Abstract
Manipulation and navigation of micro and nanoswimmers in different fluid environments can be achieved by chemicals, external fields, or even motile cells. Many researchers have selected magnetic fields as the active external actuation source based on the advantageous features of this actuation strategy such as remote and spatiotemporal control, fuel-free, high degree of reconfigurability, programmability, recyclability, and versatility. This review introduces fundamental concepts and advantages of magnetic micro/nanorobots (termed here as “MagRobots”) as well as basic knowledge of magnetic fields and magnetic materials, setups for magnetic manipulation, magnetic field configurations, and symmetry-breaking strategies for effective movement. These concepts are discussed to describe the interactions between micro/nanorobots and magnetic fields. Actuation mechanisms of flagella-inspired MagRobots (i.e., corkscrew-like motion and traveling-wave locomotion/ciliary stroke motion) and surface walkers (i.e., surface-assisted motion), applications of magnetic fields in other propulsion approaches, and magnetic stimulation of micro/nanorobots beyond motion are provided followed by fabrication techniques for (quasi-)spherical, helical, flexible, wire-like, and biohybrid MagRobots. Applications of MagRobots in targeted drug/gene delivery, cell manipulation, minimally invasive surgery, biopsy, biofilm disruption/eradication, imaging-guided delivery/therapy/surgery, pollution removal for environmental remediation, and (bio)sensing are also reviewed. Finally, current challenges and future perspectives for the development of magnetically powered miniaturized motors are discussed.
Highlights
Many species in nature, such as magnetotactic bacteria, birds, bats, butterflies, lobsters, and salmon, can fly or swim over a long distance by perceiving navigation cues from geomagnetic fields
The locomotion of nanoscale and microscale objects in a predefined path by the navigation of magnetic fields,[1−4] which are mainly generated by moving charges and magnetic materials, has drawn extensive attention owing to their tremendous potential for applications in biomedicine and environmental remediation
In magnetic actuation systems based on electromagnets, magnetic fields are generated from flowing currents through coils
Summary
Many species in nature, such as magnetotactic bacteria, birds, bats, butterflies, lobsters, and salmon, can fly or swim over a long distance by perceiving navigation cues from geomagnetic fields. Programmability refers to the ability to manipulate the components of the MagRobots in terms of their shape, magnetic shape, magnetic anisotropy,[61] and crystalline anisotropy to achieve a specific motion mode, position, or orientation when magnetic fields are applied.[62,63] For example, the orientation of a magnetic composite-based structure can be programmed by suitably aligning the particles within the composite matrix.[60] Specific shape-morphing small-scale systems can be designed to exhibit both reconfigurability and programmability.[64] (iv) Recyclability of magnetic materials: after micro/nanorobots have completed their tasks, the separation and recycling of introduced foreign matter from water, biological fluids, or even tissues might be necessary in terms of biosafety and biocompatibility. The easy magnetization axis can be programmed, for instance, by orienting magnetic nanostructures with a matrix of a composite component or by premagnetizing a material in a specific direction: 2. INTERATIONS BETWEEN MICRO/NANOROBOTS AND MAGNETIC FIELDS
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
