118 research outputs found
Bioinspired reorientation strategies for application in micro/nanorobotic control
Engineers have recently been inspired by swimming methodologies of microorganisms in creating micro-/nanorobots for biomedical applications. Future medicine may be revolutionized by the application of these small machines in diagnosing, monitoring, and treating diseases. Studies over the past decade have often concentrated on propulsion generation. However, there are many other challenges to address before the practical use of robots at the micro-/nanoscale. The control and reorientation ability of such robots remain as some of these challenges. This paper reviews the strategies of swimming microorganisms for reorientation, including tumbling, reverse and flick, direction control of helical-path swimmers, by speed modulation, using complex flagella, and the help ofmastigonemes. Then, inspired by direction change in microorganisms,methods for orientation control for microrobots and possible directions for future studies are discussed. Further, the effects of solid boundaries on the swimming trajectories of microorganisms and microrobots are examined. In addition to propulsion systems for artificial microswimmers, swimming microorganisms are promising sources of control methodologies at the micro-/nanoscale
A Novel Propeller Design for Micro-Swimming robot
The applications of a micro-swimming robot such as minimally invasive surgery, liquid pipeline robot etc. are widespread in recent years. The potential application fields are so inspiring, and it is becoming more and more achievable with the development of microbiology and Micro-Electro-Mechanical Systems (MEMS). The aim of this study is to improve the performance of micro-swimming robot through redesign the structure.
To achieve the aim, this study reviewed all of the modelling methods of low Reynolds number flow including Resistive-force Theory (RFT), Slender Body Theory (SBT), and Immersed Boundary Method (IBM) etc. The swimming model with these methods has been analysed. Various aspects e.g. hydrodynamic interaction, design, development, optimisation and numerical methods from the previous researches have been studied.
Based on the previous design of helix propeller for micro-swimmer, this study has proposed a novel propeller design for a micro-swimming robot which can improve the velocity with simplified propulsion structure. This design has adapted the coaxial symmetric double helix to improve the performance of propulsion and to increase stability. The central lines of two helical tails overlap completely to form a double helix structure, and its tail radial force is balanced with the same direction and can produce a stable axial motion.
The verification of this design is conducted using two case studies. The first one is a pipe inspection robot which is in mm scale and swims in high viscosity flow that satisfies the low Reynolds number flow condition. Both simulation and experiment analysis are conducted for this case study. A cross-development method is adopted for the simulation analysis and prototype development. The experiment conditions are set up based on the simulation conditions. The conclusion from the analysis of simulation results gives suggestions to improve design and fabrication for the prototype. Some five revisions of simulation and four revisions of the prototype have been completed. The second case study is the human blood vessel robot. For the limitations of fabrication technology, only simulation is conducted, and the result is compared with previous researches. The results show that the proposed propeller design can improve velocity performance significantly.
The main outcomes of this study are the design of a micro-swimming robot with higher velocity performance and the validation from both simulation and experiment
Bio-Hybrid Micro/Nanodevices Powered by Flagellar Motor: Challenges and Strategies
Molecular motors, which are precision-engineered by nature, offer exciting possibilities for bio-hybrid engineered systems. They could enable real applications ranging from micro/nano fluidics, to biosensing, to medical diagnoses. This review describes the fundamental biological insights and fascinating potentials of these remarkable sensing and actuation machines, in particular bacterial flagellar motors, as well as their engineering perspectives with regard to applications in bio-engineered hybrid systems and nanobiotechnology
Flagellate Underwater Robotics at Macroscale: Design, Modeling, and Characterization
Prokaryotic flagellum is considered as the only known example of a biological “wheel,” a system capable of converting the action of rotatory actuator into a continuous propulsive force. For this reason, flagella are an interesting case study in soft robotics and they represent an appealing source of inspiration for the design of underwater robots. A great number of flagellum-inspired devices exists, but these are all characterized by a size ranging in the micrometer scale and mostly realized with rigid materials. Here, we present the design and development of a novel generation of macroscale underwater propellers that draw their inspiration from flagellated organisms. Through a simple rotatory actuation and exploiting the capability of the soft material to store energy when interacting with the surrounding fluid, the propellers attain different helical shapes that generate a propulsive thrust. A theoretical model is presented, accurately describing and predicting the kinematic and the propulsive capabilities of the proposed solution. Different experimental trials are presented to validate the accuracy of the model and to investigate the performance of the proposed design. Finally, an underwater robot prototype propelled by four flagellar modules is presented
Predicting and Optimizing Microswimmer Performance from the Hydrodynamics of Its Components: The Relevance of Interactions
Interest in the design of bioinspired robotic microswimmers is growing rapidly, motivated by the spectacular capabilities of their unicellular biological templates. Predicting the swimming speed and efficiency of such devices in a reliable way is essential for their rational design, and to optimize their performance. The hydrodynamic simulations needed for this purpose are demanding and simplified models that neglect nonlocal hydrodynamic interactions (e.g., resistive force theory for slender, filament-like objects that are the typical propulsive apparatus for unicellular swimmers) are commonly used. We show through a detailed case study of a model robotic system consisting of a spherical head powered by a rotating helical flagellum that (a) the errors one makes in the prediction of swimming speed and efficiency by neglecting hydrodynamic interactions are never quite acceptable and (b) there are simple ways to correct the predictions of the simplified theories to make them more accurate. We also formulate optimal design problems for the length of the helical flagellum giving maximal energetic efficiency, maximal distance traveled per motor turn, or maximal distance traveled per unit of work expended, and exhibit optimal solutions
Bacteria-inspired Robotic Propulsion from Bundling of Soft Helical Filaments at Low Reynolds Number
The bundling of flagella is known to create a "run" phase, where the bacteria
moves in a nearly straight line rather than making changes in direction.
Historically, mechanical explanations for the bundling phenomenon intrigued
many researchers, and significant advances were made in physical models and
experimental methods. Contributing to the field of research, we present a
bacteria-inspired centimeter-scale soft robotic hardware platform and a
computational framework for a physically plausible simulation model of the
multi-flagellated robot under low Reynolds number (~0.1). The fluid-structure
interaction simulation couples the Discrete Elastic Rods algorithm with the
method of Regularized Stokeslet Segments. Contact between two flagella is
handled by a penalty-based method. We present a comparison between our
experimental and simulation results and verify that the simulation tool can
capture the essential physics of this problem. Preliminary findings on
robustness to buckling provided by the bundling phenomenon and the efficiency
of a multi-flagellated soft robot are compared with the single-flagellated
counterparts. Observations were made on the coupling between geometry and
elasticity, which manifests itself in the propulsion of the robot by nonlinear
dependency on the rotational speed of the flagella.Comment: Supplementary Video: https://youtu.be/qevN1NovCZ
Untethered bio-inspired helical swimmer in channels
This study focuses on analyzing the effects of parameters such as helical pitch, helical wavelength, and frequency of rotations and diameter of channels on the measured velocity of helix and rotation rate of the body. The first stage of this study is macro design of robots with helical tails. The fundamentals of the design are mainly based on the criteria that affect the robots' motion. The second purpose of the thesis is applying the resistive force theory (RFT) to analyze the effects of swimming parameters and diameter of channels on the velocity of helix and rotation rate of body, analytically. This theoretical model is developed for six degree-of-freedom motion of the helix but two degree-of-freedom motion results are considered because only forward speed and body rotation rates are observable from experiments. The third stage of this study is analyzing the effect of swimming parameters and the diameter of channel on the swimming motion of the swimmer with helical tail by means of CFD (computational fluid dynamics) models. In the last stage, the experimental results are compared with RFT and CFD models
Humanities’ metaphysical underpinnings of late frontier scientific research
The behavior/structure methodological dichotomy as locus of scientific inquiry
is closely related to the issue of modeling and theory change in scientific explanation.
Given that the traditional tension between structure and behavior in scientific modeling is
likely here to stay, considering the relevant precedents in the history of ideas could help us
better understand this theoretical struggle. This better understanding might open up
unforeseen possibilities and new instantiations, particularly in what concerns the proposed
technological modification of the human condition. The sequential structure of this paper is
twofold. The contribution of three philosophers better known in the humanities than in the
study of science proper are laid out. The key theoretical notions interweaving the whole
narrative are those of mechanization, constructability and simulation. They shall provide
the conceptual bridge between these classical thinkers and the following section. Here, a
panoramic view of three significant experimental approaches in contemporary scientific
research is displayed, suggesting that their undisclosed ontological premises have deep
roots in the Western tradition of the humanities. This ontological lock between core
humanist ideals and late research in biology and nanoscience is ultimately suggested as
responsible for pervasively altering what is canonically understood as “human”
Microscopic motility of isolated E. coli flagella
The fluctuation-dissipation theorem describes the intimate connection between
the Brownian diffusion of thermal particles and their drag coefficients. In the
simple case of spherical particles, it takes the form of the Stokes-Einstein
relationship that links the particle geometry, fluid viscosity, and diffusive
behavior. However, studying the fundamental properties of microscopic
asymmetric particles, such as the helical-shaped propeller used by , has remained out of reach for experimental approaches due to the need
to quantify correlated translation and rotation simultaneously with sufficient
spatial and temporal resolution. To solve this outstanding problem, we
generated volumetric movies of fluorophore-labeled, freely diffusing, isolated
flagella using oblique plane microscopy. From these movies,
we extracted trajectories and determined the hydrodynamic propulsion matrix
directly from the diffusion of flagella via a generalized Einstein relation.
Our results validate prior proposals, based on macroscopic wire helices and low
Reynolds number scaling laws, that the average flagellum is a highly
inefficient propeller. Specifically, we found the maximum propulsion efficiency
of flagella is less than 5%. Beyond extending Brownian motion analysis to
asymmetric 3D particles, our approach opens new avenues to study the propulsion
matrix of particles in complex environments where direct hydrodynamic
approaches are not feasible.Comment: 6 pages, 4 figures, 9 supplemental sections, 7 supplemental figures,
3 supplemental movies *authors contributed equally and reserve the right to
change order for first authorshi
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