Versatile microrobotics using simple modular subunits

Cheang, U Kei; Meshkati, Farshad; Kim, Min Jun; Lee, Kyoungwoo; Fu, Henry

doi:10.1038/srep30472

Cited by 47 publications

(27 citation statements)

References 45 publications

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“…In the current work, tumor sensitization is performed indirectly through an external controlling and tracking system as shown in Fig. 1(a), such as an integrated device consisting of multiple pairs of electromagnetic coils to generate the rotating magnetic field to actuate the magnetic nanoswimmers [17], [18] and another coil to supply the polarizing magnetic field inducing the magnetic contrast associated with the nanoswimmers [12], [13]. Therefore, it is necessary that the in vivo biophysical gradients can be mapped to an externally measurable objective function by using nanoswimmers as a probe for analysis of the host environment.…”

Section: Externally Measurable Objective Functionsmentioning

confidence: 99%

“…IA,1 , which indicates a uniform magnetic field in the surveillance domain [17], [18] and is dependent on the iterative method described in Section IV. The next location of G 1 at time instant t (1) IT,1 is then updated according to:…”

Section: B Problem Formulationmentioning

confidence: 99%

“…Under an external magnetic field, the MNPs can magnetize and form chains that are flexible under time-varying magnetic fields via magnetohydrodynamics. A coil system was designed to actuate the nanoswimmers by applying a nearly uniform magnetic field through the Helmholtz configuration [17], [18]. One common external force can control large numbers of nanoswimmers to perform a complex task such as penetration of a tumor cell membrane for the selective release of a drug inside the cell [17], [19].…”

Section: Introductionmentioning

confidence: 99%

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Biosensing-by-Learning Direct Targeting Strategy for Enhanced Tumor Sensitization

Chen

Ali

Shi

et al. 2019

IEEE Trans.on Nanobioscience

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Objective: We propose a novel iterative-optimizationinspired direct targeting strategy (DTS) for smart nanosystems, which harness swarms of externally manipulable nanoswimmers assembled by magnetic nanoparticles (MNPs) for knowledgeaided tumor sensitization and targeting. We aim to demonstrate through computational experiments that the proposed DTS can significantly enhance the accumulation of MNPs in the tumor site, which serve as a contrast agent in various medical imaging modalities, by using the shortest possible physiological routes and with minimal systemic exposure.Methods: The epicenter of a tumor corresponds to the global maximum of an externally measurable objective function associated with an in vivo tumor-triggered biophysical gradient; the domain of the objective function is the tissue region at a high risk of malignancy; swarms of externally controllable magnetic nanoswimmers for tumor sensitization are modeled as the guess inputs. The objective function may be resulted from a passive phenomenon such as reduced blood flow or increased kurtosis of microvasculature due to tumor angiogenesis; otherwise, the objective function may involve an active phenomenon such as the fibrin formed during the coagulation cascade activated by tumortargeted "activator" nanoparticles. Subsequently, the DTS can be interpreted from the iterative optimization perspective: guess inputs (i.e., swarms of nanoswimmers) are continuously updated according to the gradient of the objective function in order to find the optimum (i.e., tumor) by moving through the domain (i.e., tissue under screening). Along this line of thought, we propose the computational model based on the gradient descent (GD) iterative method to describe the GD-inspired DTS, which takes into account the realistic in vivo propagation scenario of nanoswimmers.Results: By means of computational experiments, we show that the GD-inspired DTS yields higher probabilities of tumor sensitization and more significant dose accumulation compared to the "brute-force" search, which corresponds to the systemic targeting scenario where drug nanoparticles attempt to target a tumor by enumerating all possible pathways in the complex vascular network.Conclusion: The knowledge-aided DTS has potential to enhance the tumor sensitization and targeting performance remarkably by exploiting the externally measurable, tumor-triggered biophysical gradients.Significance: We believe that this work motivates a novel biosensing-by-learning framework facilitated by externally manipulable, smart nanosystems.

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Section: Externally Measurable Objective Functionsmentioning

confidence: 99%

Section: B Problem Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biosensing-by-Learning Direct Targeting Strategy for Enhanced Tumor Sensitization

Chen

Ali

Shi

et al. 2019

IEEE Trans.on Nanobioscience

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“…Other experimental work has developed more simplistic swimmer geometries, such as groups of magnetic beads [10][11][12][13][14]. These micro-robots are particularly relevant due to the ease with which they may be manufactured, but also because the symmetric nature of the sphere particularly lends it to theoretical and compu- * jbuzhar@g.clemson.edu † ptallap@clemson.edu tational modeling.…”

Section: Introductionmentioning

confidence: 99%

“…In experimental work, Cheang et al [18] demonstrated control of two geometrically similar but magnetically different swimmers using a single, uniform, rotating magnetic field. Later, Cheang et al [12] showed that such magnetic swimmers composed of beads can be deployed as modular sub-units, assembling and disassembling due to magnetic interactions. Recently the authors showed in simulation that the three-sphere artificial swimmer can be used to manipulate a passive spherical particle using the velocity field generated by the swimmer [20].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of groups of magnetically driven artificial microswimmers

Buzhardt

Tallapragada

2019

Phys. Rev. E

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Magnetically driven artificial microswimmers have the potential to revolutionize many biomedical technologies, such as minimally-invasive microsurgery, micro-particle manipulation, and localized drug delivery. However, many of these applications will require the controlled dynamics of teams of these micro-robots with minimal feedback. In this work, we study the motion and fluid dynamics produced by groups of artificial microswimmers driven by a torque induced through a uniform, rotating magnetic field. Through Stokesian dynamics simulations, we show that the swimmer motion produces a rotational velocity field in the plane orthogonal to the direction of the magnetic field's rotation, which causes two interacting swimmers to move in circular trajectories in this plane around a common center. The resulting over all motion is on a helical trajectory for the swimmers. We compare the highly rotational velocity field of the fluid to the velocity field generated by a rotlet, the point-torque singularity of Stokes flows, showing that this is a reasonable approximation on the time average. Finally, we study the motion of larger groups of swimmers and show that these groups tend to move coherently, especially when swimmer magnetizations are uniform. This coherence is achieved because the group center remains almost constant in the plane orthogonal to the net motion of the swimmers. The results in the paper will prove useful for controlling the ensemble dynamics of small collections of magnetic swimmers.

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Roads to Smart Artificial Microswimmers

Tsang

Demir

Ding

et al. 2020

Advanced Intelligent Systems

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Artificial microswimmers offer exciting opportunities for biomedical applications. The goal of these synthetics is to swim like natural micro‐organisms through biological environments and perform complex tasks such as drug delivery and microsurgery. Extensive efforts in the past several decades have focused on generating propulsion at the microscopic scale, which has engendered a variety of artificial microswimmers based on different physical and physicochemical mechanisms. Yet, these major advancements represent only the initial steps toward successful biomedical applications of microswimmers in realistic scenarios. A next step is to design “smart” microswimmers that can adapt their locomotion behaviors in response to environmental factors. Herein, recent progress in the development of microswimmers with intelligent behaviors is surveyed in three major areas: 1) adaptive locomotion across different media, 2) tactic behaviors in response to environment stimuli, and 3) multifunctional swimmers that can perform complex tasks. The emerging technologies and novel approaches used in developing these “smart” microswimmers, which enable them to display behaviors similar to biological cells, are discussed.

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Versatile microrobotics using simple modular subunits

Cited by 47 publications

References 45 publications

Biosensing-by-Learning Direct Targeting Strategy for Enhanced Tumor Sensitization

Biosensing-by-Learning Direct Targeting Strategy for Enhanced Tumor Sensitization

Dynamics of groups of magnetically driven artificial microswimmers

Roads to Smart Artificial Microswimmers

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