Venus Flytrap-Inspired Data-Center-Free Fast-Responsive Soft Robots Enabled by 2D Ni3(HITP)2 MOF and Graphite.

The rapid and responsive capabilities of soft robots in perceiving, assessing, and reacting to environmental stimuli are highly valuable. However, many existing soft robots, designed to mimic humans and other higher animals, often rely on data centers for the modulation of mechanoelectrical transduction and electromechanical actuation. This reliance significantly increases system complexity and time delays. Herein, drawing inspiration from Venus flytraps, a soft robot employing a power modulation strategy is presented for active stimulus reaction, eliminating the need for a data center. This robot achieves mechanoelectrical transduction through Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 (Ni3(HITP)2) metal-organic framework (MOF) with an ultralow time delay (256 ns) and electromechanical actuation via graphite. The Joule heating effect in graphite is effectively modulated by Ni3(HITP)2 before and after the presence of pressure, thus enabling the stimulus reaction of soft robots. As demonstrated, three soft robots are created: low-level edge tongue robots, Venus flytrap robots, and high-level nerve-center-controlled dragonfly robots. This power modulation strategy inspires designs of edge soft robots and high-level robots with a human-like effective fusion of conditioned and unconditioned reflexes.

Optoelectronically navigated nano-kirigami microrotors.

With the rapid development of micro/nanofabrication technologies, the concept of transformable kirigami has been applied for device fabrication in the microscopic world. However, most nano-kirigami structures and devices were typically fabricated or transformed at fixed positions and restricted to limited mechanical motion along a single axis due to their small sizes, which significantly limits their functionalities and applications. Here, we demonstrate the precise shaping and position control of nano-kirigami microrotors. Metallic microrotors with size of ~10 micrometers were deliberately released from the substrates and readily manipulated through the multimode actuation with controllable speed and direction using an advanced optoelectronic tweezers technique. The underlying mechanisms of versatile interactions between the microrotors and electric field are uncovered by theoretical modeling and systematic analysis. This work reports a novel methodology to fabricate and manipulate micro/nanorotors with well-designed and sophisticated kirigami morphologies, providing new solutions for future advanced optoelectronic micro/nanomachinery.

Multi-Functional Actuators Made with Biomass-Based Graphene-Polymer Films for Intelligent Gesture Recognition and Multi-Mode Self-Powered Sensing.

Multi-functional actuation systems involve the mechanical integration of multiple actuation and sensor devices with external energy sources. The intricate combination makes it difficult to meet the requirements of lightweight. Hence, polypyrrole@graphene-bacterial cellulose (PPy@G-BC) films are proposed to construct multi-responsive and bilayer actuators integrated with multi-mode self-powered sensing function. The PPy@G-BC film not only exhibits good photo-thermoelectric (PTE) properties but also possesses good hydrophilicity and high Young's modulus. Thus, the PPy@G-BC films are used as active layers in multi-responsive bilayer actuators integrated with self-powered sensing functions. Here, two types of multi-functional actuators integrated with self-powered sensing functions is designed. One is a light-driven actuator that realizes the self-powered temperature sensing function through the PTE effect. Assisted by a machine learning algorithm, the self-powered bionic hand can realize intelligent gesture recognition with an accuracy rate of 96.8%. The other is humidity-driven actuators integrated a zinc-air battery, which can realize self-powered humidity sensing. Based on the above advantages, these two multi-functional actuators are ingeniously integrated into a single device, which can simultaneously perform self-powered temperature/humidity sensing while grasping objects. The highly integrated design enables the efficient utilization of environmental energy sources and complementary synergistic monitoring of multiple physical properties without increasing system complexity.

Haptic Sensing and Feedback Techniques toward Virtual Reality.

Haptic interactions between human and machines are essential for information acquisition and object manipulation. In virtual reality (VR) system, the haptic sensing device can gather information to construct virtual elements, while the haptic feedback part can transfer feedbacks to human with virtual tactile sensation. Therefore, exploring high-performance haptic sensing and feedback interface imparts closed-loop haptic interaction to VR system. This review summarizes state-of-the-art VR-related haptic sensing and feedback techniques based on the hardware parts. For the haptic sensor, we focus on mechanism scope (piezoresistive, capacitive, piezoelectric, and triboelectric) and introduce force sensor, gesture translation, and touch identification in the functional view. In terms of the haptic feedbacks, methodologies including mechanical, electrical, and elastic actuators are surveyed. In addition, the interactive application of virtual control, immersive entertainment, and medical rehabilitation is also summarized. The challenges of virtual haptic interactions are given including the accuracy, durability, and technical conflicts of the sensing devices, bottlenecks of various feedbacks, as well as the closed-loop interaction system. Besides, the prospects are outlined in artificial intelligence of things, wise information technology of medicine, and multimedia VR areas.

Patterned growth of AgBiS2 nanostructures on arbitrary substrates for broadband and eco-friendly optoelectronic sensing.

The patterning of functional nanomaterials shows a promising path in the advanced fabrication of electronic and optoelectronic devices. Current micropatterning strategies are indispensable for post-etching/liftoff processes that contaminate/damage functional materials. Herein, we developed an innovative, low-temperature, post-liftoff-free, seed-confined fabricating strategy that can tackle this issue, thus achieving designated patterns of flower-shaped AgBiS2 nanostructures at either micro- or macro-scale on arbitrary substrates that are either rigid or flexible. Made of patterned AgBiS2 nanostructures, the photoconductor shows broadband (320 nm-2200 nm), sensitive (Rpeak = 1.56 A W-1), and fast (less than 100 µs) photoresponses. Furthermore, single-pixel raster-scanning and 28 × 12 focal plane array imaging were performed to demonstrate reliable and resolved electrical responses to optical patterns, showcasing the potential of the photoconductor in practical imaging applications. Notably, the patterning process enables strain-releasing micro-structures, which lead to the fabrication of a flexible photodetector with high durability upon over 1000 bending/recovering testing cycles. This study provides a simple, low-temperature, and eco-friendly strategy to address the current challenges in non-aggressive micro-fabrication and arbitrary patterning of semiconductors, which are promising to meet the development of further emerging technologies in scalable and wearable optoelectronic sensors.

Multicolor vision perception of flexible optoelectronic synapse with high sensitivity for skin sunburn warning.

The development of flexible synaptic devices with multicolor signal response is important to exploit advanced artificial visual perception systems. The Sn vacancy-dominant memory and narrow gap characteristics of PEA2SnI4 make it suitable as a functional layer in ultraviolet-visible (UV-Vis) light-stimulated synaptic devices. However, such device tends to have high dark current and poor sensitivity, which is not conducive to subsequent information processing. Here, we proposed a self-powered flexible optoelectronic synapse based on PEA2SnI4 films. By introducing the electron transport layer (ETL), the dark current of the device is decreased by 5 orders of magnitude as compared to the Au/PEA2SnI4/ITO device, and the sensitivity is increased from 10.3% to 99.2% at 1.25 mW cm-2 light illumination (520 nm), indicating the vital role of the introduced ETL in promoting the separation of excitons in the interface and inhibiting the free carrier transfer. On this basis, the optoelectronic synaptic functions with integrated sensing, recognition, and memory features were realized. The array device exhibits UV-Vis light sensitivity and tunable synaptic plasticity, enabling its application for multicolor visual sensing and skin sunburn warning. This work provides an effective strategy for fabricating multicolor intelligent sensors and artificial vision systems, which facilitate the practical application of artificial optoelectronic synapses.

An Ultrasensitive Ti3 C2 Tx MXene-based Soft Contact Lens for Continuous and Nondestructive Intraocular Pressure Monitoring.

Wearable soft contact lens sensors for continuous and nondestructive intraocular pressure (IOP) monitoring are highly desired as glaucoma and postoperative myopia patients grow, especially as the eyestrain crowd increases. Herein, a smart closed-loop system is presented that combines a Ti3 C2 Tx MXene-based soft contact lens (MX-CLS) sensor, wireless data transmission units, display, and warning components to realize continuous and nondestructive IOP monitoring/real-time display. The fabricated MX-CLS device exhibits an extremely high sensitivity of 7.483 mV mmHg-1 , good linearity on silicone eyeballs, excellent stability under long-term pressure-release measurement, sufficient transparency with 67.8% transmittance under visible illumination, and superior biocompatibility with no discomfort when putting the MX-CLS sensor onto the Rabbit eyes. After integrating with the wireless module, users can realize real-time monitoring and warning of IOP via smartphones, the demonstrated MX-CLS device together with the IOP monitoring/display system opens up promising platforms for Ti3 C2 Tx materials as the base for multifunctional contact lens-based sensors and continuous and nondestructive IOP measurement system.

Low-dimensional nanostructures for monolithic 3D-integrated flexible and stretchable electronics.

Flexible/stretchable electronics, which are characterized by their ultrathin design, lightweight structure, and excellent mechanical robustness and conformability, have garnered significant attention due to their unprecedented potential in healthcare, advanced robotics, and human-machine interface technologies. An increasing number of low-dimensional nanostructures with exceptional mechanical, electronic, and/or optical properties are being developed for flexible/stretchable electronics to fulfill the functional and application requirements of information sensing, processing, and interactive loops. Compared to the traditional single-layer format, which has a restricted design space, a monolithic three-dimensional (M3D) integrated device architecture offers greater flexibility and stretchability for electronic devices, achieving a high-level of integration to accommodate the state-of-the-art design targets, such as skin-comfort, miniaturization, and multi-functionality. Low-dimensional nanostructures possess small size, unique characteristics, flexible/elastic adaptability, and effective vertical stacking capability, boosting the advancement of M3D-integrated flexible/stretchable systems. In this review, we provide a summary of the typical low-dimensional nanostructures found in semiconductor, interconnect, and substrate materials, and discuss the design rules of flexible/stretchable devices for intelligent sensing and data processing. Furthermore, artificial sensory systems in 3D integration have been reviewed, highlighting the advancements in flexible/stretchable electronics that are deployed with high-density, energy-efficiency, and multi-functionalities. Finally, we discuss the technical challenges and advanced methodologies involved in the design and optimization of low-dimensional nanostructures, to achieve monolithic 3D-integrated flexible/stretchable multi-sensory systems.

Disentangling the role of environmental filtering and biotic resistance on alien invasions in a reservoir area.

Large-scale water conservancy projects benefit human life but have modified the landscape and provided opportunities for alien plant invasions. Understanding the environmental (e.g., climate), human-related (e.g., population density, proximity to human activities), and biotic (e.g., native plant, community structure) factors driving invasions is essential in the management of alien plants and biodiversity conservation in areas with intense human pressure. To this end, we investigated the spatial patterns of alien plant species distribution in the Three Gorges Reservoir Area (TGRA) of China and distinguished the role of the external environment and community characteristics in determining the occurrence of alien plants with differing levels of known invasion impacts in China using random forest analyses and structural equation models. A total of 102 alien plant species belonging to 30 families and 67 genera were recorded, the majority being annual and biennial herbs (65.7%). The results showed a negative diversity-invasibility relationship and supported the biotic resistance hypothesis. Moreover, percentage coverage of native plants was found to interact with native species richness and had a predominant role in resisting alien plant species. We found alien dominance was mainly the result of disturbance (e.g., changes in hydrological regime), which drove native plant loss. Our results also demonstrated that disturbance and temperature were more important for the occurrence of malignant invaders than all alien plants. Overall, our study highlights the importance of restoring diverse and productive native communities in resistance to invasion.

2D Ruddlesden-Popper Sn-Based Perovskite Weak Light Detector for Image Transmission and Reflection Imaging.

2D Ruddlesden-Popper Sn-based perovskite has excellent optoelectronic properties and weak halide ion migration characteristics, making it an ideal candidate for weak light detection, which has great potential in light communication, and medical applications. Although Sn-based perovskite photodetectors are developed, weak light detection is not demonstrated yet. Herein, a high-performance self-powered photodetector with the capability to detect ultra-weak light signals is designed based on vertical PEA2 SnI4 /Si nanowires heterojunction. Due to the low dark current and high light absorption efficiency, the devices present a remarkable responsivity of 42.4 mA W-1 , a high detectivity of 8 × 1011 Jones, and an ultralow noise current of 2.47 × 10-13 A Hz-1/2 . Especially, the device exhibits a high on-off current ratio of 18.6 at light signals as low as 4.60 nW cm-2 , revealing the capacity to detect ultra-weak light. The device is applied as a signal receiver and realized image transmission in light communication system. Moreover, high-resolution reflection imaging and multispectral imaging are obtained using the device as the sensor in the imaging system. These results reveal that 2D PEA2 SnI4 -based self-powered photodetectors with low-noise current possess enormous potential in future weak light detection.

MXene based flexible photodetectors: progress, challenges, and opportunities.

The growing interest in applying 2D transition-metal carbides and nitrides (MXenes) to diverse application fields such as energy storage and harvesters, catalysts, sensors, optoelectronics, electromagnetic interference shielding and antennas since its first discovery in 2011 is clearly evident. Their intrinsic high conductivity limits the development of MXenes in photodetectors that rely on the semiconducting properties of active materials, while the abundant functional groups on the surface of MXenes provide opportunities for using MXenes as sensing materials in the fabrication of flexible photodetectors. Considerable studies on MXene based photodetectors have been carried out, but the main obstacles include seeking novel semiconducting materials in MXene families, the manufacturing technology, etc. This review highlights the progress, challenges and opportunities in MXene based flexible photodetectors and discusses novel materials, architectures, and approaches that capitalize on our growing understanding of MXenes.

Bioinspired Young's Modulus-Hierarchical E-Skin with Decoupling Multimodality and Neuromorphic Encoding Outputs to Biosystems.

As key interfaces for the disabled, optimal prosthetics should elicit natural sensations of skin touch or proprioception, by unambiguously delivering the multimodal signals acquired by the prosthetics to the nervous system, which still remains challenging. Here, a bioinspired temperature-pressure electronic skin with decoupling capability (TPD e-skin), inspired by the high-low modulus hierarchical structure of human skin, is developed to restore such functionality. Due to the bionic dual-state amplifying microstructure and contact resistance modulation, the MXene TPD e-skin exhibits high sensitivity over a wide pressure range and excellent temperature insensitivity (91.2% reduction). Additionally, the high-low modulus structural configuration enables the pressure insensitivity of the thermistor. Furthermore, a neural model is proposed to neutrally code the temperature-pressure signals into three types of nerve-acceptable frequency signals, corresponding to thermoreceptors, slow-adapting receptors, and fast-adapting receptors. Four operational states in the time domain are also distinguished after the neural coding in the frequency domain. Besides, a brain-like machine learning-based fusion process for frequency signals is also constructed to analyze the frequency pattern and achieve object recognition with a high accuracy of 98.7%. The TPD neural system offers promising potential to enable advanced prosthetic devices with the capability of multimodality-decoupling sensing and deep neural integration.

A neuromorphic bionic eye with filter-free color vision using hemispherical perovskite nanowire array retina.

Spherical geometry, adaptive optics, and highly dense network of neurons bridging the eye with the visual cortex, are the primary features of human eyes which enable wide field-of-view (FoV), low aberration, excellent adaptivity, and preprocessing of perceived visual information. Therefore, fabricating spherical artificial eyes has garnered enormous scientific interest. However, fusing color vision, in-device preprocessing and optical adaptivity into spherical artificial eyes has always been a tremendous challenge. Herein, we demonstrate a bionic eye comprising tunable liquid crystal optics, and a hemispherical neuromorphic retina with filter-free color vision, enabled by wavelength dependent bidirectional synaptic photo-response in a metal-oxide nanotube/perovskite nanowire hybrid structure. Moreover, by tuning the color selectivity with bias, the device can reconstruct full color images. This work demonstrates a unique approach to address the color vision and optical adaptivity issues associated with artificial eyes that can bring them to a new level approaching their biological counterparts.

Giant panda-focused conservation has limited value in maintaining biodiversity and carbon sequestration.

Biodiversity and climate are interconnected through carbon. Drivers of climate change and biodiversity loss interact in complex ways to produce outcomes that may be synergistic, and biodiversity loss and climate change reinforce each other. Prioritizing the conservation of flagship and umbrella species is often used as a surrogate strategy for broader conservation goals, but it is unclear whether these efforts truly benefit biodiversity and carbon stocks. Conservation of the giant panda offers a paradigm to test these assumptions. Here, using the benchmark estimates of ecosystem carbon stocks and species richness, we investigated the relationships among the giant panda, biodiversity, and carbon stocks and assessed the implications of giant panda conservation for biodiversity and carbon-focused conservation efforts. We found that giant panda density and species richness were significantly positively correlated, while no correlation was found between giant panda density and soil carbon or total carbon density. The established nature reserves protect 26 % of the giant panda conservation region, but these areas contain <21 % of the ranges of other species and <21 % of total carbon stocks. More seriously, giant panda habitats are still facing high risks of habitat fragmentation. Habitat fragmentation is negatively correlated with giant panda density, species richness, and total carbon density. The ongoing giant panda habitat fragmentation is likely to cause an additional 12.24 Tg C of carbon emissions over 30 years. Thus, giant panda-focused conservation efforts have effectively prevented giant panda extinction but have been less effective in maintaining biodiversity and high­carbon ecosystems. It is urgent for China to contribute to the development of an effective and representative national park system that integrates climate change issues into national biodiversity strategies and vice versa in dealing with the dual environmental challenges of biodiversity loss and climate change under a post-2020 framework.

Air-Stable Flexible Photodetector Based on MXene-Cs3Bi2I9 Microplate Schottky Junctions for Weak-Light Detection.

Weak-light detection technology is widely used in various fields, including industry, high-energy physics, precision analysis, and reflection imaging. Metal-semiconductor-metal (MSM) photodetectors demonstrate high detectivity and high response speed and are one of the suitable structures for the preparation of weak-light detectors. However, traditional MSM photodetectors tend to exhibit high dark currents, which are not conducive to performance improvement. Here, a MXene-Cs3Bi2I9-MXene weak-light detector is proposed. Based on the MXene-Cs3Bi2I9 Schottky junctions, the dark current is reduced by 2 orders of magnitude and the responsivity is significantly improved compared with the traditional Cr/Au-Cs3Bi2I9-Cr/Au MSM photodetector. The device demonstrates excellent photodetection capacity with a photoresponsivity of 6.45 A W-1, a specific detectivity of 9.45 × 1011 Jones, and a fast response speed of 0.27/2.32 ms. Especially, the device yielded a superior weak-light detectable limit of 10.66 nW cm-2 and demonstrated excellent optical communication capability. Moreover, such a flexible device shows little degradation in photodetection performance after extreme bending for 4500 cycles, proving remarkable bending endurance and flexibility. The obtained results highlight the great potential of such Cs3Bi2I9/MXene devices as a stable and environmentally friendly candidate for weak-light detection.

Incorporating Wireless Strategies to Wearable Devices Enabled by a Photocurable Hydrogel for Monitoring Pressure Information.

Advances in emerging technologies for wireless collection and the timely analysis of various information captured by wearable devices are of growing interest. Herein, a crosslinked ionic hydrogel prepared by a facile photocuring process is proposed, which allows wearable devices to be further incorporated into two wireless integrated systems for pressure monitoring applications. The device exhibits a simplified structure by effectively sharing functional layers, rather than conventional two separate combinations, offering the salient performance of iontronic sensing and electrochromic properties to simultaneously quantify and visualize pressure. The developed smart patch system is demonstrated to monitor physiological signals in real-time utilizing the user interface of remote portable equipment with the Bluetooth protocol and on-site electrochromic displays. Moreover, a passive wireless system based on the magnetic coupling effect is designed, which can operate free from the battery and simultaneously acquire multiple pressure information. It is envisioned that the strategies would hold enormous potential for flexible electronics, versatile sensing platforms, and wireless on-body networks.

A Ti3C2Tx MXene cathode and redox-active electrolyte based flexible Zn-ion microsupercapacitor for integrated pressure sensing application.

Frequently used aqueous electrolytes in MXene-based Zn-ion hybrid microsupercapacitors (MSCs) limit their cycling and rate stability. The use of metal and nonmetal additives in electrolytes for the performance improvement of Zn-ion MSCs is considered a valid method. Herein, we propose an additive assisted Zn(CF3SO3)2 electrolyte as a redox-active electrolyte to prepare a flexible MXene-based Zn-ion hybrid MSC by a facile spraying method, and it consists of a conductive Ti3C2Tx-LiCl current collector and a Ti3C2Tx-DMSO cathode. In the process of the current density change (from 5 A cm-3 to 30 A cm-3 and then to 5 A cm-3), the capacity retention of the as-fabricated MSC with K3Co(CN)6 additive is over 99.0%, which is higher than 96.7% for the MSC with CKNSe additive and 82.3% for the MSC without an additive. Moreover, the designed MSC with the redox-active K3Co(CN)6 electrolyte exhibits a maximal capacitance retention of 70% after 5000 cycles. Furthermore, the flexible Zn-ion MSC with the Ti3C2Tx MXene cathode and a redox-active electrolyte was used to power a Ti3C2Tx based pressure sensor; the excellent press response of the integrated system not only provides insights into the development of large capacity and long-period stable energy storage devices, but also paves a new way for the development of capacitor-sensor integrated systems.

Neuromorphic-computing-based adaptive learning using ion dynamics in flexible energy storage devices.

High-accuracy neuromorphic devices with adaptive weight adjustment are crucial for high-performance computing. However, limited studies have been conducted on achieving selective and linear synaptic weight updates without changing electrical pulses. Herein, we propose high-accuracy and self-adaptive artificial synapses based on tunable and flexible MXene energy storage devices. These synapses can be adjusted adaptively depending on the stored weight value to mitigate time and energy loss resulting from recalculation. The resistance can be used to effectively regulate the accumulation and dissipation of ions in single devices, without changing the external pulse stimulation or preprogramming, to ensure selective and linear synaptic weight updates. The feasibility of the proposed neural network based on the synapses of flexible energy devices was investigated through training and machine learning. The results indicated that the device achieved a recognition accuracy of ∼95% for various neural network calculation tasks such as numeric classification.

Dual sensing signal decoupling based on tellurium anisotropy for VR interaction and neuro-reflex system application.

Anisotropy control of the electronic structure in inorganic semiconductors is an important step in developing devices endowed with multi-function. Here, we demonstrate that the intrinsic anisotropy of tellurium nanowires can be used to modulate the electronic structure and piezoelectric polarization and decouple pressure and temperature difference signals, and realize VR interaction and neuro-reflex applications. The architecture design of the device combined with self-locking effect can eliminate dependence on displacement, enabling a single device to determine the hardness and thermal conductivity of materials through a simple touch. We used a bimodal Te-based sensor to develop a wearable glove for endowing real objects to the virtual world, which greatly improves VR somatosensory feedback. In addition, we successfully achieved stimulus recognition and neural-reflex in a rabbit sciatic nerve model by integrating the sensor signals using a deep learning technique. In view of in-/ex-vivo feasibility, the bimodal Te-based sensor would be considered a novel sensing platform for a wide range application of metaverse, AI robot, and electronic medicine.