1,720,997 research outputs found
Low-voltage dielectric elastomer actuators with stretchable electrodes fabricated by supersonic cluster beam implantation
No full textSupersonic cluster beam implantation of Ag nanoparticles is proposed for the fabrication of stretchable and compliant electrodes for dielectric elastomer actuators (DEAs) with reduced thickness. Thanks to the low-energy and finely tunable implantation process, a nanocomposite Ag/polydimethylsiloxane electrode layer is produced with a moderate stiffening effect for the DEA in contrast with a common deposition strategy for electrodes. Thin DEAs with an overall thickness of 17 μm were fabricated and tested under different preloading conditions, demonstrating a max uniaxial actuation strain of 2.5% at an actuation voltage of 765 V, lower than the typical voltage values of DEAs. The electrodes remained conductive up to 40% strain, and they fully recovered the original resistance after 70% stretching. Our results represent a significant step towards the development of DEAs operating at reduced actuation voltages, by stacking of micrometer-thick elastomer films, paving the way to novel applications in soft robotics
How does buoyancy of hydrogel microrobots affect their magnetic propulsion in liquids?
No full textGravity compensation is a key requirement for achieving three-dimensional navigation of magnetic microrobots in fluids. Here we present a brief theoretical introduction to the issue of gravity compensation in the case of magnetic pulling propulsion, explicitly highlighting the constraints it introduces. Therefore, we evaluate the advantages that quasi-neutral buoyancy gives to hydrogel microrobots, demonstrating that despite their relatively weak magnetic properties, for certain size/velocity ranges they could be more easily and efficiently propelled than state-of-the-art metal microrobots. Hence, our analysis endorses the adoption of smart polymers, such as stimuli-responsive hydrogels, for developing truly multifunctional magnetic microrobots. © 2013 American Institute of Physics
Modeling of a propulsion mechanism for swimming microrobots inspired by ciliate metachronal waves
No full textThe envisioned applications of microrobots in bodily fluids have raised the demand for effectively swimming microdevices. Microorganisms have become a source of inspiration because their mechanisms of propulsion are effective at low-Re. We investigated the theoretical performance of swimming microrobots implementing propulsion inspired by metachronal waves. These come from the spontaneous coordination of cilia and are responsible for the high swimming speeds of ciliates. We found that microrobots of typical length below the millimeter could self-propel at speeds of several bodylengths per second. The microrobots were assumed to have a continuous active surface exhibiting traveling-wave deformations that mimic metachronal waves. We developed an FE model for analyzing the performance of propulsion of such bio-inspired microrobots in water. In particular we evaluated how velocity is affected by various parameters, such as the shape and size of the microrobot, and the frequency, wavelength and amplitude of the surface deformations. We believe that the proposed mechanism is advantageous over other methods of propulsion because it does not need external thin and fragile appendages. The results of this analysis could thus guide us towards the design of effective self-propelling microrobots. © 2012 IEEE
Novel Smart Concepts for Designing Swimming Soft Microrobots
No full textAbstractThe development of mobile un-tethered microscale robots could revolutionize the future of medicine, since they can be conceived to move in micro-structured liquid environments, such as in inaccessible districts of the human body for performing in vivo diagnosis and therapy. However, power supply and actuation are still open issues in microrobotics, because of the lack of power sources and actuators at these scales. Considering the amazing levels of functionality exhibited by microorganisms, bioinspiration is an attractive approach to address the development of innovative solutions. The demonstration of efficient methods for building, powering and steering microscale robots are thus the first crucial steps towards such advanced systems
Bioinspired Design and Energetic Feasibility of an Autonomous Swimming Microrobot
No full textA mobile microrobot is an untethered robotic device with typical size ranging from few micrometres to few millimetres. Endowing such a microrobot with autonomy-oriented capabilities, e.g. self-propulsion and self-powering, represents a scientific and technological challenge that requires innovative approaches. Bioinspiration provides fundamental cues for designing microrobots, enabling the development of working devices. Here we present the conceptual design of an autonomous swimming microrobot relying on biomimetic glucose-based powering, reporting a preliminary analysis on its energetic feasibility. © 2013 Springer-Verlag Berlin Heidelberg
DLP-Printable Porous Cryogels for 3D Soft Tactile Sensing
Full text linkThree-Dimensional (3D) printed porous materials hold the potential for various soft sensing applications due to their remarkable flexibility, low density, and customizable geometries. However, developing versatile and efficient fabrication methods is crucial to unlock their full potential. A novel approach is introduced by combining Digital Light Processing (DLP) 3D printing and freeze-drying to manufacture deformable cryogels featuring intricate morphologies. Photocurable hydrogels based on Poly(3,4-ethylenedioxythiophene)Polystyrene sulfonate (PEDOT:PSS), Polyethylene glycol Diacrylate (PEGDA) and Ethylene Glycol (EG) are successfully printed and lyophilized. In this way, porous cryogels with tailorable properties are achieved. Microporosity varies from 68% to 96%, according to the chemical composition. Ultra-soft cryogels with a compressive modulus of 0.13MPa are fabricated by adding a reactive diluent. As a result of the cryogelation process, which effectively removes water from the hydrogels, microporous structures with details as fine as 100 mu m are obtained. The achieved freedom of design is exploited to fabricate resistive force sensors with a honeycomb lattice morphology. The sensitivity and the working range of the sensors can be tailored by tuning the size of the cells, paving the way for sensors with programmable architectures that can meet diverse requirements.A dual-step approach combining Digital Light Processing (DLP) 3D printing and lyophilization transforms printed hydrogels into porous cryogels with complex shapes. Porosity and mechanical properties are finely controlled based on the chemical composition of starting formulations. Microporous cryogels with details down to 100 mu m are printed. Proof-of-concept scalable soft force sensors show a tuneable response based on the geometry of the core 3D honeycomb architecture. imag
A soft, stretchable and conductive biointerface for cell mechanobiology
No full textIn mechanobiology the study of cell response to mechanical stimuli is fundamental, and the involved processes (i.e., mechanotransduction) need to be investigated by interfacing (mechanically and electrically) with the cells in dynamic and non-invasive natural-like conditions. In this work, we present a novel soft, stretchable and conductive biointerface that allows both cell mechanical stimulation and dynamic impedance recording. The biointerface stretchability and conductivity, jointly to the biocompatibility and transparency needed to perform cell culture studies, were obtained by exploiting the formation of wrinkles on the surface of a 90 nm thick conductive layer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on a pre-stretched 130 μm thick poly(dimethylsiloxane) (PDMS) substrate. Cell adhesion and proliferation of SH-SY5Y human neuroblastoma cells were evaluated, and cell differentiation on the corrugated surface was assessed. We demonstrate how the biointerface remains conductive when applying uniaxial strain up to 10 %, and when cell culturing is performed. Finally, a reduction of about 30 % of the relative impedance variation signal was measured, with respect to the control, as a result of the mechanical stimulation of cells
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
