Elastomeric Origami: Programmable Paper‐Elastomer Composites as Pneumatic Actuators

The development of soft pneumatic actuators based on composites consisting of elastomers with embedded sheet or fiber structures (e.g., paper or fabric) that are flexible but not extensible is described. On pneumatic inflation, these actuators move anisotropically, based on the motions accessible by their composite structures. They are inexpensive, simple to fabricate, light in weight, and easy to actuate. This class of structure is versatile: the same principles of design lead to actuators that respond to pressurization with a wide range of motions (bending, extension, contraction, twisting, and others). Paper, when used to introduce anisotropy into elastomers, can be readily folded into 3D structures following the principles of origami; these folded structures increase the stiffness and anisotropy of the elastomeric actuators, while being light in weight. These soft actuators can manipulate objects with moderate performance; for example, they can lift loads up to 120 times their weight. They can also be combined with other components, for example, electrical components, to increase their functionality.     

Deployable Structures Based on Buckling of Curved Beams Upon a Rotational Input

Inspired by the recent success of buckling-induced reconfigurable structures, a new class of deployable systems that harness buckling of curved beams upon a rotational input is proposed. First, experimental and numerical methods are combined to investigate the influence of the beam's geometric parameters on its non-linear response. Then, it is shown that a wide range of deployable architectures can be realized by combining curved beams. Finally, the proposed principles are used to build deployable furniture such as tables and lamp shades that are flat/compact for transportation and storage, require simple or no assembly, and can be expanded by applying a simple rotational input.     

Active Reconfigurable Tristable Square‐Twist Origami

Origami structures offer valuable applications in many fields, ranging from metamaterials to robotics. The multistable characteristics of origami structures have been pursued for acquiring unique reconfigurable features. For achieving this goal, an unusual polymeric tristable origami structure is demonstrated using a classic square‐twist origami configuration. By manipulating both material properties and geometric parameters of the heteropolymer structures, a design principle for tailoring the multistable configuration in the square‐twist origami is established based on variation of the structural potential energy. Under thermal triggering, the stiffness of the deformable structure is dramatically reduced, which causes an increase in the structural degree of freedom, allowing for self‐deployment via release of the prestored energy in the elastic twisted hinges. Utilizing such unique features and design principles, a prototype of frequency reconfigurable origami antenna of five diverse operating modes and a programmable multiple‐input multiple‐output communication system is subsequently designed and assembled, aiming to substantially promote the channel capacity and communication reliability. The findings and results firmly provide a remarkable design principle and strategy for advancing active origami structures and devices in shape‐morphing systems.     

Elastically and Plastically Foldable Electrothermal Micro‐Origami for Controllable and Rapid Shape Morphing

Integrating origami principles within traditional microfabrication methods can produce shape morphing microscale metamaterials and 3D systems with complex geometries and programmable mechanical properties. However, available micro‐origami systems usually have slow folding speeds, provide few active degrees of freedom, rely on environmental stimuli for actuation, and allow for either elastic or plastic folding but not both. This work introduces an integrated fabrication–design–actuation methodology of an electrothermal micro‐origami system that addresses the above‐mentioned challenges. Controllable and localized Joule heating from electrothermal actuator arrays enables rapid, large‐angle, and reversible elastic folding, while overheating can achieve plastic folding to reprogram the static 3D geometry. Because the proposed micro‐origami do not rely on an environmental stimulus for actuation, they can function in different atmospheric environments and perform controllable multi‐degrees‐of‐freedom shape morphing, allowing them to achieve complex motions and advanced functions. Combining the elastic and plastic folding enables these micro‐origami to first fold plastically into a desired geometry and then fold elastically to perform a function or for enhanced shape morphing. The proposed origami systems are suitable for creating medical devices, metamaterials, and microrobots, where rapid folding and enhanced control are desired.     

Investigation of Magnetotaxis of Reconfigurable Micro‐Origami Swimmers with Competitive and Cooperative Anisotropy

Recent advances in magnetic nanocomposites have enabled untethered micromachines with controllable shape transformations and programmable magnetic anisotropy, paving the way for a variety of biomedical applications using soft microrobots. Magnetic anisotropy is programmed by assembling the embedded magnetic nanoparticles (MNPs) in polymeric materials to overcome the shape anisotropy of a given structure. However, this approach is questionably effective in reconfigurable structures, as shape changes naturally result in rearrangement of the embedded MNPs. A naturally occurring solution to this problem is found in magnetotactic bacteria, which build chains of MNPs in a linear‐chain formation in their cells to create a permanent magnetic dipole moment. This dipole moment enables them to actively sense magnetic fields and coordinate their movement in response, a behavior called magnetotaxis. Inspired by this, self‐folding micro‐origami swimmers comprising magnetic nanocomposite bilayer structures that exhibit controllable shape transformations and programmable, shape‐independent magnetotaxis is fabricated. A study of these structures reveals that their magnetic anisotropy results from competition or cooperation between anisotropy of assembled chains of MNPs and overall shape anisotropy. Moreover, how the magnetotaxis of the reconfigurable micro‐origami swimmers depends only on the embedded permanent dipole moment, independent of the overall magnetic anisotropy, is demonstrated.     

Frequency-, radiation pattern- and polarization-reconfigurableantenna for wireless applications

In this communication, a frequency-, radiation pattern-and polarization-reconfigurable antenna employing liquid metal is presented. Two crossed dipole antennas are surrounded by four independent reflectors and directors to realize multi-beam switching. The length of dipole arms can be adjusted by extracting the liquid metal from the needle tube to achieve frequency reconfiguration. The polarization can be switched by injecting liquid metal into different dipole microfluidic channels. It is simpl...     

Cassegrain Antenna With Hybrid Beam Steering Scheme for Mobile Satellite Communications

A hybrid antenna (HA) with a modified beam steering method is proposed. This antenna has a Cassegrain structure composed of two reflectors and a feeder. The parabolic-shaped main reflector is designed for high gain, while the subreflector is rotational and flat. The feeder is a phased array with arbitrary shaped aperture and 20 element antennas. The HA is capable of two-dimensional beam steering by means of two operations: rotation of the subreflector and phase control of the feed array. The subreflector is small in size and weight, so it can provide rapid beam scanning. Designed to be loaded in vehicles, the HA and can communicate with satellites on the move by tracking the beam control of the feed array. A prototype of the HA is fabricated with aluminum using a machining center operated by computerized numerical control. The prototype is operated at Ka-band for TX and K-band for RX with gains of 47 dBi and 44.4 dBi, respectively, at a steering angle of 0 $^{circ}$. The two-dimensional beam steering within $pm 2^{circ}$ with respect to 45$^{circ}$ elevation is realized by the subreflector and feed array. All radiation patterns in the beam steering zone meet ITU-R s.465-5 regulations.      

一种基于并串结合方式的波控系统设计

针对相控阵雷达波控系统的特点,提出了一种基于并串结合方式的波控系统,实现对相控阵雷达众多T/R组件的波束控制.本文指出了几种常用波控系统设计的优缺点,重点介绍了本波控系统设计的原理、组成和具体实现方法,并介绍了该波控系统设计在各方面带来的改进,包括布相时间短、波束切换快、系统扩展方便,同时能够有效的减少阵面走线、提高波控系统的可靠性和可维修性.     

An electronically switchable leaky wave antenna

We report an electronically switchable dielectric leaky wave antenna. The main beam angle can be electronically steered using p-i-n diodes. The diodes are used as switches to control the radiation from two sets of gratings with different periods, thereby switching the main beam angle. Beam steering is achieved at a single fixed frequency; no frequency sweeping is necessary. A microwave prototype demonstrates a 35° change in beam direction at 3.5 GHz. Measured antenna patterns agree with theoretical predictions. This approach should be scalable to millimeter-wave frequencies using diodes monolithically integrated on a semiconductor waveguide     

Elastomeric Tiles for the Fabrication of Inflatable Structures

This paper describes the fabrication of 3D soft, inflatable structures from thin, 2D tiles fabricated from elastomeric polymers. The tiles are connected using soft joints that increase the surface area available for gluing them together, and mechanically reinforce the structures to withstand the tensile forces associated with pneumatic actuation. The ability of the elastomeric polymer to withstand large deformations without failure makes it possible to explore and implement new joint designs, for example “double‐taper dovetail joints,” that cannot be used with hard materials. This approach simplifies the fabrication of soft structures comprising materials with different physical properties (e.g., stiffness, electrical conductivity, optical transparency), and provides the methods required to “program” the response of these structures to mechanical (e.g., pneumatic pressurization) and other physical (e.g., electrical) stimuli. The flexibility and modularity of this approach is demonstrated in a set of soft structures that expanded or buckled into distinct, predictable shapes when inflated or deflated. These structures combine easily to form extended systems with motions dependent on the configurations of the selected components, and, when fabricated with electrically conductive tiles, electronic circuits with pneumatically active elements. This approach to the fabrication of hollow, 3D structures provides routes to new soft actuators.     

基于查表法的波控系统的设计与实现

波束控制系统是相控阵雷达的重要组成部分。介绍了一种用查表法完成阵面所有单元布相的方法。重点介绍了这种波控系统的原理、组成和具体实现方法。基本思想是先计算得到各移相器的控制码数据,并将控制码编写成查找表格,存储到存储器中。扫描和跟踪时,根据波束指向数据,查得各移相器的控制码,装订到各移相器中。其特点是系统结构简单、集成度高、设备量少、布相时间短。该方法既简单又实用,已用于某大型有限电扫相控阵雷达。     

Fold 2D Woven DNA Origami to Origami+ Structures

DNA origami strategy has greatly promoted the development of DNA nanotechnology as it can construct delicate 2D/3D nanostructures. The current method to prepare DNA origami is through a woven approach to fix a long strand of DNA into certain shapes. This article describes a novel strategy to fold the same 2D DNA sheet into multiple complex structures driven by introducing hydrophobic interaction. The pathway of the folding process can be adjusted by tuning the distribution and chronic order of cholesterol, resulting in different complicated structures. This method is proven efficient for constructing variable nanostructures based on the same DNA origami sheet, and termed as origami⁺. This work represents a new strategy in DNA nanotechnology and will improve the ability to manipulate objects at nanoscale.     

Origami NdFeB Flexible Magnetic Membranes with Enhanced Magnetism and Programmable Sequences of Polarities

Permanent magnets are essential components for many biomedical systems and electromechanical devices, which may be made into flexible formats to achieve wearable monitoring and effective integration with biological tissues. However, the development of high‐performance flexible permanent magnets is challenging due to their ultrathin geometries, which contradict with the thickness‐dependent magnetic properties. In addition, magnetic membranes with controllable sequences of polarities are difficult to achieve. Here, origami techniques to achieve flexible permanent magnetic membranes with enhanced magnetic field strength and programmable sequences of polarities are presented. Linear Halbach arrays, circular Halbach arrays, and concentric magnets with thicknesses ranging from 130 to 500 µm and bending curvatures ranging from 0.039 to 0.0043 µm^?1 are achieved through different folding mechanisms. The origami membranes offer a maximum field intensity of 72 mT and extremely strong magnetic force of 0.21 N cm^?2, allowing various novel applications demonstrated through electronics interfacing, cell manipulations, and soft robotics. The origami techniques offer large magnetism and complex spatial field distribution, and enable practical use of thin flexible magnetic membranes in constructing miniaturized or even flexible electromechanical systems and biomedical instruments for magnetic resonance imaging, targeted drug delivery, health monitoring, and cancer therapy.     

Controllable Stiffness Origami “Skeletons” for Lightweight and Multifunctional Artificial Muscles

Flexible, material‐based, artificial muscles enable compliant and safe technologies for human–machine interaction devices and adaptive soft robots, yet there remain long‐term challenges in the development of artificial muscles capable of mimicking flexible, controllable, and multifunctional human activity. Inspired by human limb's activity strategy, combining muscles' adjustable stiffness and joints' origami folding, controllable stiffness origami “skeletons,” which are created by laminar jamming and origami folding of multiple layers of flexible sandpaper, are embedded into a common monofunctional vacuumed‐powered cube‐shaped (CUBE) artificial muscle, thereby enabling the monofunctional CUBE artificial muscle to achieve lightweight and multifunctionality as well as controllable force/motion output without sacrificing its volume and shape. Successful demonstrations of arms self‐assembly and cooperatively gripping different objects and a “caterpillar” robot climbing different pipes illustrate high operational redundancy and high‐force output through “building blocks” assembly of multifunctional CUBE artificial muscles. Controllable stiffness origami “skeletons” offer a facile and low‐cost strategy to fabricate lightweight and multifunctional artificial muscles for numerous potential applications such as wearable assistant devices, miniature surgical instruments, and soft robots.     

空间衍射望远镜自展开结构设计

为了满足空间探测对衍射望远镜的发展需求,针对某衍射光学系统设计了一种空间可展开衍射望远镜。首先,根据Serrurier桁架原理及优化设计理论确定了文中所用展开结构的形式及几何尺寸,并针对某衍射光学系统设计了一种新型自展开结构;其次,建立了该展开结构的有限元模型并分析了其展开后的特性;最后,搭建了原理样机并对其进行了实验研究。实验结果表明:该展开结构的展开距离为2.9 m,展开后的重复精度误差小于2 mm,偏心小于0.3 mm,倾角小于0.2,且可通过促动器将其展开精度调整至微米级,能够满足空间衍射望远镜自展开机构的结构简单、质量轻、稳定可靠、精度高等要求。     

Highly Stretchable and Strain-Insensitive Liquid Metal based Elastic Kirigami Electrodes (LM-eKE) (Adv. Funct. Mater. 30/2023)

Kirigami, a traditional paper-cutting art, is a promising method for creating mechanically robust circuitry for unconventional devices capable of extreme stretchability through structural deformation. In this study, this design approach is expanded upon by introducing Liquid Metal based Elastic Kirigami Electrodes (LM-eKE) in which kirigami-patterned soft elastomers are coated with eutectic gallium-indium (EGaIn) alloy. Overcoming the mechanical and electrical limitations of previous efforts with paper-like kirigami, the all soft LM-eKE can be stretched to 820% strain while the electrical resistance only increases by 33%. This is enabled by the fluidic properties of the EGaIn coating, which maintains high electrical conductivity even as the elastic substrate undergoes extreme deformation. Applying the LM-eKE to human knee joints and fingers, the resistance change during physical activities is under 1.7%, thereby allowing for stable electrical operation of wearable health monitoring devices for tracking electroencephalogram (EEG) signals and other physiological activity.     

Mechanically Programmable Dip Molding of High Aspect Ratio Soft Actuator Arrays

This work presents multiple methods of creating high aspect ratio fluidic soft actuators that can be formed individually or in large arrays via dip coating. Within this methodology, four strategies are provided to mechanically program the motion of these actuators, including the use of fiber inclusions, gravity, surface tension, and electric fields. The modular nature of this dip coating fabrication technique is inexpensive, easy to modify, and scalable. These techniques are used to demonstrate the fabrication of soft actuators with aspect ratios up to 200:1 and integrated arrays of up to 256 actuators. Furthermore, these methods have the potential to achieve higher aspect ratios and larger array sizes. Operating pressure, curvature, and curling strength tests reveal the design space in which fabrication parameters can be selected to tune the input and output parameters of soft bending actuators. An individual bending actuator made with these methods weighs between 0.15 and 0.5 g, can hold up to 2 N, and can be designed to work in groups to increase curling strength with distributed contact forces. Arrays of these actuators may be useful in atypical grasping and manipulation tasks, fluid manipulation, and locomotion.     

基于DNA折纸术求解图的顶点着色问题的方法

该文基于DNA折纸术,设计了一个通过DNA折纸结构的自组装求解图的顶点着色问题的方法。利用DNA折纸术可以构建出具有特定形状的DNA折纸结构。这些结构可以用来编码图的顶点和边,由于这些结构具有粘性末端,因此可以通过特异的分子杂交组装成为代表了不同的图的顶点着色方案的高级结构。利用DNA-纳米颗粒共聚体的属性和电泳等实验方法,可以筛选出正确的符合条件的图的顶点着色方案。该方法是一种高度并行的方法,可以极大地降低求解图的顶点着色问题的复杂度。     

Null steering in phased arrays by controlling the element positions

Null steering methods usually involve costly and complicated amplitude and/or phase control systems. A technique is presented for null steering based on the element position perturbations. The technique frees the phase shifters to be used solely for steering the main beam toward the direction of the desired signal. It also removes the limitations of the other techniques by independently steering the main beam and the nulls to arbitrary independent directions. This technique is also capable of obtaining sidelobe cancellation and wideband signal rejection     

相控阵雷达波控系统的设计

讨论了相控阵雷达波控系统的设计。应用查表法完成波束控制.通过模块化设计组合使系统简洁实用,而远程调试监控系统具有良好的通用性。