Bistable Insect-Scale Jumpers with Tunable Energy Barriers for Multimodal Locomotion.

Drawing inspiration from the jumping mechanisms of insects (e.g., click beetles), bistable structures can convert slow deformations of soft actuating material into fast jumping motions (i.e., power amplification). However, bistable jumpers often encounter large energy barriers for energy release/re-storage, posing a challenge in achieving multimodal (i.e., height/distance) and continuous jumps at the insect scale (body length under 20 mm). Here, a new offset-buckling bistable design is introduced that features antisymmetric equilibrium states and tunable energy barriers. Leveraging this design, a Boundary Actuation Tunable Energy-barrier (BATE) jumper (body length down to 15 mm) is developed, and transform BATE jumper from height-jump mode (up to 12.7 body lengths) to distance-jump mode (up to 20 body lengths). BATE jumpers can perform agile continuous jumping (within 300 ms for energy release/re-storage times) and real-time status detection is further demonstrated. This insect-level performance of the proposed BATE jumper showcases its potential toward future applications in exploration, search, and rescue.

A mechanically robust and facile shape morphing using tensile-induced buckling.

Inspired by the adaptive mechanisms observed in biological organisms, shape-morphing soft structures have emerged as promising platforms for many applications. In this study, we present a shape-morphing strategy to overcome existing limitations of the intricate fabrication process and the lack of mechanical robustness against mechanical perturbations. Our method uses tensile-induced buckling, achieved by attaching restraining strips to a stretchable substrate. When the substrate is stretched, the stiffness mismatch between the restraining strips and the substrate, and the Poisson's effect on the substrate cause the restraining strips to buckle, thereby transforming initially flat shapes into intricate three-dimensional (3D) configurations. Guided by an inverse design method, we demonstrate the capability to achieve complicated and diverse 3D shapes. Leveraging shape morphing, we further develop soft grippers exhibiting outstanding universality, high grasping efficiencies, and exceptional durability. Our proposed shape-morphing strategy is scalable and material-independent, holding notable potential for applications in soft robotics, haptics, and biomedical devices.

Strong, tough and anisotropic bioinspired hydrogels.

Soft materials are widely used in tissue engineering, soft robots, wearable electronics, etc. However, it remains a challenge to fabricate soft materials, such as hydrogels, with both high strength and toughness that are comparable to biological tissues. Inspired by the anisotropic structure of biological tissues, a novel solvent-exchange-assisted wet-stretching strategy is proposed to prepare anisotropic polyvinyl alcohol (PVA) hydrogels by tuning the macromolecular chain movement and optimizing the polymer network. The reinforcing and toughening mechanisms are found to be "macromolecule crystallization and nanofibril formation". These hydrogels exhibit excellent mechanical properties, such as extremely high fracture stress (12.8 ± 0.7 MPa) and fracture strain (1719 ± 77%), excellent modulus (4.51 ± 0.76 MPa), high work of fracture (134.47 ± 9.29 MJ m-3), and fracture toughness (305.04 kJ m-2) compared with other strong hydrogels and even natural tendons. In addition, excellent conductivity, strain sensing capability, water retention, freezing resistance, swelling resistance, and biocompatibility can also be achieved. This work provides a new and effective method to fabricate multifunctional anisotropic hydrogels with high tunable strength and toughness with potential applications in the fields of regenerative medicine, flexible sensors, and soft robotics.

Mechanical Metamaterials for Handwritten Digits Recognition.

The increasing needs for new types of computing lie in the requirements in harsh environments. In this study, the successful development of a non-electrical neural network is presented that functions based on mechanical computing. By overcoming the challenges of low mechanical signal transmission efficiency and intricate layout design methodologies, a mechanical neural network based on bistable kirigami-based mechanical metamaterials have designed. In preliminary tests, the system exhibits high reliability in recognizing handwritten digits and proves operable in low-temperature environments. This work paves the way for a new, alternative computing system with broad applications in areas where electricity is not accessible. By integrating with the traditional electronic computers, the present system lays the foundation for a more diversified form of computing.

Physics-supervised deep learning-based optimization (PSDLO) with accuracy and efficiency.

Identifying efficient and accurate optimization algorithms is a long-desired goal for the scientific community. At present, a combination of evolutionary and deep-learning methods is widely used for optimization. In this paper, we demonstrate three cases involving different physics and conclude that no matter how accurate a deep-learning model is for a single, specific problem, a simple combination of evolutionary and deep-learning methods cannot achieve the desired optimization because of the intrinsic nature of the evolutionary method. We begin by using a physics-supervised deep-learning optimization algorithm (PSDLO) to supervise the results from the deep-learning model. We then intervene in the evolutionary process to eventually achieve simultaneous accuracy and efficiency. PSDLO is successfully demonstrated using both sufficient and insufficient datasets. PSDLO offers a perspective for solving optimization problems and can tackle complex science and engineering problems having many features. This approach to optimization algorithms holds tremendous potential for application in real-world engineering domains.

Plug & play origami modules with all-purpose deformation modes.

Three basic deformation modes of an object (bending, twisting, and contraction/extension) along with their various combinations and delicate controls lead to diverse locomotion. As a result, seeking mechanisms to achieve simple to complex deformation modes in a controllable manner is a focal point in related engineering fields. Here, a pneumatic-driven, origami-based deformation unit that offers all-purpose deformation modes, namely, three decoupled basic motion types and four combinations of these three basic types, with seven distinct motion modes in total through one origami module, was created and precisely controlled through various pressurization schemes. These all-purpose origami-based modules can be readily assembled as needed, even during operation, which enables plug-and-play characteristics. These origami modules with all-purpose deformation modes offer unprecedented opportunities for soft robots in performing complex tasks, which were successfully demonstrated in this work.

Bioinspired helical-artificial fibrous muscle structured tubular soft actuators.

Biological tubular actuators show diverse deformations, which allow for sophisticated deformations with well-defined degrees of freedom (DOF). Nonetheless, synthetic active tubular soft actuators largely only exhibit few simple deformations with limited and undesignable DOF. Inspired by 3D fibrous architectures of tubular muscular hydrostats, we devised conceptually new helical-artificial fibrous muscle structured tubular soft actuators (HAFMS-TSAs) with locally tunable molecular orientations, materials, mechanics, and actuation via a modular fabrication platform using a programmable filament winding technique. Unprecedentedly, HAFMS-TSAs can be endowed with 11 different morphing modes through programmable regulation of their 3D helical fibrous architectures. We demonstrate a single "living" artificial plant rationally structured by HAFMS-TSAs exhibiting diverse photoresponsive behaviors that enable adaptive omnidirectional reorientation of its hierarchical 3D structures in the response to environmental irradiation, resembling morphing intelligence of living plants in reacting to changing environments. Our methodology would be significantly beneficial for developing sophisticated soft actuators with designable and tunable DOF.

Soft and lightweight fabric enables powerful and high-range pneumatic actuation.

Soft structures and actuation allow robots, conventionally consisting of rigid components, to perform more compliant, adaptive interactions similar to living creatures. Although numerous functions of these types of actuators have been demonstrated in the literature, their hyperelastic designs generally suffer from limited workspaces and load-carrying capabilities primarily due to their structural stretchability factor. Here, we describe a series of pneumatic actuators based on soft but less stretchable fabric that can simultaneously perform tunable workspace and bear a high payload. The motion mode of the actuator is programmable, combinable, and predictable and is informed by rapid response to low input pressure. A robotic gripper using three fabric actuators is also presented. The gripper demonstrates a grasping force of over 150 N and a grasping range from 70 to 350 millimeters. The design concept and comprehensive guidelines presented would provide design and analysis foundations for applying less stretchable yet soft materials in soft robots to further enhance their practicality.

The role of intercellular junction proteins in the penetration resistance of Drosophila larvae to avermectin.

Insecticide resistance has become an increasingly serious challenge for agriculture in the world. To reveal the mechanisms of insecticide resistance, majority of studies have been carried out on the insensitivity of insecticide targets and the metabolism of insecticides. However, the mechanism of the insecticide penetration resistance in insects remains unclear. This study aimed to reveal the mechanism underlying the penetration resistance of Drosophila larvae to insecticide avermectin (AVM). Levels of intercellular junction proteins (IJPs) in the larvae were determined by Western blotting analysis and immunofluorescence assay. The result showed that the expression of IJPs septate junction and adherens junction proteins increased in the AVM-resistant insects compared with those in the AVM-susceptible ones, and the upregulation of the IJPs was mediated by the activation of protein kinase C (PKC) pathway. That AVM induced the activation of PKC was found not only in the Drosophila larvae but also in Drosophila S2 cells. These findings revealed that AVM could activate PKC pathway in Drosophila larvae, which mediated the upregulation of the IJPs and then led to the resistance to AVM, suggesting that the chemicals that can disrupt PKC activation may potentially be used to circumvent the resistance to AVM in insects.

Safety and immunogenicity of a primary series and booster dose of the meningococcal serogroup B-factor H binding protein vaccine (MenB-FHbp) in healthy children aged 1-9 years: two phase 2 randomised, controlled, observer-blinded studies.

BACKGROUND: The meningococcal serogroup B-factor H binding protein vaccine (MenB-FHbp) is licensed for use in children aged 10 years or older for protection against invasive serogroup B meningococcal disease. Because young children are at increased risk of invasive meningococcal disease, MenB-FHbp clinical data in this population are needed. METHODS: We conducted two phase 2 randomised, controlled, observer-blinded studies including healthy toddlers (age 12-23 months) across 26 Australian, Czech, Finnish, and Polish centres, and older children (age 2-9 years) across 14 Finnish and Polish centres. Exclusion criteria included previous vaccinations against serogroup B meningococcus or hepatitis A virus (HAV), and chronic antibiotic use. Toddlers were randomly allocated (2:1) via an interactive response technology system to receive either 60 µg or 120 µg MenB-FHbp or HAV vaccine and saline (control). Older children were randomly allocated (3:1) to receive 120 µg MenB-FHbp or control, with stratification by age group (2-3 years and 4-9 years). All vaccinations were administered as three doses (0, 2, and 6 months, with only saline given at 2 months in the control group). Toddlers who received 120 µg MenB-FHbp could receive a 120 µg booster dose 24 months after the end of the primary series. The percentages of participants with serum bactericidal activity using human complement (hSBA) titres at or above the lower limit of quantification (LLOQ; all greater than the 1:4 correlate of protection) against four test strains of serogroup B meningococcus 1 month after the third dose (primary immunogenicity endpoint) were measured in the evaluable immunogenicity populations (participants who received the vaccine as randomised, had available and determinate hSBA results, and had no major protocol violations). Not all participants were tested against all strains because of serum sample volume constraints. The frequencies of reactogenicity and adverse events after each dose were recorded in the safety population (all participants who received at least one dose and had safety data available). These studies are registered with ClinicalTrials.gov (NCT02534935 and NCT02531698) and are completed. FINDINGS: Between Aug 31, 2015, and Aug 22, 2016, for the toddler study and between Aug 27, 2015, and March 7, 2016, for the older children study, we enrolled and randomly allocated 396 toddlers (60 µg MenB-FHbp group n=44; 120 µg MenB-FHbp group n=220; control group n=132) and 400 older children (120 µg MenB-FHbp group n=294; control group n=106). 1 month after the third dose, the proportions of participants with hSBA titres at or above the LLOQ ranged across test strains from 85·0% (95% CI 62·1-96·8; 17 of 20 participants) to 100·0% (82·4-100·0; 19 of 19) in toddlers receiving 60 µg MenB-FHbp, and from 71·6% (61·4-80·4; 68 of 95) to 100·0% (96·2-100·0; 95 of 95) in toddlers receiving 120 µg MenB-FHbp, and from 79·1% (71·2-85·6; 106 of 134) to 100·0% (97·4-100·0; 139 of 139) in children aged 2-9 years receiving 120 µg MenB-FHbp. hSBA titres peaked at 1 month after the third primary dose of MenB-FHbp and then declined over time. 24 months after the third dose in the toddler study, the proportions with hSBA titres at or above the LLOQ ranged from 0·0% (0·0-17·6; 0 of 19 participants) to 41·2% (18·4-67·1; seven of 17) in those who received 60 µg MenB-FHbp and from 3·7% (0·8-10·4; three of 81) to 22·8% (14·1-33·6; 18 of 79) in those who received 120 µg MenB-FHbp. 1 month after the booster dose in toddlers, the proportions with hSBA titres at or above the LLOQ were higher than at 1 month after the primary series. MenB-FHbp reactogenicity was mostly transient and of mild to moderate severity. Adverse event frequency was similar between the MenB-FHbp and control groups and less frequent following MenB-FHbp booster than following primary doses. Two participants from the toddler study (both from the 120 µg MenB-FHbp group) and four from the older children study (three from the 120 µg MenB-FHbp group and one from the control group) were withdrawn from the study because of adverse events. INTERPRETATION: MenB-FHbp was well tolerated and induced protective immune responses in a high proportion of participants. These findings support a favourable MenB-FHbp immunogenicity and reactogenicity profile in young children, a population at increased risk of adverse invasive meningococcal disease outcomes. FUNDING: Pfizer.

Buckling-induced wavy optical fiber attenuator.

An optical attenuator is an optical device that can modulate the power level of an optical signal. Based on the macro-bending loss of optical fibers, we present a wavy fiber attenuator where the attenuation level can be controlled by a mechanical-induced buckling of the fiber. By bonding a fiber to a prestretched substrate and then releasing the prestrain, the fiber flexes into a sinusoidal wavy curve due to the constraints of the substrate. The level of the light attenuation can simply be controlled by stretching the substrate. The maximum attenuation of the proposed wavy optical fiber attenuator is -87.3 dB.

A film-lever actuated switch technology for multifunctional, on-demand, and robust manipulation of liquids.

A lab-on-a-chip system with Point-of-Care testing capability offers rapid and accurate diagnostic potential and is useful in resource-limited settings where biomedical equipment and skilled professionals are not readily available. However, a Point-of-Care testing system that simultaneously possesses all required features of multifunctional dispensing, on-demand release, robust operations, and capability for long-term reagent storage is still a major challenge. Here, we describe a film-lever actuated switch technology that can manipulate liquids in any direction, provide accurate and proportional release response to the applied pneumatic pressure, as well as sustain robustness during abrupt movements and vibrations. Based on the technology, we also describe development of a polymerase chain reaction system that integrates reagent introduction, mixing and reaction functions all in one process, which accomplishes "sample-in-answer-out" performance for all clinical nasal samples from 18 patients with Influenza and 18 individual controls, in good concordance of fluorescence intensity with standard polymerase chain reaction (Pearson coefficients > 0.9). The proposed platform promises robust automation of biomedical analysis, and thus can accelerate the commercialization of a range of Point-of-Care testing devices.

Rechargeable Metasurfaces for Dynamic Color Display Based on a Compositional and Mechanical Dual-Altered Mechanism.

Dynamic color display can be realized by tunable optical metasurfaces based on the compositional or structural control. However, it is still a challenge to realize the efficient modulation by a single-field method. Here, we report a novel compositional and mechanical dual-altered rechargeable metasurface for reversible and broadband optical reconfiguration in both visible and near-infrared wavelength regions. By employing a simple fabrication and integration strategy, the continuous optical reconfiguration is manipulated through an electro-chemo-mechanical coupled process in a lithium ion battery, where lithiation and delithiation processes occur dynamically under a low electric voltage (≤1.5 V). By controlling the phase transformation from Si to Li xSi, both structural morphology and optical scattering could be rapidly and dramatically tailored within 30 s, exhibiting high-contrast colorization and decolorization in a large-area nanofilm and showing long cyclic stability. Significant wide-angle reconfiguration of high-resolution structural colors in bowtie metasurfaces is demonstrated from anomalous reflection. The results provide a multifield mechanism for reconfigurable photonic devices, and the new platform can be introduced to the multidimensional information encryption and storage.

Mobile3DScanner: An Online 3D Scanner for High-quality Object Reconstruction with a Mobile Device.

We present a novel online 3D scanning system for high-quality object reconstruction with a mobile device, called Mobile3DScanner. Using a mobile device equipped with an embedded RGBD camera, our system provides online 3D object reconstruction capability for users to acquire high-quality textured 3D object models. Starting with a simultaneous pose tracking and TSDF fusion module, our system allows users to scan an object with a mobile device to get a 3D model for real-time preview. After the real-time scanning process is completed, the scanned 3D model is globally optimized and mapped with multi-view textures as an efficient postprocess to get the final textured 3D model on the mobile device. Unlike most existing state-of-the-art systems which can only scan homeware objects such as toys with small dimensions due to the limited computation and memory resources of mobile platforms, our system can reconstruct objects with large dimensions such as statues. We propose a novel visual-inertial ICP approach to achieve real-time accurate 6DoF pose tracking of each incoming frame on the front end, while maintaining a keyframe pool on the back end where the keyframe poses are optimized by local BA. Simultaneously, the keyframe depth maps are fused by the optimized poses to a TSDF model in real-time. Especially, we propose a novel adaptive voxel resizing strategy to solve the out-of-memory problem of large dimension TSDF fusion on mobile platforms. In the post-process, the keyframe poses are globally optimized and the keyframe depth maps are optimized and fused to obtain a final object model with more accurate geometry. The experiments with quantitative and qualitative evaluation demonstrate the effectiveness of the proposed 3D scanning system based on a mobile device, which can successfully achieve online high-quality 3D reconstruction of natural objects with larger dimensions for efficient AR content creation.

Persistence of hSBA titers elicited by the meningococcal serogroup B vaccine menB-FHbp for up to 4 years after a 2- or 3-dose primary series and immunogenicity, safety, and tolerability of a booster dose through 26 months.

BACKGROUND: To demonstrate extended protection against meningococcal serogroup B (MenB) disease after MenB-FHbp (bivalent rLP2086) vaccination, this study evaluated immunopersistence through 26 months following MenB-FHbp boosting after 2 or 3 primary doses in adolescents. STUDY DESIGN: This phase 3, open-label study was an extension of 3 phase 2 studies with participants aged 11-18 years randomized to receive primary MenB-FHbp vaccination following 1 of 5 dosing schedules or control. A booster dose was administered 48 months after the primary series. Immunopersistence through 48 months after the last primary dose (persistence stage) and 26 months postbooster (booster stage) was determined by serum bactericidal assays using human complement (hSBAs) against 4 vaccine-heterologous test strains. Safety evaluations included adverse events (AEs) and local and systemic reactions. RESULTS: Overall, 698 and 304 subjects enrolled in the persistence and booster stages, respectively. hSBA titers declined in all groups during 12 months postprimary vaccination, then remained stable through 48 months. One month postbooster, 93.4-100.0% of subjects achieved hSBA titers ≥ lower limit of quantitation against each test strain; percentages at 12 and 26 months postbooster were higher than at similar time points following primary vaccination. Primary and booster MenB-FHbp vaccinations were well tolerated, with ≤ 12.5% of subjects reporting AEs during each stage. The most common local (reported by 84.4-93.8% of subjects) and systemic (68.8-76.6%) reactions to the booster were injection site pain and fatigue and headache, respectively; ≤ 3.7% of subjects reported severe systemic events. CONCLUSION: Protective hSBA titers initially declined but were retained by many subjects for 4 years irrespective of primary MenB-FHbp vaccination schedule. Boosting at 48 months after primary vaccination was safe, well tolerated, and induced immune responses indicative of immunological memory that persisted through 26 months. Booster vaccination during late adolescence may prolong protection against MenB disease.

In situ stiffness manipulation using elegant curved origami.

The capability of stiffness manipulation for materials and structures is essential for tuning motion, saving energy, and delivering high power. However, high-efficiency in situ stiffness manipulation has not yet been successfully achieved despite many studies from different perspectives. Here, curved origami patterns were designed to accomplish in situ stiffness manipulation covering positive, zero, and negative stiffness by activating predefined creases on one curved origami pattern. This elegant design enables in situ stiffness switching in lightweight and space-saving applications, as demonstrated through three robotic-related components. Under a uniform load, the curved origami can provide universal gripping, controlled force transmissibility, and multistage stiffness response. This work illustrates an unexplored and unprecedented capability of curved origami, which opens new applications in robotics for this particular family of origami patterns.

Mobile3DRecon: Real-time Monocular 3D Reconstruction on a Mobile Phone.

We present a real-time monocular 3D reconstruction system on a mobile phone, called Mobile3DRecon. Using an embedded monocular camera, our system provides an online mesh generation capability on back end together with real-time 6DoF pose tracking on front end for users to achieve realistic AR effects and interactions on mobile phones. Unlike most existing state-of-the-art systems which produce only point cloud based 3D models online or surface mesh offline, we propose a novel online incremental mesh generation approach to achieve fast online dense surface mesh reconstruction to satisfy the demand of real-time AR applications. For each keyframe of 6DoF tracking, we perform a robust monocular depth estimation, with a multi-view semi-global matching method followed by a depth refinement post-processing. The proposed mesh generation module incrementally fuses each estimated keyframe depth map to an online dense surface mesh, which is useful for achieving realistic AR effects such as occlusions and collisions. We verify our real-time reconstruction results on two mid-range mobile platforms. The experiments with quantitative and qualitative evaluation demonstrate the effectiveness of the proposed monocular 3D reconstruction system, which can handle the occlusions and collisions between virtual objects and real scenes to achieve realistic AR effects.

Controllable Carbonization of Plastic Waste into Three-Dimensional Porous Carbon Nanosheets by Combined Catalyst for High Performance Capacitor.

Polyethylene terephthalate (PET) plastic has been extensively used in our social life, but its poor biodegradability has led to serious environmental pollution and aroused worldwide concern. Up to now, various strategies have been proposed to address the issue, yet such strategies remain seriously impeded by many obstacles. Herein, waste PET plastic was selectively carbonized into three-dimensional (3D) porous carbon nanosheets (PCS) with high yield of 36.4 wt%, to be further hybridized with MnO2 nanoflakes to form PCS-MnO2 composites. Due to the introduction of an appropriate amount of MnO2 nanoflakes, the resulting PCS-MnO2 composite exhibited a specific capacitance of 210.5 F g-1 as well as a high areal capacitance of 0.33 F m-2. Furthermore, the PCS-MnO2 composite also showed excellent cycle stability (90.1% capacitance retention over 5000 cycles under a current density of 10 A g-1). The present study paved an avenue for the highly efficient recycling of PET waste into high value-added products (PCSs) for electrochemical energy storage.

Conductive and Elastic 3D Helical Fibers for Use in Washable and Wearable Electronics.

Due to the intrinsic properties of fabrics, fabric-based wearable systems have certain advantages over elastomeric material-based stretchable electronics. Here, a method to produce highly stretchable, conductive, washable, and solderable fibers that consist of elastic polyurethane (PU) fibers and conductive Cu fibers, which are used as interconnects for wearable electronics, is reported. The 3D helical shape results from stress relaxation of the prestretched PU fiber and the plasticity of the Cu fiber, which provides a predictable way to manipulate the morphology of the 3D fibers. The present fibers have superior mechanical and electrical properties to many other conductive fibers fabricated through different approaches. The 3D helical fibers can be readily integrated with fabrics and other functional components to build fabric-based wearable systems.

Visualizing Morphogenesis through Instability Formation in 4-D Printing.

Heterogeneous growth in a myriad of biological systems can lead to the formation of distinct morphologies during the maturation processes of different species. We demonstrate that the distinct circumferential buckling observed in pumpkins can be reproduced by a core-shell barrel structure using four-dimensional (4D) printing, taking advantage of digital light processing (DLP)-based three-dimensional (3D) printing and stimulus-responsive hydrogels. The mechanical mismatch between the stiff core and compliant shell results in buckling instability on the surface. The initiation and development of the buckling are governed by the ratio of core/shell radius, the ratio of core/shell swelling ratios, and the mismatch between the core and shell in stiffness. Furthermore, the rigid core not only acts as a source of circumferential confinement but also sets a boundary at the poles of the entire structure. The heterogeneous structures with controllable buckling geometrically and structurally behave much like plants' fruits. This replicates the biological morphologic change and elucidates the general mechanism and dynamics of the complex instability formation of heterogeneous 3D objects.