skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Field‐Directed Motion, Cargo Capture, and Closed‐Loop Controlled Navigation of Microellipsoids
Abstract Microrobots have the potential for diverse applications, including targeted drug delivery and minimally invasive surgery. Despite advancements in microrobot design and actuation strategies, achieving precise control over their motion remains challenging due to the dominance of viscous drag, system disturbances, physicochemical heterogeneities, and stochastic Brownian forces. Here, a precise control over the interfacial motion of model microellipsoids is demonstrated using time‐varying rotating magnetic fields. The impacts of microellipsoid aspect ratio, field characteristics, and magnetic properties of the medium and the particle on the motion are investigated. The role of mobile micro‐vortices generated is highlighted by rotating microellipsoids in capturing, transporting, and releasing cargo objects. Furthermore, an approach is presented for controlled navigation through mazes based on real‐time particle and obstacle sensing, path planning, and magnetic field actuation without human intervention. The study introduces a mechanism of directing motion of microparticles using rotating magnetic fields, and a control scheme for precise navigation and delivery of micron‐sized cargo using simple microellipsoids as microbots.  more » « less
Award ID(s):
1943986 2038305
PAR ID:
10532271
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Small
ISSN:
1613-6810
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Soft Matter)
    null (Ed.)
    Magnetic particles confined in microchannels can be actuated to perform translation motion using a rotating magnetic field, but their actuation in such a situation is not yet well understood. Here, the actuation of a ferromagnetic particle confined in square microchannels is studied using immersed-boundary lattice Boltzmann simulations. In wide channels, when a sphere is positioned close to a side wall but away from channel corners, it experiences a modest hydrodynamic actuation force parallel to the channel walls. This force decreases as the sphere is shifted toward the bottom wall but the opposite trend is found when the channel is narrow. When the sphere is positioned midway between the top and bottom channel walls, the actuation force decreases as the channel width decreases and can reverse its direction. These phenomena are elucidated by studying the flow and pressure fields in the channel-particle system and by analyzing the viscous and pressure components of the hydrodynamic force acting on different parts of the sphere. 
    more » « less
  2. ; (, Scientific Reports)
    Abstract Chemically coated micro/nanoparticles are often used in medicine to enhance drug delivery and increase drug up-take into specific areas of the body. Using a recently discovered spontaneous symmetry breaking propulsion mechanism, we demonstrate that chemically coated microparticles can swim through mucus solution under precise navigation and that certain functionalizations can dynamically change propulsion behavior. For this investigation biotin, Bitotin-PEG3-amine, and biotin chitosan were chemically functionalized onto the surfaces of magnetic microparticles using an avidin–biotin complex. These chemicals were chosen because they are used prolifically in drug delivery applications, with PEG and chitosan having well known mucoadhesive effects. Coated microparticles were then suspended in mucus synthesized from porcine stomach mucins and propelled using rotating magnetic fields. The relationship between different chemical coatings, microparticle velocity, and controllability were thoroughly explored and discussed. Results indicate that the biotinylated surface coatings altered the propulsion behavior of microparticles, with performance differences interlinked to both magnetic field properties and localized mucus properties. Precisely controlled drug carrying microparticles are envisioned to help supplant traditional drug delivery methods and enhance existing medical techniques utilizing micro/nanoparticles. 
    more » « less
  3. ; ; ; (, Advanced Intelligent Systems)
    Planar magnetic microswimmers bear great potential for in vivo biomedical applications as they can be mass‐produced at minimal costs using standard photolithography techniques. Therefore, it is central to understand how to control their motion. This study examines the propulsion of planar V‐shaped microswimmers in an aqueous solution powered by a conically rotating magnetic field and compares the experimental results with theory. Propulsion is investigated upon altering the cone angle of the driving field. It is shown that a V‐shaped microswimmer magnetized along its symmetry axis exhibits unidirectional in‐sync propulsion with a constant (frequency‐independent) velocity in a limited band of actuation frequencies. It is also demonstrated that the motion of individual and multiple in‐plane magnetized planar microswimmers in a conically rotating field can be efficiently controlled. 
    more » « less
  4. ; (, Physica Scripta)
    Abstract We study the classical motion of a charged particle in presence of an inductively increasing time-dependent magnetic field as the one created inside a resistor-inductor series circuit driven by a voltage source. The inductor is treated as an infinite solenoid. In such a scenario, the expression for the time-dependent magnetic field generated when the circuit is turned on can be easily derived. We consider the case study of two-dimensional motion since the generalization to three-dimensions is elementary. The resulting differential equations for the two-dimensional motion of the charged particle are solved by using a particular method which relies in deployment of complex variables. The ensuing motion has interesting features that highlight the challenges faced in studies of charged particles in a time-dependent magnetic field. This study has applications in magnetic plasma confinement, where understanding charged particle dynamics in time-varying magnetic fields helps optimize stability and energy retention in fusion devices. 
    more » « less
  5. ; ; ; (, Advanced Functional Materials)
    Abstract Recent progress in artificial nanomachines offers promising solutions to grand challenges in biochemical delivery and diagnostics. In this work, advances of micro/nanomachines made of synthesized micro/nanostructures for applications in delivery and detection of biomolecules are reviewed, along with a discussion of pros and cons of each type of machine. The review of micro/nanomachines is categorized according to their working mechanisms, including motion actuation realized by magnetic, electric, and acoustic fields and chemical reactions. The developments of micro/nanomachines are discussed in depth in the fabrication, propulsion, and motion control, loading and releasing of micro/nanosubstances, and biochemical sensing. The rapid development of man‐made miniaturized machines paves the road toward future intelligent nanorobots and nanofactories that can revolutionize society. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email