Liquid marbles,formation and locomotion using external fields and forces

Liquid marbles may be traditionally formed by rolling a droplet on a bed of non-wetting particles resulting in encapsulation and stabilisation. Particles used in this process may range from nanometre to millimetre if handled with sufficient care. This method, however, runs the risk of droplet coalescence and is limited to non-wetting particles. Currently there exist some alternative methods of formulation including using electrostatics to either deliver a particle bed to the droplet or pull the droplet to the particles. The former has shown some promise in potential batch processes but is hindered by interparticle forces. Additional production methods include a form of blender, but this has shown to be unable to produce marbles of a narrow size distribution. Once formed, liquid marbles have demonstrated value as potential blood typing devices, as micro-reaction vessels due to the inherent barrier between the internal phase and the substrate whilst maintaining gas permeability, and as contaminant sensors. Liquid marbles also demonstrate a remarkable level of elasticity under compressive force and reduced evaporation rates when compared to bare water droplets, a function of the size and composition of the stabilising particles. In addition to this, liquid marbles have been proposed as actuators. Locomotion may easily be induced in these structures, using electrostatics, sound, magnetism or light depending on the particle/liquid combinations used in formation, and the environment of deployment. This review seeks to present and summarise recent advances in the field of liquid marble manufacture and methods for actuation. We also aim to highlight potential future avenues of further study within this arena.     

航空航天作动系统和元件先进技术国际交流会2016（R3ASC16）介绍

航空航天作动系统和元件先进技术国际交流会,为世界各国作动系统和元件研究团体的设计研发人员提供了交流平台,该会议探讨了当前航空航天作动器技术发展现状和发展趋势,促进先进作动技术的快速发展。本文主要从作动器建模仿真技术、驱动控制技术、健康管理技术、元件设计技术以及标准化进展等方面来提升航空航天作动器的轻量化、高效能、高可靠性、高安全性,同时提升易维护性,降低全生命周期成本。我国在航空航天作动器相关技术方面相对国外存在较大的追赶空间,这次会议展示了世界范围内航空航天作动器的最新技术和产品成果,希望能为国内从事相关工作的研究者提供一定的启发。     

A Novel Micro Ring Structured PPy/pTS Free Standing Film With Improved Actuation Stability

A free-standing PPy/pTS film with a novel micro ring structured surface morphology have been electropolymerized by using CTAB/SDBS catanionic vesicles as templates. Characterizations showed that the micro ring structured PPy/pTS film was chemically similar to typical PPy/pTS films, while some DBS anions were also incorporated into the film from the mixed surfactants solutions. The micro ring structured PPy/pTS showed a slightly lower conductivity than conventional PPy/pTS films, due to the incorporation of DBS anions. The micro ring structured PPy/pTS films showed improved actuation stability compared to the conventional PPy/pTS films.     

The iterative development of a tangible pin-board to symmetrically link physical and digital documents

There is an asymmetry in many tangible interfaces: while physical objects can be used to manipulate digital information, the reverse is often not possible—the digital world cannot push back. We introduce a new push-back tangible technology, a pin-board that physically ejects paper documents. This is realized by extending the Pin&Play technology to support ‘pouts’, addressable pin-like devices that can remove themselves from a board using muscle wire actuators. We describe how this technology has been developed through two iterations of prototyping, application and formative study. An initial study revealed how potential mismatches between the physical and digital characteristics of pouts caused difficulties with users predicting pop-out events and reasoning about the state of pouts. This led us to extend pouts to reveal more of their internal state, an approach verified through a second study. It also raises more general issues for the design of pushback tangible technologies and ubiquitous interfaces.     

Actuation Spaces Synthesis of Lower-Mobility Parallel Mechanisms Based on Screw Theory

The lower-mobility parallel mechanism has been widely used in the engineering field due to its numerous excellent characteristics.However,little work has been devoted to the actuator selection and placement that best satisfy the system's functional requirements during concept design.In this study,a unified approach for synthesizing the actua-tion spaces of both rigid and flexure parallel mechanisms has been presented,and all possible combinations of inputs could be obtained,laying a theoretical foundation for the subsequent optimization of inputs.According to the linear independence of actuation space and constraint space of the lower-mobility parallel mechanism,a general expres-sion of actuation spaces in the format of screw systems is deduced,a unified synthesis process for the lower-mobility parallel mechanism is derived,and the efficiency of the method is validated with two selective examples based on screw theory.This study presents a theoretical framework for the input selection problems of parallel mechanisms,aiming to help designers select and place actuators in a correct and even optimal way after the configuration design.     

A magneto-active scaffold for stimulation of bone growth

Abstract

Creating ‘smart’ biomedical devices with the potential for controlled actuation in vivo has been a long-standing scientific pursuit in therapeutic medicine. The present work focuses on a bone regeneration scaffold based on ferromagnetic fibres designed to induce in vivo modelling of in-growing periprosthetic bone by the application of an external magnetic field of clinical magnitude. We present the conceptual basis of such a ‘magneto-active scaffold’, the properties of prime interest and how these properties can be controlled.     

Optimal design of a redundantly actuated 4-legged six degree of freedom parallel manipulator using composite design index

This work attempts to develop a procedure for the optimal design of a redundantly actuated six degree of freedom parallel manipulator. A concept of composite design index is developed to deal with multi-criteria based design in a systematic manner, and this index is employed to obtain a set of optimal dimensions for this manipulator. Two different designs are investigated, and they are compared in terms of their local characteristics. Finally, the fault-tolerant capability afforded by redundant actuation is evaluated in terms of partial actuator failures.     

Fabrication and electrostatic actuation of thin diaphragms

In this paper, two kinds ofp ⁺ diaphragms are fabricated. One is flat, and the other is corrugated to release the residual stress resulted from the diffusion process. The two diaphragms are electrostatically actuated, and the center deflections of the diaphragms are measured for various frequencies. The static deflections of the flat diaphragm and the corrugated one estimated from the test results are compared with the calculated static deflections under residual tensile stress. The experimental result and the calculated result agree in the case of the flat diaphragm with a reasonable residual stress, but it is not true for the corrugated diaphragm. In the calculation, it is estimated that the corrugated diaphragm deflects more than the flat one. In the experiment, however, the corrugated diaphragm deflects less than the flat one.     

采用传统闭环方法控制电磁气门驱动的可行性分析

以研究电磁气门驱动（EVA）气门落座软着陆控制为目的,依据EVA装置,建立EVA的数学模型并将其线性化,在此基础上对采用传统闭环控制方法的可行性进行了分析,得出结论：用于仿真的模型与实际情况有差别,难以用于评估控制策略;在小气隙下EVA系统可控性较差,且非常不稳定,采用传统的闭环方法控制电磁气门驱动不具有可行性。