Electric and Magnetic Field-Driven Dynamic Structuring for Smart Functional Devices

Abstract

The field of soft matter is rapidly growing and pushing the limits of conventional materials science and engineering. Soft matter refers to materials that are easily deformed by thermal fluctuations and external forces, allowing for better adaptation and interaction with the environment. This has opened up opportunities for applications such as stretchable electronics, soft robotics, and microfluidics. In particular, soft matter plays a crucial role in microfluidics, where viscous forces at the microscale pose a challenge to controlling dynamic material behavior and operating functional devices. Field-driven active colloidal systems are a promising model system for building smart functional devices, where dispersed colloidal particles can be activated and controlled by external fields such as magnetic and electric fields. This review focuses on building smart functional devices from field-driven collective patterns, specifically the dynamic structuring of hierarchically ordered structures. These structures self-organize from colloidal building blocks and exhibit reconfigurable collective patterns that can implement smart functions such as shape shifting and self-healing. The review clarifies the basic mechanisms of field-driven particle dynamic behaviors and how particle–particle interactions determine the collective patterns of dynamic structures. Finally, the review concludes by highlighting representative application areas and future directions.

Magnetically locked Janus particle clusters with orientation-dependent motion in AC electric fields

“…When a uniform AC field in the kHz frequency range is applied to a metallodielectric Janus particle within a liquid, the particle reorients such that the interface between the hemispheres aligns parallel with the field due to dielectrophoresis (DEP), yielding the greatest possible induced dipole moment. 46,47 After this reorientation, ions in solution accumulate preferentially at the surface of the metallic hemisphere, generating an induced charge cloud. At steady state, due to this induced charge cloud, fluid is drawn to the particle parallel to the field and ejected perpendicular to the field, away from the two hemispheres.…”

Advances in Nanoarchitectonics: A Review of “Static” and “Dynamic” Particle Assembly Methods

“…In the case of magnetic polarization, it is crucial to have magnetic materials present in either the particles or the medium. In contrast, electric polarization is less reliant on material selection due to the relatively modest difference in electric polarizability between most particles and an aqueous medium [ 141 ].…”

“…Crucially, these assembled clusters can generate non-uniform local fields of high intensity. These fields can attract neighboring particles through dielectrophoretic (or magnetophoretic) forces [ 141 ]. The combination of dipolar chaining and dielectrophoretic (or magnetophoretic) forces can lead to further assembly.…”

“…Multiple linear chains can evolve into close-packed crystalline structures under the continuous application of the same field. This synergy results in complex and organized structures [ 141 ].…”

Microrobots for Biomedicine: Unsolved Challenges and Opportunities for Translation

“…The revolutionary capabilities of microrobots have sparked a flurry of scientific research aimed at pushing the boundaries of biomedical research. Advancements in propulsion science, materials engineering, and fluid mechanics has enabled engineers and scientists to create microrobots with a suite of functionalities. − Such functions include transporting living cells and other biological cargo, moving through complex heterogeneous biological media, providing targeted and controlled drug delivery, , offering switchable control over modes of locomotion, , and enabling in vivo imaging . These advancements have fueled proof-of-concept studies in areas such as ocular drug delivery, in vitro fertilization, root canal prevention, and tumor treatment, among others.…”