73 research outputs found
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
Propulsion of swimming microrobots inspired by metachronal waves in ciliates: from biology to material specifications
No full textThe quest for swimming microrobots originates from possible applications in medicine, especially involving navigation in bodily fluids. Swimming microorganisms have become a source of inspiration because their propulsion mechanisms are effective in the low-Reynolds number regime. In this study, we address a propulsion mechanism inspired by metachronal waves, i.e. the spontaneous coordination of cilia leading to the fast swimming of ciliates. We analyse the biological mechanism (referring to its particular embodiment in Paramecium caudatum), and we investigate the contribution of its main features to the swimming performance, through a three-dimensional finite-elements model, in order to develop a simplified, yet effective artificial design. We propose a bioinspired propulsion mechanism for a swimming microrobot based on a continuous cylindrical electroactive surface exhibiting perpendicular wave deformations travelling longitudinally along its main axis. The simplified propulsion mechanism is conceived specifically for microrobots that embed a micro-actuation system capable of executing the bioinspired propulsion (self-propelled microrobots). Among the available electroactive polymers, we select polypyrrole as the possible actuation material and we assess it for this particular embodiment. The results are used to appoint target performance specifications for the development of improved or new electroactive materials to attain metachronal-waves-like propulsion
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
Integrated Simultaneous Detection of Tactile and Bending Cues for Soft Robotics
No full textSoft robots should move in an unstructured environment and explore it and, to do so, they should be able to measure and distinguish proprioceptive and exteroceptive stimuli. This can be done by embedding mechanosensing systems in the body of the robot. Here, we present a polydimethylsiloxane block sensorized with an electro-optical system and a resistive strain gauge made with the supersonic cluster beam implantation (SCBI) technique. We show how to integrate these sensing elements during the whole fabrication process of the soft body and we demonstrate that their presence does not change the mechanical properties of the bulk material. Exploiting the position of both sensing systems and a proper combination of the output signals, we present a strategy to measure simultaneously external pressure and positive/negative bending of the body. In particular, the optical system can reveal any mechanical stimulation (external from the soft block or due to its own deformation), while the resistive strain gauge is insensitive to the external pressure, but sensitive to the bending of the body. This solution, here applied to a simple block of soft material, could be extended to the whole body of a soft robot. This approach provides detection and discrimination of the two stimuli (pressure and bending), with low computational effort and without significant mechanical constraint
Development and experimental analysis of a soft compliant tactile microsensor for anthropomorphic artificial hand
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