Local modulation of Au/MoS2 Schottky barriers using a top ZnO nanowire gate for high-performance photodetection.

Schottky junctions are commonly used for fabricating heterojunction-based 2D transition metal dichalcogenide (TMD) photodetectors, characteristically offering a wide detection range, high sensitivity and fast response. However, these devices often suffer from reduced detectivity due to the high dark current, making it challenging to discover a simple and efficient universal way to improve the photoelectric performances. Here, we demonstrate a novel approach for integrating ZnO nanowire gates into a MoS2-Au Schottky junction to improve the photoelectric performances of photodetectors by locally controlling the Schottky barrier. This strategy remarkably reduces the dark current level of the device without affecting its photocurrent and the Schottky detectivity can be modified to a maximum detectivity of 1.4 × 1013 Jones with -20 V NG bias. This work provides potential possibilities for tuning the band structure of other materials and optimizing the performance of heterojunction photodetectors.

Artificial Intelligence Meets Flexible Sensors: Emerging Smart Flexible Sensing Systems Driven by Machine Learning and Artificial Synapses.

The recent wave of the artificial intelligence (AI) revolution has aroused unprecedented interest in the intelligentialize of human society. As an essential component that bridges the physical world and digital signals, flexible sensors are evolving from a single sensing element to a smarter system, which is capable of highly efficient acquisition, analysis, and even perception of vast, multifaceted data. While challenging from a manual perspective, the development of intelligent flexible sensing has been remarkably facilitated owing to the rapid advances of brain-inspired AI innovations from both the algorithm (machine learning) and the framework (artificial synapses) level. This review presents the recent progress of the emerging AI-driven, intelligent flexible sensing systems. The basic concept of machine learning and artificial synapses are introduced. The new enabling features induced by the fusion of AI and flexible sensing are comprehensively reviewed, which significantly advances the applications such as flexible sensory systems, soft/humanoid robotics, and human activity monitoring. As two of the most profound innovations in the twenty-first century, the deep incorporation of flexible sensing and AI technology holds tremendous potential for creating a smarter world for human beings.

Switching ultra-stretchability and sensitivity in metal films for electronic skins: a pufferfish-inspired, interlayer regulation strategy.

The booming development of electronic skins necessitates stretchable electrodes and flexible sensors that exhibit distinctly opposite requirements of electromechanical properties, both of which are difficult to be fulfilled on a single material. Here, a pufferfish-inspired, interlayer regulation strategy is proposed that realizes the above opposite properties in simple metal films, exhibiting either ultra-stretchability (295% strain) or sensitivity (maximum GF: ∼5500) on demand. It is revealed that the stretchability of the intrinsically strain-sensitive metal films can be improved by ∼20-fold via regulating the surface morphology of the inserted interlayer, accompanied by an intriguing transition in film cracking behavior from cut-through cracks to network patterns. By featuring these two antithetical but valuable properties, common metal films can be applied as diverse sensors and stretchable electrodes in electronic skins, showing application prospects in healthcare monitoring, human-machine interaction, and engineering services. Our proposed strategy substantially advances the application of metal film conductors in flexible electronics and broadens the horizons for developing more sophisticated electronic skins by interlayer engineering.

Locally Thinned, Core-Shell Nanowire-Integrated Multi-gate MoS2 Transistors for Active Control of Extendable Logic.

Field-effect transistor (FET) devices with multi-gate coupled structures usually exhibit special electrical properties and are suitable for fabricating multifunctional devices. Among them, the 1D nanowire gate configuration has become a promising gate design to tailor 2D FET performances. However, due to possible short circuiting induced by nanowire contact and the high requirement for precision manipulation, the integration of multi-nanowires as gates in a single 2D electronic system remains a grand challenge. Herein, local laser--thinned multiple core-shell SiC@SiO2 nanowires are successfully integrated into MoS2 transistors as multi-gates for active control of extendable logic applications. Nanowire gates (NGs) locally enhance the carrier transportation, and the use of multiple NGs can achieve designed band structures to tune the performance of the device. For core-shell structures, a semiconducting core is used to introduce a gate bias, and the insulating shell provides protection against short circuiting between NGs, facilitating nanowire assembly. Furthermore, a global control gate is introduced to co-tune the overall electrical characteristics, while active control of logic devices and extendable inputs are achieved based on this model. This work proposes a novel nanowire multi-gate configuration, which provides possibilities for localized, precise control of band structures and the fabrication of highly integrated, multifunctional, and controllable nano-devices.

Venation-Mimicking, Ultrastretchable, Room-Temperature-Attachable Metal Tapes for Integrated Electronic Skins.

Future electronic skin systems require stretchable conductors and low-temperature integration of external components, which remains challenging for traditional metal films. Herein, a bioinspired design concept is reported to endow metal films with 200% stretchability as well as room-temperature integration capability with diverse components. It is revealed that by controllable implantation of defects, distinctive venation-mimicking cracking modes can be induced in strained metal films, leading to profound stretchability regulation. An intriguing exponential-to-linear transition of the film electromechanical performance is observed, which is elucidated by a unified model covering the essence of all modes. Combined with room-temperature integration capability, an integrated electronic skin is constructed with metal films serving as stretchable electrodes, diverse sensors, and "tapes" to attach subcomponents, showing prospects in helping disabled people. This one-step, defect implantation strategy is applicable to common metals without special substrate treatments, which enables fascinating ultrastretchable metal film conductors with low-temperature integration capability to spark more sophisticated flexible electronic systems.

High performance 1D-2D CuO/MoS2 photodetectors enhanced by femtosecond laser-induced contact engineering.

The integration of 2D materials with other dimensional materials opens up rich possibilities for both fundamental physics and exotic nanodevices. However, current mixed-dimensional heterostructures often suffer from interfacial contact issues and environment-induced degradation, which severely limits their performance in electronics/optoelectronics. Herein, we demonstrate a novel BN-encapsulated CuO/MoS2 2D-1D van der Waals heterostructure photodetector with an ultrahigh photoresponsivity which is 10-fold higher than its previous 2D-1D counterparts. The interfacial contact state and photodetection capabilities of 2D-1D heterojunctions are significantly improved via femtosecond laser irradiation induced MoS2 wrapping and contamination removal. These h-BN protected devices show highly sensitive, gate-tunable and robust photoelectronic properties. By controlling the gate and bias voltages, the device can achieve a photoresponsivity as high as 2500 A W-1 in the forward bias mode, or achieve a high detectivity of 6.5 × 1011 Jones and a typical rise time of 2.5 ms at reverse bias. Moreover, h-BN encapsulation effectively protects the mixed-dimensional photodetector from electrical depletion by gas molecules such as O2 and H2O during fs laser treatment or the operation process, thus greatly improving the stability and service life in harsh environments. This work provides a new way for the further development of high performance, low cost, and robust mixed-dimensional heterostructure photodetectors by femtosecond laser contact engineering.

Femtosecond Laser Irradiation-Mediated MoS2-Metal Contact Engineering for High-Performance Field-Effect Transistors and Photodetectors.

2D materials exhibit intriguing electrical and optical properties, making them promising candidates for next-generation nanoelectronic devices. However, the high contact resistance of 2D materials to electrode material often limits the ultimate performance and potential of 2D materials and devices. In this work, we demonstrate a localized femtosecond (fs) laser irradiation process to substantially minimize the resistance of MoS2-metal contacts. A reduction of the contact resistance exceeding three orders of magnitude is achieved for mechanically exfoliated MoS2, which remarkably improves the overall FET performance. The underlying mechanisms of resistance reduction are the removal of organic contamination induced by the transfer process, as well as the lowering of Schottky barrier resistance (RSB) attributed to interface Fermi level pinning (FLP) by Au diffusion, and the lowering of interlayer resistance (Rint) due to interlayer coupling enhancement by Au intercalation under fs laser irradiation. By taking advantage of the improved MoS2-metal contact behavior, a high-performance MoS2 photodetector was developed with a photoresponsivity of 68.8 A W-1 at quite a low Vds of 0.5 V, which is ∼80 times higher than the pristine multilayer photodetector. This contamination-free, site-specific, and universal photonic fabrication technique provides an effective tool for the integration of complex 2D devices, and the mechanism of MoS2-metal interface modification reveals a new pathway to engineer the 2D material-metal interface.

Contact engineering of single core/shell SiC/SiO2 nanowire memory unit with high current tolerance using focused femtosecond laser irradiation.

Single nanowire memory units are of particular interest in the design of high-density nanoelectronic circuits, but the performance due to weak contact state remains a major problem. In this paper, bonding between core/shell SiC/SiO2 nanowire and Au electrodes can be improved via local contact engineering with femtosecond (fs) laser irradiation. An optimized heterojunction (Au-SiO2-SiC) is possible since plasmonic enhanced optical absorption can be localized at the metal-oxide (Au-SiO2) interface. Electron transport across the barrier and charge accumulation at the oxide-semiconductor (SiO2-SiC) interface are improved in nanowire circuits. A fast and stable resistance change can be achieved after only one biasing cycle ('write') and the written state can be read/extracted at a low voltage (∼ 0.5 V). Unlike other as-built nanowire circuits, the resistance state can be retained for 10 min in the absence of external power, indicating that these devices can be used for short-term memory units. High current tolerance is also provided in the circuit by the surface oxide shell which acts to protect the inner SiC core. The current density carried by the single SiC/SiO2 nanowire circuit can be as high as ∼3 × 106 A cm-2 before break down, and that breakdown occurs as a two-stage process.

Plasmon-Induced Heterointerface Thinning for Schottky Barrier Modification of Core/Shell SiC/SiO2 Nanowires.

In this work, plasmon-induced heterointerface thinning for Schottky barrier modification of core/shell SiC/SiO2 nanowires is conducted by femtosecond (fs) laser irradiation. The incident energy of polarized fs laser (50 fs, 800 nm) is confined in the SiO2 shell of the nanowire due to strong plasmonic localization in the region of the electrode-nanowire junction. With intense nonlinear absorption in SiO2, the thickness of the SiO2 layer can be thinned in a controllable way. The tuning of the SiO2 barrier layer allows the promotion of electron transportation at the electrode-nanowire interface. The switching voltage of the rectifying junction made by the SiC/SiO2 nanowire can be significantly tuned from 15.7 to 1 V. When selectively thinning at source and drain electrodes and leaving the SiO2 barrier layer at the gate electrode intact, a metal/oxide/semiconductor (MOS) device is fabricated with low leakage current. This optically controlled interfacial engineering technology should be applicable for MOS components and other heterogeneous integration structures.

[Comparison of hand-assisted laparoscopic surgery and open surgery for portal hypertension: a meta-analysis].

OBJECTIVE: To evaluate the clinical efficacy and safety of hand-assisted laparoscopic surgery (HALS) vs. open surgery (OS) for portal hypertension. METHODS: Relevant literature was retrieved from databases including PubMed, EMBASE, Cochrane Library, Chinese Biomedical Literature Database, Chinese Journal Full Text Database, Chinese Vip Datebase, and Chinese Wanfang. All the relevant trials were collected and then we performed the literature screening. The quality of the included trials was assessed by Cochrane Systematic Review Handbook 5.1. Meta-analyses were conducted by RevMan 5.1 software. RESULTS: Eight studies were involved and 435 patients were included. Meta-analysis showed that there was significant difference in intraoperative blood loss [MD = -140.95, 95% CI = (-233.58--48.32), P=0.003], total abdominal drainage volume [MD = -544.32, 95% CI= (-789.97--298.67), P<0.0001], postoperative exhaust time [MD = -28.30, 95% CI= (-41.90--14.69), P<0.0001], length of postoperative hospital stay [MD =-3.61, 95% CI= (-4.16--3.07), P<0.00001], postoperative complication [OR=0.35, 95% CI= (0.15-0.82), P=0.02] between HALS group and OS group. However, the operative time was not significantly different between these two groups [MD = -7.44, 95% CI = (-36.00 -21.12), P=0.61]. CONCLUSIONS: Compared with the traditional OS, HALS can reduce intraoperative bleeding, postoperative exhaust time, hospitalization time, surgical trauma, and postoperative complications.The patients often recover more quickly from the HALS. However, its long-term effictiveness and safety still needs to be further verified by randomized controlled trials.