超磁致伸缩材料在骨传导听觉装置上的应用

超磁致伸缩材料(简称GMM)是制作低频换能器的理想功能材料。介绍了GMM的磁致伸缩机理及其本身特性;与传统磁致伸缩材料以及当前广泛应用在骨传导听觉装置上的电磁和压电材料进行了分析比较;综述了GMM在骨传导听觉装置上的应用现状;重点介绍了骨传导发音振子的设计构想,并且对超磁致伸缩式骨传导听觉装置在军事通信上的应用进行了展望。     

Researches on the computer digital control system of giant magnetostrictive actuator

In this paper, a computer digital control system of giant magnetostrictive actuator (GMA) was designed. In GMA system, driving magnetic field was provided by variable magnetic field generated by exciting coil current and offset magnetic field generated by permanent magnet. And Terfernol-D was used as the giant magnetostrictive materials (GMM). GMA’s control model was analysed and the whole control system was established. In the computer digital control system, the control core were single-chip microcomputer and PC with modularization thinking. And the control algorithm was PID. Design for system’s hardware and software was completed and software package was developed. Experiment shows that the GMA system is controlled automatically and monitored real-time. It lays a foundation of further improving control precision of GMA, improving the entire system’s dynamic characteristics and realizing automatic control.     

超磁致伸缩换能器的磁场和温度场分析及其结构设计

本文针对超磁致伸缩换能器磁路设计进行分析,包括驱动器磁路设计、磁路分析与设计、偏置磁场设计、激励线圈设置、超磁致伸缩棒的处理等,结合超磁致伸缩换能器发热分析,通过研究换能器磁场有限元、伸缩棒磁场有限元、伸缩换能器温度场有限元、样机与测试、测试结果分析等内容,目的在于提高超磁致伸缩换能器运行的稳定性,提升系统运行的可靠性。     

MEMS 静电执行光开关的设计与实验

介绍了一种基于静电执行的自对准型垂直镜面微机械光开关，该光开关由垂直反射镜面、悬臂梁、光纤定位槽等组成。微反射镜和V型光纤定位槽的自对准由同一块掩膜板实现。微反射镜和V字型光纤槽通过对(100)单晶硅的各向异性腐蚀实现。论文给出光开关的结构设计，并实验验证了上述自对准光开关的加工工艺。     

磁致伸缩换能器热声制冷机结构设计与验证

在分析热声制冷装置热声转换原理的基础上,对微型热声制冷机主要零部件的结构参数进行设计和计算,确定了一种以磁致伸缩换能器驱动的热声制冷机系统结构。用ANSYS软件对所述系统进行流体动力学分析。实验结果表明,该系统在给定的边界条件下,板叠内部产生热声效应,从热端到冷端有明显的温降。通过实验验证了所得制冷机结构的可行性,为微型磁致伸缩换能器热声制冷机进一步优化设计提供了基础。     

形状记忆合金薄膜驱动微泵的动态特性

一种用形状记忆合金薄膜驱动的新型微泵已经研制成功。为了进一步提高微泵性能，研究了微泵在不同驱动条件下的动态特性。结果表明，随着驱动电流和频率的增加，驱动膜有一个最大的位移植。占空比对最大位移的影响在有无流体情况下是不同的。微泵的流量不仅仅由驱动膜的位移决定，它还与驱动频率有关。在给定的频率下，位移越大，输出流量也越大。动态驱动过程中NiTi电阻的变化表明，形状记忆合金薄膜的马氏体←→奥氏体相转变是不完全的。     

巨磁致伸缩快速转向反射镜及其谐振频率

快速转向反射镜(FSM)广泛应用于激光束稳定系统、空间光通信系统等领域。采用巨磁致伸缩驱动器(GMA)作为FSM的驱动元件,并对其预压和传动机构进行了一体化优化,设计了一种新型的膜片式柔性上端盖作为预压力施加装置,使其结构更加紧凑的同时增强了位移径向约束;FSM采用四驱动器双驱动轴结构,应用柔性轴方案,对其整体结构进行了优化设计以提高系统谐振频率。建立了FSM有限元模型,对其进行模态分析得到了系统一阶谐振频率及模态振型。对所研制的FSM进行了性能测试,结果表明:系统镜面转角达到±3′,一阶机械谐振频率达到450 Hz,模态分析数值与实验值的误差小于10%。     

柔性仿生磁性微结构的制备与驱动

根据自然界中一些在黏性介质中游动的生物的运动原理,制备了一种由磁性头部和无磁性尾部构成的柔性仿生微结构,可通过均匀振荡磁场驱动。结合振荡磁场的产生原理建立运动学模型,以分析磁性微结构在振荡磁场驱动下的振荡特性。在驱动过程中分别设置磁场的振荡角为60°、90°和120°,微结构的游动速度随着磁场振荡角的增大而增加。通过研究微结构在驱动过程中的频率响应,确定了微结构在振荡角为60°、失步频率为15 Hz时,获得的最大游动速度为105μm/s,而当振荡角为90°和120°、失步频率为25 Hz时,获得的最大游动速度分别为117和179μm/s。低于失步频率时,游动速度随着频率的增加而增大,但是高于失步频率后,游动速度随之降低。结合微结构的振荡模型,分析了失步的原因,并论证了微结构的振荡角和振荡频率在频率响应中的作用机制。     

Wedge-wave transduction by means of interdigital electrodes

Experimental results on wedge-wave transduction by means of interdigital electrodes are presented. It is shown that tightly confined low-velocity wedge waves can be launched with high efficiency. Experiments on both PZT and LiNbO3 wedges are reported.     

Polyampholyte Hydrogels with pH Modulated Shape Memory and Spontaneous Actuation

Polyampholyte hydrogels are synthesized by one‐step copolymerization of cationic monomer 3‐(methacryloylamino)propyltrimethylammonium chloride, anionic monomers sodium p‐styrenesulfonate (NaSS), and methacrylic acid (MAA) without chemical crosslinker and adding salts. The hydrogels exhibit pH responsive shape memory behavior; the temporary shape of the hydrogel is formed manually after immersing in NaOH solution and fixed in HCl solution, while the shape recovery occurs by immersing in NaOH again. Most interestingly, the hydrogel shows a spontaneous shape change after the first shape memory cycle. When the recovered hydrogel with a little residual deformation is immersed in HCl again, it twists spontaneously and rapidly to the previous temporary shape. The spontaneous twisting and recovering can be repeated for ten times. Furthermore, the hydrogel swells quickly and is strengthened in HCl, while shrinks and weakens in NaOH during the shape change procedure. This unique synergistic effect of fast swelling, residual helical deformation, and increased strength plays a significant role in the spontaneous shape alternation. This new finding will initiate a new prosperous design for new soft actuators requiring successive actions.     

关于压电致动器的动力学和致动作用力

从压电本构方程出发，将外加电信号处理为外界激励作用。在理论上给出了应用最广泛的矩形薄板压电致动器在激励作用下的动力学效应，同时给出了其致动作用力表达式，为以前的有关报道结果提供了严格的理论依据。根据结果不难具体分析这种压电致动器的动力学响应。     

Comparison of MRI-Compatible Mechatronic Systems With Hydrodynamic and Pneumatic Actuation

The strong magnetic fields and limited space make it challenging to design the actuation for mechatronic systems intended to work in MRI environments. Hydraulic and pneumatic actuators can be made MRI-compatible and are promising solutions to drive robotic devices inside MRI environments. In this paper, two comparable haptic interface devices, one with hydrodynamic and another with pneumatic actuation, were developed to control one-degree-of-freedom translational movements of a user performing functional MRI (fMRI) tasks. The cylinders were made of MRI-compatible materials. Pressure sensors and control valves were placed far away from the end-effector in the scanner, connected via long transmission lines. It has been demonstrated that both manipulandum systems were MRI-compatible and yielded no artifacts to fMRI images in a 3-T scanner. Position and impedance controllers achieved passive as well as active subject movements. With the hydrodynamic system we have achieved smoother movements, higher position control accuracy, and improved robustness against force disturbances than with the pneumatic system. In contrast, the pneumatic system was back-drivable, showed faster dynamics with relatively low pressure, and allowed force control. Furthermore, it is easier to maintain and does not cause hygienic problems after leakages. In general, pneumatic actuation is more favorable for fast or force-controlled MRI-compatible applications, whereas hydrodynamic actuation is recommended for applications that require higher position accuracy, or slow and smooth movements.     

Soft Optomechanical Systems for Sensing,Modulation, and Actuation

Soft optomechanical systems have the ability to reversibly respond to optical and mechanical external stimuli by changing their own properties (e.g., shape, size, viscosity, stiffness, color or transmittance). These systems typically combine the optical properties of plasmonic, dielectric or carbon-based nanomaterials with the high elasticity and deformability of soft polymers, thus opening the path for the development of new mechanically tunable optical systems, sensors, and actuators for a wide range of applications. This review focuses on the recent progresses in soft optomechanical systems, which are here classified according to their applications and mechanisms of optomechanical response. The first part summarizes the soft optomechanical systems for mechanical sensing and optical modulation based on the variation of their optical response under external mechanical stimuli, thereby inducing mechanochromic or intensity modulation effects. The second part describes the soft optomechanical systems for the development of light induced mechanical actuators based on different actuation mechanisms, such as photothermal effects and phase transitions, among others. The final section provides a critical analysis of the main limitations of current soft optomechanical systems and the progress that is required for future devices.     

Fast and Ample Light Controlled Actuation of Monodisperse All-DNA Microgels

The assembly of adaptive hierarchical soft materials that resemble living tissues requires responsive building blocks of controlled dimensions. While DNA self-assembly provides an exceptional tool for nanoscale architectural control, responsive DNA microstructures remain scarce. Here, two challenges controlling the size of DNA microstructures and embedding them with fast and ample structural response are addressed. For size-control, arrested phase separation and microfluidic confinement are combined to produce monodisperse all-DNA particles. For responsiveness, a light controlled coil-globule transition of the microgel DNA network powered by an azobenzene cationic surfactant is implemented. The photoinduced trans-cis isomerization of the azobenzene moiety reduces its affinity for DNA which results in fast, large amplitudes microgel swelling. Finally, the assembly of light responsive microgel superstructures is demonstrated as proof-of-concept hierarchical all-DNA materials.     

Mixing and detection of RF signals in fibre-optic magnetostrictive sensor

The author report the first demonstration of the detection of magnetic fields at frequencies above 50 kHz in a fibre-optic magnetometer using a technique which employs mixing of the signal with the field from a local oscillator. A flat response from 0.1 Hz to near 1.0 MHz is shown.<>     

High-sensitivity low-frequency magnetometer using magnetostrictive primary sensing and piezoelectric signal recovery

A simple and inexpensive magnetometer is presented which uses a piezomagnetic primary sensor together with a piezoelectric transducer to convert a magnetic field into an electrical signal. A linear operating range is achieved by employing a negative feedback configuration. The detection sensitivity is 1.5 x 10-4 A/m per Hz1/2at low frequencies.     

Elastic Energy Storage Enables Rapid and Programmable Actuation in Soft Machines

Storage of elastic energy is key to increasing the efficiency, speed, and power output of many biological systems. This paper describes a simple design strategy for the rapid fabrication of prestressed soft actuators (PSAs), exploiting elastic energy storage to enhance the capabilities of soft robots. The elastic energy that PSAs store in their prestressed elastomeric layer enables the fabrication of grippers capable of zero‐power holding up to 100 times their weight and perching upside down from angles of up to 116°. The direction and magnitude of the force used to prestress the elastomeric layer can be controlled not only to define the final shape of the PSA but also to program its actuation sequence. Additionally, the release of the elastic energy stored by PSAs causes their high‐speed recovery (≈50 ms), which significantly improves the actuation rates of soft pneumatic actuators, especially after motions requiring large deformations. Moreover, judicious prestressing of PSAs can also create bistable soft robotic systems, which use their stored elastic energy as a source of power amplification for rapid movements. These strategies serve as a basis for a new class of entirely soft robots capable of recreating bioinspired high‐powered and high‐speed motions using stored elastic energy.     

金属-压电复合管驱动器静态驱动性能分析

提出了一种新型金属-压电复合管驱动器,以满足微振动主动控制及隔振系统对压电驱动器在位移量、驱动力等性能方面的需求。将管状压电驱动元件粘贴在金属管上,当压电管受外加激励电压作用时,便会在轴向产生伸缩应变,从而使金属管在轴向产生一定的位移量和驱动力。首先对该压电驱动器的静态驱动性能进行理论分析,结果表明,该新型压电驱动器具有中等位移量和驱动力;同时用有限元法对其进行了验证,对于某金属-压电复合管驱动器,通过理论计算和有限元法得到的应变量分别为0.912×10-5、0.925×10-5,从而证明了该理论分析的有效性和正确性;最后设计并制作了一款铜-压电复合管驱动器。     

Hydrogen-Bonded Liquid Crystal Elastomers Combining Shape Memory Programming and Reversible Actuation

Materials that undergo shape morphing in response to external stimuli have numerous applications, e.g., in soft robotics and biomedical devices. Shape memory polymers utilize kinetically trapped states to, typically irreversibly, transfer between a programmed morphed shape and an equilibrium shape. Liquid crystal elastomers (LCEs), in turn, can undergo reversible actuation in response to several stimuli. This study combines the irreversible and reversible shape morphing processes to obtain LCEs that undergo shape-programming via the shape memory effect and subsequent reversible actuation of the programmed shape. This is enabled by an LCE crosslinked via dynamic hydrogen bonds that break at high temperatures and reform upon cooling, endowing the shape memory effect, while mild thermal or photothermal stimulation yields the reversible actuation. Through this combination, proof-of-concept robotic application scenarios such as grippers that can adjust their shape for grabbing different-sized objects and crawling robots that can morph their shape to adapt to constrained spaces, are demonstrated. It is anticipated that this work adds new diversity to shape-programmable soft microrobotics.