not necessarily parallel. Both reactions are found to be essentially direct, although about 15% of the LiFH complexes live longer than 200 fs.

High-performance flexible UV-photodetector via self-assembled ZnO films

Zinc oxide (ZnO) is one of the most attractive materials for the preparation of ultraviolet photodetectors (UV PDs). However, the high leakage current and slow response speed significantly limit the practical applications of ZnO-based PDs. In this study, the fabrication of UV PDs based on self-assembled ZnO film has been proposed. The device has an ultra-low dark current (25 pA@10 V) and exhibits fast response speed (190 ms/68.6 ms) and high detectivity (1.91 × 1014 Jones) for 360 nm light. The high performance can be attributed to the operating mechanism of ‘light-induced reduction of junction barrier height’. The analysis based on the thermionic emission theory indicates that illumination can significantly reduce both the Schottky barrier height and series resistance of the device. The prepared flexible PD based on the self-assembled film not only maintains excellent detection performance but also has strong durability and mechanical robustness. After 1000 bending-recovery cycles, the flexible device exhibits excellent repeatable on/off photo-switching behaviors. The measured time-response curves of the flexible PD under five different bending states show unaffected photocurrent, demonstrating excellent flexibility and stability.

Bending recognition based on learning enhanced fiber specklegram sensor

In this paper, we propose and demonstrate a deep learning-enhanced fiber specklegram sensor for bending recognition. A segment of multimode fiber is used to sense bending, and tiny bending changes lead to significant variations in the speckle pattern generated at the distal end of the fiber. Principal component analysis (PCA) is utilized to optimize the collected samples and remove noise and redundant information by mining internal features, which makes the mapping relationship between the speckle image and corresponding curvature clearer and is conducive to reducing computational complexity. Back propagation neural network is employed to learn the mapping relationship between speckle image and curvature on the optimized dataset according to the optimized direction provided by PCA. The testing results show that the prediction error of the trained model for the learned bending state is 5.9 × 10−4 m−1, and the prediction speed is 0.05 ms per frame. The proposed scheme has a strong generalization ability and can be applied to predict bending states that have never been learned or seen with a prediction error of 3.8 × 10−2 m−1, which cannot be realized by the previously reported fiber specklegram sensor based on the classification neural network. The bending recognition scheme enhanced by deep learning proposed in this paper provides an enlightening reference for solving fiber sensing problems with deep learning methods, and it has the potential to be applied in more fields as a general scheme.

Hierarchical 3D Electrode Design with High Mass Loading Enabling High-Energy-Density Flexible Lithium-Ion Batteries.

Flexible lithium-ion batteries (LIBs) have attracted significant attention owing to their ever-increasing use in flexible and wearable electronic devices. However, the practical application of flexible LIBs in devices has been plagued by the challenge of simultaneously achieving high energy density and high flexibility. Herein, a hierarchical 3D electrode (H3DE) is introduced with high mass loading that can construct highly flexible LIBs with ultrahigh energy density. The H3DE features a bicontinuous structure and the active materials along with conductive agents are uniformly distributed on the 3D framework regardless of the active material type. The bicontinuous electrode/electrolyte integration enables a rapid ion/electron transport, thereby improving the redox kinetics and lowering the internal cell resistance. Moreover, the H3DE exhibits exceptional structural integrity and flexibility during repeated mechanical deformations. Benefiting from the remarkable physicochemical properties, pouch-type flexible LIBs using H3DE demonstrate stable cycling under various bending states, achieving a record-high energy density (438.6 Wh kg-1 and 20.4 mWh cm-2 ), and areal capacity (5.6 mAh cm-2 ), outperforming all previously reported flexible LIBs. This study provides a feasible solution for the preparation of high-energy-density flexible LIBs for various energy storage devices.

All-printed wearable humidity sensor with hydrophilic polyvinylpyrrolidone film for mobile respiration monitoring

In this study, a capacitive-type wearable humidity sensor comprising a polyvinylpyrrolidone (PVP) film, as active sensing dielectric, and carbon nanotube (CNT) random networks, as electrodes, all-printed on flexible substrates in ambient air, is demonstrated for real-time respiration monitoring. The PVP-based humidity sensor achieved a high sensing response of 3.0 ± 0.15 nF/RH%∙cm2 (where RH stands for relative humidity) and a sensitivity of 6.4 ± 0.1 pF/%RH in the RH range of 40–90%. A significantly small hysteresis window, fast response/recovery (∼ 30 ms), and high reliability were noted. The sensing mechanism of the capacitive response toward humidity was investigated, and it is attributed to continuous proton hopping through water molecule layers. The operational stability of the proposed humidity sensor under temperature variations and mechanical deformation, was investigated to address existing issues related to wearable electronics. Finally, the feasibility of a mobile respiration monitoring device is demonstrated by developing an armband-type wireless-communication monitoring system equipped with the wearable humidity sensor. Real-time biophysical information can be analyzed by monitoring the changes in the respiration intensity and frequency, which were wirelessly transmitted to the user’s mobile interface. We note that very few studies have focused on all-printed wearable humidity sensors consisting of pristine PVP and immobilized CNT random networks for real-time mobile respiration monitoring of human breath regardless of bent and relaxed state.