Asymmetric two-dimensional ferroelectric transistor with anti-ambipolar transport characteristics

Two-dimensional (2D) ferroelectric transistors hold unique properties and positions, especially talking about low-power memories, in-memory computing, and multifunctional logic devices. To achieve better functions, appropriate design of new device structures and material combinations is necessary. We present an asymmetric 2D heterostructure integrating MoTe₂, h-BN, and CuInP₂S₆ as a ferroelectric transistor, which exhibits an unusual property of anti-ambipolar transport characteristic under both positive and negative drain biases. Our results demonstrate that the anti-ambipolar behavior can be modulated by external electric field, achieving a peak-to-valley ratio up to 10³. We also provide a comprehensive explanation for the occurrence and modulation of the anti-ambipolar peak based on a model describing linked lateral-and-vertical charge behaviors. Our findings provide insights for designing and constructing anti-ambipolar transistors and other 2D devices with significant potential for future applications.

Silicon flexoelectronic transistors

It is extraordinarily challenging to implement adaptive and seamless interactions between mechanical triggering and current silicon technology for tunable electronics, human-machine interfaces, and micro/nanoelectromechanical systems. Here, we report Si flexoelectronic transistors (SFTs) that can innovatively convert applied mechanical actuations into electrical control signals and achieve directly electromechanical function. Using the strain gradient-induced flexoelectric polarization field in Si as a "gate," the metal-semiconductor interfacial Schottky barriers' heights and the channel width of SFT can be substantially modulated, resulting in tunable electronic transports with specific characteristics. Such SFTs and corresponding perception system can not only create a high strain sensitivity but also identify where the mechanical force is applied. These findings provide an in-depth understanding about the mechanism of interface gating and channel width gating in flexoelectronics and develop highly sensitive silicon-based strain sensors, which has great potential to construct the next-generation silicon electromechanical nanodevices and nanosystems.

Ultralight, Elastic, Hybrid Aerogel for Flexible/Wearable Piezoresistive Sensor and Solid-Solid/Gas-Solid Coupled Triboelectric Nanogenerator

Aerogels have been attracting wide attentions in flexible/wearable electronics because of their light weight, excellent flexibility, and electrical conductivity. However, multifunctional aerogel-based flexible/wearable electronics for human physiological/motion monitoring, and energy harvest/supply for mobile electronics, have been seldom reported yet. In this study, a kind of hybrid aerogel (GO/CNT HA) based on graphene oxide (GO) and carboxylated multiwalled carbon nanotubes (CMWCNTs) is prepared which can not only used as piezoresistive sensors for human motion and physiological signal detections, but also as high performance triboelectric nanogenerator (TENG) coupled with both solid-solid and gas-solid contact electrifications (CE). The repeatedly loading-unloading tests with 20 000 cycles exhibit its high and ultrastable piezoresistive sensor performances. Moreover, when the obtained aerogel is used as the electrode of a TENG, high electric output performance is produced due to the synergistic effect of solid-solid, and gas-solid interface CEs (3D electrification: solid-solid interface CE between the two solid electrification layers; gas-solid interface CE between the inner surface of GO/CNT HA and the air filled in the aerogel pores). This kind of aerogel promises good applications for human physiological/motion monitoring and energy harvest/supply in flexible/wearable electronics such as piezoresistive sensors and flexible TENG.

An Internal-Electrostatic-Field-Boosted Self-Powered Ultraviolet Photodetector

Self-powered photodetectors are of significance for the development of low-energy-consumption and environment-friendly Internet of Things. The performance of semiconductor-based self-powered photodetectors is limited by the low quality of junctions. Here, a novel strategy was proposed for developing high-performance self-powered photodetectors with boosted electrostatic potential. The proposed self-powered ultraviolet (UV) photodetector consisted of an indium tin oxide and titanium dioxide (ITO/TiO₂) heterojunction and an electret film (poly tetra fluoroethylene, PTFE). The PTFE layer introduces a built-in electrostatic field to highly enhance the photovoltaic effect, and its high internal resistance greatly reduces the dark current, and thus remarkable performances were achieved. The self-powered UV photodetector with PTFE demonstrated an extremely high on-off ratio of 2.49 × 10⁵, a responsivity of 76.87 mA/W, a response rise time of 7.44 ms, and a decay time of 3.75 ms. Furthermore, the device exhibited exceptional stability from room temperature to 70 °C. Compared with the conventional ITO/TiO₂ heterojunction without the PTFE layer, the photoresponse of the detector improved by 442-fold, and the light-dark ratio was increased by 8.40 × 10⁵ times. In addition, the detector is simple, easy to fabricate, and low cost. Therefore, it can be used on a large scale. The electrostatic modulation effect is universal for various types of semiconductor junctions and is expected to inspire more innovative applications in optoelectronic and microelectronic devices.

Elastic Kernmantle E-Braids for High-Impact Sports Monitoring

The kernmantle construction, a kind of braiding structure that is characterized by the kern absorbing most of the stress and the mantle protecting the kern, is widely employed in the field of loading and rescue services, but rarely in flexible electronics. Here, a novel kernmantle electronic braid (E-braid) for high-impact sports monitoring, is proposed. The as-fabricated E-braids not only demonstrate high strength (31 Mpa), customized elasticity, and nice machine washability (>500 washes) but also exhibit excellent electrical stability (>200 000 cycles) during stretching. For demonstration, the E-braids are mounted to different parts of the trampoline for athletes' locomotor behavior monitoring. Furthermore, the E-braids are proved to act as multifarious intelligent sports gear or wearable equipment such as electronic jump rope and respiration monitoring belt. This study expands the kernmantle structure to soft flexible electronics and then accelerates the development of quantitative analysis in modern sports industry and athletes' healthcare.

[Clinical characteristics and vaccination status of SARS-CoV-2 Omicron variant infected children]

Objective: To investigate the clinical characteristics and vaccination status of SARS-CoV-2 Omicron variant infected children. Methods: A total of 105 children infected with Omicron variant admitted to Tianjin Haihe Hospital (designated referral hospital for SARS-CoV-2 infection in Tianjin) from January 8, 2022 to February 3 were included for a retrospective study. The cases were divided into pneumonia group and non-pneumonia group according to chest imaging. Based on the doses of inactivated SARS-CoV-2 vaccine, the children who completed SARS-CoV-2 antibody test within 3 days after hospitalization were divided into 2 dose group and<2 dose group.Rank sum test and Chi-square test were used for the comparison between the groups. Results: The age of these 105 children was 10 (8, 11) years on admission, 53 children were males and 52 were females. Eighty-seven cases (82.9%) had mild symptoms, 13 cases (12.4%) had common symptoms and 5 cases (4.8%) were asymptomatic. Ninety-one cases (86.7%) completed 2 doses vaccination. The clinical symptoms were characterized by cough (74 cases, 70.5%), fever (58 cases, 55.2%), sore or dry throat (34 cases, 32.4%), nasal congestion (28 cases, 26.7%), rhinorrhea (23 cases, 21.9%). None of the children received antivirals, steroids, immunosuppressant or oxygen therapy. Seventy-six cases(72.4%) received traditional Chinese medicine treatment. The pneumonia group had a higher rate of positive SARS-CoV-2 IgG within 1 day after admission (13/13 vs. 87.0% (80/92), χ2=42.81, P<0.001) than the non-pneumonia group. Among the 62 children who had serial SARS-CoV-2 antibody tests within 3 days after hospitalization, Compared to the<2 dose group, the 2 dose group had a higher rate of nucleic acid conversion within 16 days after onset and a higher rate of positive SARS-CoV-2 IgG 1 day after admission and 3 days after hospitalization (96.4% (54/56) vs. 4/6, 100.0% (56/56) vs. 2/6, 100.0% (56/56) vs. 3/6, all P<0.05). Conclusions: Most children infected with Omicron variant have mild symptoms, mainly respiratory infection symptoms. The proportion of SARS-CoV-2 antibody IgG positive in children who have received 2 doses of inactivated SARS-CoV-2 vaccines is higher,and the time of whose nucleic acid conversion may be shortened.

Hollow Ni3Se4 with High Tap Density as a Carbon-Free Sulfur Immobilizer to Realize High Volumetric and Gravimetric Capacity for Lithium-Sulfur Batteries

Despite that the practical gravimetric energy density of lithium sulfur batteries has exceeded that of the traditional lithium-ion battery, the volumetric energy density still pales due to the low density of carbonaceous materials. Herein, hollow polar nickel selenide (Ni₃Se₄) with various architectures was designed and employed as a carbon-free sulfur immobilizer. Among them, hollow sea urchins like Ni₃Se₄ with high porosity (0.39 cm³ g^-1) and large specific surface area (82.7 m² g^-1) exhibit abundant adsorptive and electrocatalytic sites, which pledge excellent electrochemical performances of the Li-S battery. Correspondingly, the Ni₃Se₄-based sulfur electrode presents excellent rate endurability (581 mAh g^-1_-composite at 2.0 C) and superior cycle stability (ultralow fading rate of 0.042% per cycle during the 1000 cycles at 1.0 C). More importantly, thanks to the higher tap density (Ni₃Se₄/S: 1.57 g cm^-3 vs super P/S: 0.7 g cm^-3), the volumetric specific capacity of Ni₃Se₄-based cathodes is as high as 1699 mAh cm^-3_-composite at 0.1 C, which is almost 2.8 times that of the carbonaceous electrode. Hence, rational transition metal selenide architecture design with synergistic function of good conductivity, well-defined catalyst and adsorption, as well as high tap density provide a promising route toward high gravimetric and volumetric energy density of Li-S batteries.

Tactile tribotronic reconfigurable p-n junctions for artificial synapses

The emulation of biological synapses with learning and memory functions and versatile plasticity is significantly promising for neuromorphic computing systems. Here, a robust and continuously adjustable mechanoplastic semifloating-gate transistor is demonstrated based on an integrated graphene/hexagonal boron nitride/tungsten diselenide van der Waals heterostructure and a triboelectric nanogenerator (TENG). The working states (p-n junction or n⁺-n junction) can be manipulated and switched under the sophisticated modulation of triboelectric potential derived from mechanical actions, which is attributed to carriers trapping and detrapping in the graphene layer. Furthermore, a reconfigurable artificial synapse is constructed based on such mechanoplastic transistor that can simulate typical synaptic plasticity and implement dynamic control correlations in each response mode by further designing the amplitude and duration. The artificial synapse can work with ultra-low energy consumption at 74.2 fJ per synaptic event and the extended synaptic weights. Under the synergetic effect of the semifloating gate, the synaptic device can enable successive mechanical facilitation/depression, short-/long-term plasticity and learning-experience behavior, exhibiting the mechanical behavior derived synaptic plasticity. Such reconfigurable and mechanoplastic features provide an insight into the applications of energy-efficient and real-time interactive neuromodulation in the future artificial intelligent system beyond von Neumann architecture.

The discovery of a superhard P-type transparent semiconductor: Al2.69B50

Superhard semiconductors have been long sought after for electronic device applications enduring extreme conditions, such as astronautics, due to their intrinsic toughness, high thermal and chemical stability. Here, we report the superhard p-type semiconductor Al_2.69B₅₀ single crystal with the determined Vickers hardness of ∼40.5 GPa under the load of 0.49 N, which is one of the hardest semiconductor compounds that have been ever found. With the direct band gap of 2.3 eV, Al_2.69B₅₀ exhibits excellent optical transmittance (>90%), covering the visible range from 459 nm to 760 nm and part of the infrared range, and also shows the high intensity of the photon emission in the visible light. Al_2.69B₅₀ is very stable, thermally and chemically, with an ultra-low density of ∼2.52 g cm^-3, allowing for further extension of its applications. Such an assembly of various excellent properties within one material has great implication for high power electronic design and applications.

p-n Junction Based Direct-Current Triboelectric Nanogenerator by Conjunction of Tribovoltaic Effect and Photovoltaic Effect

Triboelectric nanogenerators (TENGs) have attracted much interest in recent years, due to its effectiveness and low cost for converting high-entropy mechanical energy into electric power. The traditional TENGs generate an alternating current, which requires a rectifier to provide a direct-current (DC) power supply. Herein, a dynamic p-n junction based direct-current triboelectric nanogenerator (DTENG) is demonstrated. When a p-Si wafer is sliding on a n-GaN wafer, carriers are generated at the interface and a DC current is produced along the direction of the built-in electric field, which is called the tribovoltatic effect. Simultaneously, an UV light is illuminated on the p-n junction to enhance the output. The results indicate that the current increases 13 times and the voltage increases 4 times under UV light (365 nm, 28 mW/cm²) irradiation. This work demonstrates the coupling between the tribovoltaic effect and the photovoltaic effect in DTENG semiconductors, promoting further development for energy harvesting in mechanical energy and photon energy.

Generalized temperature dependence model for anammox process kinetics

Temperature is a key operational factor influencing the anammox process kinetics. In particular, at temperatures below 15 °C, the specific anammox activity (SAA) considerably decreases. This study aimed to describe the temperature dependence of the anammox process kinetics in the temperature range from 10 to 55 °C, including the specific characteristics of "cold anammox". The commonly used Arrhenius and extended and modified Ratkowsky equations were examined. The Ratkowsky equations yielded a strong correlation (coefficient of determination, R² = 0.93-0.96) between the measured and predicted data over the analyzed temperature range (10-55 °C). However, these equations could not correctly reflect the anammox temperature dependence at temperatures below 15 °C (R² = 0.36-0.48). Therefore, a new generalized temperature model was proposed. The generalized temperature equation (GTE) considered the division of the analyzed temperature range into three temperature ranges: 10-15 °C, 15-35 °C and 35-55 °C. The ranges correspond to "cold anammox", "(low) mesophilic anammox" and "thermophilic anammox". The applied approach yielded a strong correlation between the measured and predicted SAA (R² = 0.97) over the temperature range from 10 to 55 °C and over the low-temperature range from 10 to 15 °C (R² = 0.99). Overall, the GTE could enhance the predictions of the temperature dependence of the anammox process kinetics. The GTE can help examine anammox-based bioaugmentation systems operating at both high temperatures (sidestream reactors) and low temperatures (mainstream reactors).

A composite triboelectric nanogenerator based on flexible and transparent film impregnated with ZIF-8 nanocrystals

The triboelectric nanogenerator (TENG), based on the triboelectrification coupled with electrostatic induction, can directly convert ambient mechanical energy into electric energy. However, the output performance of TENG is still low and demands further improvement to speed up the commercial application. In this work, we demonstrate a TENG based on a flexible and transparent composite film made of PDMS and ZIF-8. When the amount of the ZIF-8 is 4 wt%, the generated output current and voltage of the TENG are gradually increased up to 16.3μA and 176 V, which are 210% and 230% higher than that of TENG without ZIF-8, respectively. Impregnated ZIF-8 which exhibits a positive polarity lowers the effective work function of the PDMS and enhance the surface charge density, verified by Kelvin probe force microscope measurement.

Alternate-Layered MXene Composite Film-Based Triboelectric Nanogenerator with Enhanced Electrical Performance

The output power of the triboelectric nanogenerator (TENG) strongly depends on the performance of triboelectric materials, especially microstructures and functional groups of them. In this work, aiming at the excellent triboelectric ability, alternate-layered MXene composite films-based TENG with abundant fluorine groups(-F) through layer-by-layer stacking are designed and fabricated. Benefitting from the uniform intrinsic microstructure and increased dielectric constant, when the amount of the Nb₂CT_x nanosheets increases to 15 wt%, the TENG based on Nb₂CT_x/Ti₃C₂T_x composite nanosheets films achieves the maximum output. The short-circuit current density of 8.06 μA/cm² and voltage of 34.63 V are 8.4 times and 3.5 times over that of pure Ti₃C₂T_x films, and 3.3 times and 4.3 times over that of commercial poly(tetrafluoroethylene) (PTFE) films, respectively. Furthermore, the fabricated TENG could be attached to human body to harvest energy from human motions, such as typing, texting, and hand clapping. The results demonstrate that the alternate-layered MXene composite nanosheet films through layer-by-layer stacking possess remarkably triboelectric performance, which broaden the choice of negative triboelectric materials and supply a new choice for high output TENG.

Dynamic real-time imaging of living cell traction force by piezo-phototronic light nano-antenna array

Dynamic mapping of the cell-generated force of cardiomyocytes will help provide an intrinsic understanding of the heart. However, a real-time, dynamic, and high-resolution mapping of the force distribution across a single living cell remains a challenge. Here, we established a force mapping method based on a "light nano-antenna" array with the use of piezo-phototronic effect. A spatial resolution of 800 nm and a temporal resolution of 333 ms have been demonstrated for force mapping. The dynamic mapping of cell force of live cardiomyocytes was directly derived by locating the antennas' positions and quantifying the light intensities of the piezo-phototronic light nano-antenna array. This study presents a rapid and ultrahigh-resolution methodology for the fundamental study of cardiomyocyte behavior at the cell or subcellular level. It can provide valuable information about disease detection, drug screening, and tissue engineering for heart-related studies.

Integrative sequencing discovers an ATF1-motif enriched molecular signature that differentiates hyalinizing clear cell carcinoma from mucoepidemoid carcinoma

OBJECTIVES

Salivary gland tumors are comprised of a diverse group of malignancies with widely varying prognoses. These cancers can be difficult to differentiate, especially in cases with limited potential for immunohistochemistry (IHC)-based characterization. Here, we sought to define the molecular profile of a rare salivary gland cancer called hyalinizing clear cell carcinoma (HCCC), and identify a molecular gene signature capable of distinguishing between HCCC and the histopathologically similar disease, mucoepidermoid carcinoma (MEC).

MATERIALS AND METHODS

We performed the first integrated full characterization of five independent HCCC cases.

RESULTS

We discovered insulin-like growth factor alterations and aberrant IGF2 and/or IGF1R expression in HCCC tumors, suggesting a potential dependence on this pathway. Further, we identified a 354 gene signature that differentiated HCCC from MEC, and was significantly enriched for genes with an ATF1 binding motif in their promoters, supporting a transcriptional pathogenic mechanism of the characteristic EWSR1-ATF1 fusion found in these tumors. Of the differentially expressed genes, IGF1R, SGK1 and SGK3 were found to be elevated in the HCCCs relative to MECs. Finally, analysis of immune checkpoints and subsequent IHC demonstrated that CXCR4 protein was elevated in several of the HCCC cases.

CONCLUSION

Collectively, our data identify an ATF1-motif enriched gene signature that may have clinical utility for molecular differentiation of HCCCs from other salivary gland tumors and discover potential actionable alterations that may benefit the clinical care of recurrent HCCC patients.

A Polymeric Bilayer Multi-Legged Soft Millirobot with Dual Actuation and Humidity Sensing

There are numerous works that report wirelessly controlling the locomotion of soft robots through a single actuation method of light or magnetism. However, coupling multiple driving modes to improve the mobility of robots is still in its infancy. Here, we present a soft multi-legged millirobot that can move, climb a slope, swim and detect a signal by near-infrared irradiation (NIR) light or magnetic field dual actuation. Due to the design of the feet structure, our soft millirobot incorporates the advantages of a single actuation mode of light or magnetism. Furthermore, it can execute a compulsory exercise to sense a signal and analyze the ambience fluctuation in a narrow place. This work provides a novel alternative for soft robots to achieve multimode actuation and signal sensing.

Paper-based triboelectric nanogenerators and their applications: a review

The development of industry and of the Internet of Things (IoTs) have brought energy issues and huge challenges to the environment. The emergence of triboelectric nanogenerators (TENGs) has attracted wide attention due to their advantages, such as self-powering, lightweight, and facile fabrication. Similarly to paper and other fiber-based materials, which are biocompatible, biodegradable, environmentally friendly, and are everywhere in daily life, paper-based TENGs (P-TENGs) have shown great potential for various energy harvesting and interactive applications. Here, a detailed summary of P-TENGs with two-dimensional patterns and three-dimensional structures is reported. P-TENGs have the potential to be used in many practical applications, including self-powered sensing devices, human-machine interaction, electrochemistry, and highly efficient energy harvesting devices. This leads to a simple yet effective way for the next generation of energy devices and paper electronics.

Multifunctional Coaxial Energy Fiber toward Energy Harvesting, Storage, and Utilization

Fibrous energy-autonomy electronics are highly desired for wearable soft electronics, human-machine interfaces, and the Internet of Things. How to effectively integrate various functional energy fibers into them and realize versatile applications is an urgent need to be fulfilled. Here, a multifunctional coaxial energy fiber has been developed toward energy harvesting, energy storage, and energy utilization. The energy fiber is composed of an all fiber-shaped triboelectric nanogenerator (TENG), supercapacitor (SC), and pressure sensor in a coaxial geometry. The inner core is a fibrous SC by a green activation strategy for energy storage; the outer sheath is a fibrous TENG in single-electrode mode for energy harvesting, and the outer friction layer and inner layer (covered with Ag) constitute a self-powered pressure sensor. The electrical performances of each energy component are systematically investigated. The fibrous SC shows a length specific capacitance density of 13.42 mF·cm^-1, good charging/discharging rate capability, and excellent cycling stability (∼96.6% retention). The fibrous TENG shows a maximum power of 2.5 μW to power an electronic watch and temperature sensor. The pressure sensor has a good enough sensitivity of 1.003 V·kPa^-1 to readily monitor the real-time finger motions and work as a tactile interface. The demonstrated energy fibers have exhibited stable electrochemical and mechanical performances under mechanical deformation, which make them attractive for wearable electronics. The demonstrated soft and multifunctional coaxial energy fiber is also of great significance in a sustainable human-machine interactive system, intelligent robotic skin, security tactile switches, etc.

[The value of conventional magnetic resonance imaging based radiomic model in predicting the texture of pituitary macroadenoma]

Objective: To investigate the value of conventional magnetic resonance imaging (MRI) based radiomic model in predicting the texture of pituitary macroadenoma. Methods: The complete data of 101 patients with pituitary macroadenoma confirmed by surgery and pathology in Yijishan Hospital of Wannan Medical College from December 2014 to December 2019 were retrospectively analyzed. According to the texture of the intraoperative pituitary tumor, patients were divided into soft group (n=58) and hard group (n=43). They were randomly divided into training group (n=72) and validation group (n=29) at a ratio of 7∶3. All patients underwent conventional MRI scan of the pituitary gland. Itk-snap software was used to manually outline the T(1)-weighted image (T(1)WI), T(2)-weighted image (T(2)WI) and enhanced T(1)WI image section by section on tumor area of interest (ROI) and perform three-dimensional fusion. Then AK software was imported to extract texture features. The regression analysis methods of minimum redundancy maximum relevance (mRMR) and least absolute shrinkage and selection operator (LASSO) were used for feature selection and radiomic signature establishment. The reliability of the model was verified by 100 leave-group-out cross validation (LGOCV), and the predictive ability of the model was evaluated by drawing the receiver operating characteristic (ROC) curve. The decision curve analysis (DCA) was used to evaluate the clinical application value of the model. Results: The AUC (Area Under the ROC Curve) (95%CI) values of T1WI, T2WI, enhanced T1WI, and the combined sequence model to predict the texture of pituitary macroadenomas in the training and validation groups were 0.91 (0.84-0.98) and 0.90 (0.78-1.00), 0.86 (0.78-0.95) and 0.83 (0.64-1.00), 0.90 (0.83-0.97) and 0.89 (0.77-1.00),0.92 (0.85-0.98) and 0.91 (0.79-1.00), respectively. DCA demonstrated that T(1)WI, T(2)WI, enhanced T(1)WI, and combined sequence model all had good net benefits in clinical practice. Conclusions: T(1)WI, T(2)WI, enhanced T(1)WI, and combined sequence model of conventional MRI all had high efficacy in predicting the texture of pituitary macroadenoma, which provided a new quantitative method for predicting the texture of pituitary macroadenoma.

High precision epidermal radio frequency antenna via nanofiber network for wireless stretchable multifunction electronics

Recently, stretchable electronics combined with wireless technology have been crucial for realizing efficient human-machine interaction. Here, we demonstrate highly stretchable transparent wireless electronics composed of Ag nanofibers coils and functional electronic components for power transfer and information communication. Inspired by natural systems, various patterned Ag nanofibers electrodes with a net structure are fabricated via using lithography and wet etching. The device design is optimized by analyzing the quality factor and radio frequency properties of the coil, considering the effects of strain. Particularly, the wireless transmission efficiency of a five-turn coil drops by approximately only 50% at 10 MHz with the strain of 100%. Moreover, various complex functional wireless electronics are developed using near-field communication and frequency modulation technology for applications in content recognition and long-distance transmission (>1 m), respectively. In summary, the proposed device has considerable potential for applications in artificial electronic skins, human healthcare monitoring and soft robotics.

Dielectric and energy storage properties of Bi2O3-B2O3-SiO2 doped Ba0.85Ca0.15Zr0.1Ti0.9O3 lead-free glass-ceramics

A sol-gel method is employed for preparing high quality lead-free glass-ceramic samples (1 - x)BCZT-xBBS-incorporating Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) powder and Bi2O3-B2O3-SiO2 (BBS) glass-doped additives with different values of x (x = 0, 0.05, 0.1, 0.15). Systematic investigations are performed to comprehend the structural, dielectric and energy storage characteristics using X-ray diffraction, field-emission scanning electron microscopy, impedance and ferroelectric analyser methods. With appropriate BBS doping (x), many fundamental traits including breakdown strength, dielectric loss and energy storage density have shown significant improvements. Low doping-level samples x < 0.1 have retained the pure perovskite phase while a second glass phase appeared in samples with x ≥ 0.1. As the doping level (0.1 ≥ x > 0) is increased, the average grain size decreased to become better homogeneous materials with improved breakdown energy strengths. Excessive addition of BBS (x = 0.15) causes negative effects on microstructures and other traits. The glass-ceramic sample 0.95BCZT-0.05BBS exhibits excellent dielectric permittivity and temperature stability, with the highest energy storage density of 0.3907 J cm-3 at 130 kV cm-1. These results provide good reference to develop lead-free ceramics of high energy storage density.

Flexoelectronics of centrosymmetric semiconductors

Interface engineering by local polarization using piezoelectric^1-4, pyroelectric^5,6 and ferroelectric^7-9 effects has attracted considerable attention as a promising approach for tunable electronics/optoelectronics, human-machine interfacing and artificial intelligence. However, this approach has mainly been applied to non-centrosymmetric semiconductors, such as wurtzite-structured ZnO and GaN, limiting its practical applications. Here we demonstrate an electronic regulation mechanism, the flexoelectronics, which is applicable to any semiconductor type, expanding flexoelectricity^10-13 to conventional semiconductors such as Si, Ge and GaAs. The inner-crystal polarization potential generated by the flexoelectric field serving as a 'gate' can be used to modulate the metal-semiconductor interface Schottky barrier and further tune charge-carrier transport. We observe a giant flexoelectronic effect in bulk centrosymmetric semiconductors of Si, TiO₂ and Nb-SrTiO₃ with high strain sensitivity (>2,650), largely outperforming state-of-the-art Si-nanowire strain sensors and even piezoresistive, piezoelectric and ferroelectric nanodevices¹⁴. The effect can be used to mechanically switch the electronics in the nanoscale with fast response (<4 ms) and high resolution (~0.78 nm). This opens up the possibility of realizing strain-modulated electronics in centrosymmetric semiconductors, paving the way for local polarization field-controlled electronics and high-performance electromechanical applications.

Adsorption kinetics, conformational change, and enzymatic activity of β-glucosidase on hematite (α-Fe2O3) surfaces

Substantial fractions of extracellular enzymes are intimately associated with soil minerals, which may protect enzymes from denaturation, precipitation, proteolysis, or microbial consumption in soil environments. However, how mineral surface properties affect enzyme-mineral interactions and enzymatic activity of enzymes associated to mineral surface is still unclear. In the present study, adsorption behavior, conformational change, and enzymatic activity of β-glucosidase (BG) on hematite (001) face and (104) face, respectively, were investigated using in situ attenuated total reflectance FTIR spectroscopy and batch experiments. β-glucosidase undergoes greater conformational changes upon adsorption onto hematite (104) face than on hematite (001) face, probably due to the stronger protein-surface interactions on (104) face with the relatively higher surface hydroxyl density. On the other hand, the amount of BG sorbed on hematite (001) face was nearly two times higher than that on hematite (104) at the end of the 150-min adsorption experiments, due to the higher extent of conformational change in β-glucosidase on hematite (104) face. Correspondingly, the initial rate of cellobiose hydrolysis by per gram of β-glucosidase adsorbed on hematite (104) face was 1.7 times higher than that on hematite (001) face. However, when the density of hematite particles was same, the extent of cellobiose hydrolysis was 1.2 times higher on hematite (001) face than that on the (104) face, because of the higher adsorbed amount of β-glucosidase on the former. This study decoupled the effects of mineral surface properties on adsorption kinetics and conformational changes of soil enzymes bound to soil minerals and provided new insights into the correlation between mineral surface properties and catalytical activity of mineral-associated enzymes in soil environments.

Vertically aligned NiS2/CoS2/MoS2 nanosheet array as an efficient and low-cost electrocatalyst for hydrogen evolution reaction in alkaline media

Recently, the rational design of non-precious metal electrocatalysts for highly efficient hydrogen evolution reaction (HER) in alkaline media has received considerable interests in sustainable and renewable energy researches. Herein, vertically aligned and interconnected NiS₂/CoS₂/MoS₂ nanosheet arrays on Ni foam were prepared by a two-step procedure that conducted by the hydrothermal synthesis of Ni-Co molybdate nanosheet array as the precursor and followed by the vapor phase sulfurization to achieve in situ conversion. Basing on the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations, it can be found that the honeycomb-like structure of the Ni-Co molybdate nanosheet array was well preserved after the sulfurization process. The high-resolution TEM (HRTEM) characterization reveals that the NiS₂/CoS₂/MoS₂ nanosheet array provided abundant well-exposed active edge sites and multiple heterointerfaces towards enhanced alkaline HER performance. Electrochemical studies demonstrated that the ultrathin NiS₂/CoS₂/MoS₂ nanosheets exhibited excellent HER performance with an overpotential of 112 mV at 10 mA cm^-2 and a smaller Tafel slope of 59 mV dec^-1 in comparison with NiS₂/MoS₂ (155 mV and 89 mV dec^-1) and CoS₂/MoS₂ (124 mV and 75 mV dec^-1) samples by taking the advantage of the well-exposed multiple heterointerfaces. This work presents a facile and reliable synthetic strategy for the rational design of highly efficient electrocatalysts for the HER in alkaline solution based on non-precious metal sulfide nanocomposite.

Rationale for the advancement of PI3K pathway inhibitors for personalized chordoma therapy

PURPOSE

Chordomas are rare and serious tumors with few effective treatments outside of aggressive surgery and radiation. Targeted therapies may present a more effective option for a subset of patients with lesions possessing certain genetic biomarkers.

METHODS

A small molecule inhibitor library was tested in patient-derived UM-Chor1 cells to identify targeted therapies with potential efficacy. Targeted exome sequencing of UM-Chor1 and UM-Chor2 cells was performed to investigate genetic aberrations in relevant pathways. Chordoma cell lines were treated with inhibitors of the phosphotidylinositol 3-kinase (PI3K), epidermal growth factor receptor (EGFR), and cyclin dependent kinase (CDK) pathways, and responses were determined using resazurin cell viability assays, Annexin V apoptosis assays, and western blotting. Pan-PI3K inhibitor BKM120 was also tested in five chordoma xenograft models.

RESULTS

Unbiased small molecule profiling nominated PI3K-AKT-mTOR pathway inhibitors as a promising therapy in chordoma, and genetic analyses of UM-Chor1 and UM-Chor2 cell lines revealed aberrations in PTEN, EGFR, and CDKN2A. Treatment of UM-Chor1 and UM-Chor2 with targeted PI3K, EGFR, and CDK inhibitors inhibited growth and proliferation and induced apoptosis more robustly than imatinib, a currently used chordoma therapy. Furthermore, BKM120 significantly inhibited tumor growth in a subset of the xenograft models tested.

CONCLUSION

Targeted therapies, especially those inhibiting PI3K, display promising effects in multiple chordoma cell line and xenograft models. Nevertheless, the limited effects of PI3K, EGFR, and CDK targeting agents in other models reveal the presence of resistance mechanisms, which motivates future research to both identify biomarkers of response and develop combination therapies.

[Diagnostic value of optical imaging combined with indocyanine green-guided sentinel lymph node biopsy in gastric cancer: a meta-analysis]

Objective: To systematically evaluate the diagnostic value of optical imaging combined with indocyanine green (ICG)-guided sentinel lymph node (SLN) biopsy in gastric cancer, and to identify potential factors that would influence diagnostic accuracy. Methods: Study was carried out by searching the electronic database of PubMed, Embase, Medline, Web of Science, and the Cochrane Library with keywords as "gastric/stomach" and "cancer/carcinoma/tumor/tumour/adenocarcinoma/neoplasm" and "sentinel lymph node" and "near-infrared/NIR or fluorescent imaging" and "indocyanine green/ICG" . Literature inclusion criteria: (1) gastric cancer clinical stage was cT0-3; (2) clinical stage determined by at least 2 kinds of imaging modalities; (3) optical imaging (near-infrared or fluorescence imaging) combined with ICG-guided SLN biopsy; (4) prospective study to predict lymph node metastasis; (5) intraoperative or postoperative pathology for all lymph nodes removed; (6) patients number in the literature >10 cases. Exclusion criteria: (1) patients with a history of ICG allergy or chemoradiotherapy; (2) previous history of endoscopic mucosal resection or endoscopic submucosal dissection; (3) patients with a variety of gastrointestinal tumor; (4) case reports, conference abstracts, clinical guidelines, editorials, reviews, meta-analysis and correspondence letters; (5) in vitro or animal experiments; (6) insufficient diagnostic efficacy data. The meta-analysis was performed in the Stata12.0 software using the "bivariate mixed-effects model" combined with the "midas" command to pool the data. Information such as true positive value, false positive value, false negative value, and true negative value of each included articles were extracted. The literature quality assessment map was drawn to describe the overall quality of the articles; the heterogeneity analysis was performed with the forest map, with P<0.01 considered as statistical significance; the funnel plot was used to describe publication bias, with P<0.1 considered as statistically significant. Area under curve (AUC) of summary receiver operator characteristic (SROC) was used to describe the diagnostic accuracy and the AUC closer to 1 indicated higher diagnostic accuracy. If there was heterogeneity (I(2)>50%) among studies, regression analysis and subgroup analysis were performed. P<0.05 was considered as statistically significant. Results: A total of 15 studies (1020 patients) were included. The optical imaging contained near-infrared (NIR) and fluorescent imaging (FI). The diagnostic value of optical imaging combined with ICG-guided SLN biopsy in gastric cancer was as follows: the pooled sensitivity (Sen) was 0.95 (95% CI: 0.82 to 0.99), specificity (Spe) was 1.00 (95% CI: 0.92 to 1.00), positive likelihood ratio (PLR) was 30.39 (95% CI: 9.14 to 101.06), negative likelihood ratio (NLR) was 0.05 (95% CI:0.01 to 0.20), diagnostic odds ratio (DOR) was 225.54 (95% CI: 88.81 to 572.77), AUC was 1.00 (95% CI: 0.99 to 1.00), threshold value was sensitivity=0.95 (95% CI: 0.82 to 0.99) and specificity=1.00 (95% CI: 0.92 to 1.00). Deeks method revealed DOR funnel plot of SLN biopsy was not asymmetrical obviously with significant difference (P=0.01), which indicated remarkable publishing bias. Meta-subgroup analysis showed that compared to FI, NIR imaging had higher sensitivity (0.98 vs. 0.73); compared to 0 minutes, optical imaging performed 20 minutes after ICG injection had higher sensitivity (0.98 vs. 0.70); compared to mean detected number of SLN of 4, mean detected number≥4 had higher sensitivity (0.96 vs. 0.68); compared to HE stain, immunohistochemistry + HE had higher sensitivity (0.99 vs. 0.84); compared to subserous injection of ICG, submucosa injection of ICG had higher sensitivity (0.98 vs. 0.40); compared to injection of 5 g/L ICG, 0.5 g/L and 0.05 g/L had higher sensitivity (0.98 vs. 0.83); compared to cT2-3 tumor, early stage (cT1) tumor had higher sensitivity (0.96 vs. 0.72); compared to ≤ enrolled 26 cases in the study, > 26 cases had higher sensitivity (0.96 vs. 0.65); compared to papers before 2010, papers after 2010 had higher sensitivity (0.97 vs. 0.81); whose differences were all significant. Sensitivity differences between mean tumor diameter of ≤30 cm and >30 cm, open surgery and laparoscopic surgery, lymph node regional dissection and retrieved dissection were not significant (all P>0.05). Conclusions: Optical imaging combined with ICG-guided SLN biopsy is clinically feasible, and especially suitable for early gastric cancer. However, the ICG being used in current studies may be overdosed. Higher sensitivity may be achieved from NIR imaging when compared with FI method.

A flower-like CoS2/MoS2 heteronanosheet array as an active and stable electrocatalyst toward the hydrogen evolution reaction in alkaline media

CoS₂/MoS₂ heteronanosheet arrays (HNSAs) with vertically aligned flower-like architectures are fabricated through in situ topotactic sulfurization of CoMoO₄ nanosheet array (NSA) precursors on conductive Ni foam. CoMoO₄ NSAs are prepared by a self-template hydrothermal method without using any hard template and surfactant. Benefiting from a 3D flower-like architecture constituted by ultrathin nanosheets with abundant exposed heterointerfaces as highly active sites and predesigned void spaces, the as-synthesized CoS₂/MoS₂ HNSAs exhibit an excellent hydrogen evolution reaction (HER) performance with a low overpotential of 50 mV at 10 mA cm⁻², and a small Tafel slope of 76 mV dec⁻¹ in 1.0 M KOH, which outperforms most previously reported CoS₂ and MoS₂ based electrocatalysts with compositional or morphological similarity. This work demonstrates the great potential in developing high-efficiency and earth-abundant electrocatalysts for alkaline HER through heterointerface engineering and morphological design by utilizing transition metal molybdate as a promising platform.

CoS₂/MoS₂ heteronanosheet arrays with vertically aligned flower-like architecture are fabricated through in situ topotactic sulfurization of CoMoO₄ nanosheet arrays.

Nitrogen-Doped Porous Carbon Nanosheets Strongly Coupled with Mo2C Nanoparticles for Efficient Electrocatalytic Hydrogen Evolution

Exploring earth-abundant and noble metal-free catalysts for water electrolysis is pivotal in renewable hydrogen production. Herein, a highly active electrocatalyst of nitrogen-doped porous carbon nanosheets coupled with Mo₂C nanoparticles (Mo₂C/NPC) was synthesized by a novel method with high BET surface area of 1380 m² g^-1 using KOH to activate carbon composite materials. The KOH plays a key role in etching out MoS₂ to produce Mo precursor; simultaneously, it corrodes carbon to form porous structure and produce reducing gas such as H₂ and CO. The resulting Mo₂C/NPC hybrid demonstrated superior HER activity in acid solution, with the overpotential of 166 mV at current density of 10 mA cm^-2, onset overpotential of 93 mV, Tafel slope of 68 mV dec^-1, and remarkable long-term cycling stability. The present strategy may provide a promising strategy to fabricate other metal carbide/carbon hybrids for energy conversion and storage.

P6499Genetic screening in 109 adult Chinese patients with thoracic aortic aneurysm and dissection

Background

Thoracic aortic aneurysm and dissection (TAAD) comprises a heterogenous group of cardiovascular urgencies, which could be further categorized into syndromic and non-syndromic entities. The accurate and timely identification of culprit genetic variants is of grave importance for TAAD patients, since different genetic defects have been associated with different risks for aortic dissection, thus different thresholds for preventive aortic intervention.

Purpose

With the advent of next-generation sequencing (NGS) techniques, accumulating records of rare variants have been found in TAAD patients, while inadequate functional validation also makes it difficult to give proper counsel for individual TAAD patients. Therefore, it is necessary for us to start re-evaluating clinical applications of genetic screening strategies in specific patient populations.

Methods

From June 2016 to July 2017, genetic screening using an NGS-based panel of 18 candidate genes (FBN1, FBN2, TGFBR1, TGFBR2, TGFB2, TGFB3, SMAD3, COL1A1, COL3A1, COL5A2, COL5A1, PLOD1, ACTA2, MYH11, MYLK, PRKG1, MFAP5, and SKI) was applied in 109 adult TAAD patients from our institution. Patients with bicuspid aortic valve disease, complex congenital cardiac defect, aortic root infection, aortitis, pregnancy, and an age older than 70 years were excluded from the present study.

Results

Among 109 TAAD patients, 36 harboured an FBN1 variant, including 2 splicing site, 6 frame shift, 5 non-sense, and 23 mis-sense variants. The pathogenicity of mis-sense variants was further categorized into 10 disease-causing variants via database survey, 5 disease-causing variants via family survey, and 8 variants of uncertain significance (VUS). On the other hand, 25 patients harboured a non-FBN1 variant, including 3 established pathogenic variants on TGFBR1, TGFB2, and ACTA2 genes, as well as 22 VUS. Patients with an FBN1 variant displayed younger age, lower rate of hypertension, higher rate of aortic root aneurysm, and more frequent mitral valve prolapse, while an extreme male predominance (24/25) was observed in patients with a non-FBN1 variant.

Conclusion

In an adult Chinese TAAD cohort, disease-causing genetic variants were found in 28.4% (31/109) of patients, with FBN1 mutations still being the single leading cause of disease. The present study advocated a genetic screening strategy emphasizing the detection of FBN1 mutations in adult Chinese TAAD patients, and further studies should address the pathogenicity and clinical relevance of non-FBN1 VUS in TAAD patients.

Piezotronics and Piezo-phototronics of Third Generation Semiconductor Nanowires

With the fast development of nanoscience and nanotechnology in the last 30 years, semiconductor nanowires have been widely investigated in the areas of both electronics and optoelectronics. Among them, representatives of third generation semiconductors, such as ZnO and GaN, have relatively large spontaneous polarization along their longitudinal direction of the nanowires due to the asymmetric structure in their c-axis direction. Two-way or multiway couplings of piezoelectric, photoexcitation, and semiconductor properties have generated new research areas, such as piezotronics and piezo-phototronics. In this review, an in-depth discussion of the mechanisms and applications of nanowire-based piezotronics and piezo-phototronics is presented. Research on piezotronics and piezo-phototronics has drawn much attention since the effective manipulation of carrier transport, photoelectric properties, etc. through the application of simple mechanical stimuli and, conversely, since the design of new strain sensors based on the strain-induced change in semiconductor properties.

Risk factors and a predictive nomogram for non-sentinel lymph node metastases in Chinese breast cancer patients with one or two sentinel lymph node macrometastases and mastectomy

Background

Two ongoing prospective randomized trials are evaluating whether omitting axillary lymph node dissection (alnd) in patients with breast cancer (bca) and sentinel lymph node (sln) macrometastases undergoing mastectomy is safe. Determining predictive risk factors for non-sln metastases and developing a model to predict the probability of those patients having non-sln metastases is also important.

Methods

This retrospective study enrolled 396 patients with bca and 1-2 slns with macrometastases who underwent alnd and mastectomy between January 2012 and December 2016. Factors influencing the non-sln metastases were determined, and a predictive nomogram was formulated. Performance of the nomogram was evaluated by its area under the curve (auc).

Results

We developed a predictive nomogram with an auc of 0.81 (cross-validation 95% confidence interval: 0.75 to 0.86) that included 4 factors (tumour size, histologic grade, and number of negative slns and axillary lymph nodes on imaging).

Conclusions

Our predictive nomogram assesses the risk of non-sln metastases in patients with bca and 1-2 sln macrometastases undergoing mastectomy.

Enhanced NO2 gas sensing of a single-layer MoS2 by photogating and piezo-phototronic effects

NO₂ sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However, traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here, we report a simply and reliable flexible NO₂ sensor based on single-layer MoS₂. The flexible sensor exhibits high sensitivity to NO₂ gas due to ultra-large specific surface area and the nature of two-dimensional (2D) semiconductor. When the NO₂ is 400 ppb (parts per billion), compared with the dark and strain-free conditions, the sensitivity of the single-layer sensor is enhanced to 671% with a 625 nm red light-emitting diode (LED) illumination of 4 mW/cm² power under 0.67% tensile strain. More important, the response time is dramatically reduced to ∼16 s and it only needs ∼65 s to complete 90% recovery. A theoretical model is proposed to discuss the microscopic mechanisms. We find that the remarkable sensing characteristics are the result of coupling among piezoelectricity, photoelectricity and adsorption-desorption induced charges transfer in the single-layer MoS₂ Schottky junction based device. Our work opens up the way to further enhancements in the sensitivity of gas sensor based on single-layer MoS₂ by introducing photogating and piezo-phototronic effects in mesoscopic systems.

[A meta-analysis of prognosis after bipolar umbilical cord coagulation or radiofrequency ablation to reduce complicated monochorionic multiple pregnancies]

Objective: To evaluate the prognosis and complications after reduction of monochorionic multifetal pregnancies using bipolar umbilical cord coagulation (BCC) or radiofrequency ablation (RFA). Methods: A literature search were performed by using online databases including PubMed, Embase, and COCHRANE.The publications that described prognosis and complications after selective reduction of monochorionic twin pregnancies using either BCC or RFA for studies with clear outcome data were identified. Results: We identified five retrospective cohort studies for the meta-analysis and 231 cases of BCC and 174 cases of RFA.There was no statistical difference in overall survival after reduction between BCC group (79.2%) and RFA groups (76.4%) (RR=0.96; 95%CI: 0.86~1.08; P=0.48). Neonatal mortality was similar in both groups (8.2% vs 11.1%, respectively; RR=1.34; 95%CI: 0.60~2.99; P=0.48). However, intrauterine fetal death (IUFD) in the RFA group was 13.6%, and it significantly higher than that in the BCC group 7.7% (RR=2.15; 95%CI: 1.10~4.21; P=0.03). In contrast, after reduction, those in the RFA group had less preterm premature rupture of membranes (PPROM) compared with the BCC group (17.1% vs 27.5%, RR=0.58; 95%CI: 0.39~0.86; P=0.007). Conclusions: RFA and BCC groups have similar overall survival for complicated monochromic multiple pregnancies, but RFA was more prone to IUFD, and BCC tended to have more PPROM.Thus, procedures should be chosen according to specific clinical situations and pregnancy conditions.

Design of Bionic Cochlear Basilar Membrane Acoustic Sensor for Frequency Selectivity Based on Film Triboelectric Nanogenerator

Sensorineural hearing loss tops the list of most suffering disease for the sake of its chronic, spirit pressing, and handicapped features, which can happen to all age groups, from newborns to old folks. Laggard technical design as well as external power dependence of conventional cochlear implant cumbers agonized patients and restrict its wider practical application, driving researchers to seek for fundamental improvement. In this paper, we successfully proposed a novel bionic cochlear basilar membrane acoustic sensor in conjugation with triboelectric nanogenerator. By trapezoidally distributing nine silver electrodes on both two polytetrafluoroethylene membranes, a highly frequency-selective function was fulfilled in this gadget, ranging from 20 to 3000 Hz. It is believed to be more discernable with the increment of electrode numbers, referring to the actual basilar membrane in the cochlear. Besides, the as-made device can be somewhat self-powered via absorption of vibration energy carried by sound, which tremendously facilitates its potential users. As a consequence, the elaborate bionic system provides an innovative perspective tackling the problem of sensorineural hearing loss.

Self-powered electrochromic devices with tunable infrared intensity

Triboelectric nanogenerator (TENG) is an efficient way to convert ambient mechanical energy into electricity to power up portable electronics. In this work, a flexible infrared electrochromical device (IR-ECD) with stable performances was assembled with a TENG for building self-powered infrared detector with tunable intensity. As driven by TENG, the electrochromic device could be operated in the mid-IR region due to the reversible electrochromic reactions. An average infrared reflectance contrast of 46% was achieved in 8-14 μm regions and as well a clear thermal image change can be observed. This work indicates that the TENG-driven infrared electrochromical device has potential for use in self-powered camouflage and thermal control.

Self-Healable, Stretchable, Transparent Triboelectric Nanogenerators as Soft Power Sources

Despite the rapid advancements of soft electronics, developing compatible energy devices will be the next challenge for their viable applications. Here, we report an energy-harnessing triboelectric nanogenerator (TENG) as a soft electrical power source, which is simultaneously self-healable, stretchable, and transparent. The nanogenerator features a thin-film configuration with buckled Ag nanowires/poly(3,4-ethylenedioxythiophene) composite electrode sandwiched in room-temperature self-healable poly(dimethylsiloxane) (PDMS) elastomers. Dynamic imine bonds are introduced in PDMS networks for repairing mechanical damages (94% efficiency), while the mechanical recovery of the elastomer is imparted to the buckled electrode for electrical healing. By adjusting the buckling wavelength of the electrode, the stretchability and transparency of the soft TENG can be tuned. A TENG (∼50% stretchabitliy, ∼73% transmittance) can recover the electricity genearation (100% healing efficiency) even after accidental cutting. Finally, the conversion of biomechanical energies into electricity (∼100 V, 327 mW/m²) is demonstrated by a skin-like soft TENG. Considering all these merits, this work suggests a potentially promising approach for next-generation soft power sources.

Piezotronic Effect Enhanced Flexible Humidity Sensing of Monolayer MoS2

We report the piezotronic effect on the performance of humidity detection based on a back-to-back Schottky contacted monolayer MoS₂ device. By introducing an upswept mechanical strain, the in-plane electrical polarization can be induced at the MoS₂/metal junction region. The polarization charges can modify the Schottky barrier height at the interface of MoS₂/metal junction, subsequently improving the sensitivity of the humidity sensing. An energy band diagram is proposed to explain the experiment phenomenon of the humidity sensor. This work provides a simple way to enhance the sensitivity of ultrathin two-dimensional-materials-based sensors by the piezotronic effect, which has great potential applications in electronic skin, human-computer interfacing, gas sensing, and environment monitoring.

Magnetic-Induced-Piezopotential Gated MoS2 Field-Effect Transistor at Room Temperature

Utilizing magnetic field directly modulating/turning the charge carrier transport behavior of field-effect transistor (FET) at ambient conditions is an enormous challenge in the field of micro-nanoelectronics. Here, a new type of magnetic-induced-piezopotential gated field-effect-transistor (MIPG-FET) base on laminate composites is proposed, which consists of Terfenol-D, a ferroelectric single crystal (PMNPT), and MoS₂ flake. When applying an external magnetic field to the MIPG-FET, the piezopotential of PMNPT triggered by magnetostriction of the Terfenol-D can serve as the gate voltage to effectively modulate/control the carrier transport process and the corresponding drain current at room temperature. Considering the two polarization states of PMNPT, the drain current is diminished from 9.56 to 2.9 µA in the P_up state under a magnetic field of 33 mT, and increases from 1.41 to 4.93 µA in the P_down state under a magnetic field of 42 mT and at a drain voltage of 3 V. The current on/off ratios in these states are 330% and 432%, respectively. This work provides a novel noncontact coupling method among magnetism, piezoelectricity, and semiconductor properties, which may have extremely important applications in magnetic sensors, memory and logic devices, micro-electromechanical systems, and human-machine interfacing.