Self-assembly of magnetic colloids under unsteady fields Camacho Villar, Guillermo Morillas Medina, José Rafael Vicente Álvarez-Manzaneda, Juan De This work was supported by projects PID2022-138990NB-I00 and TED2021.129384B.C22 funded by MCIN/AEI/10.13039/501100011033 and by EU NextGenerationEU/PRTR. G. C. acknowledges the financial support by the FPU20/04357 fellowship. J. R. M. acknowledges the financial support by (EFST)-H2020-MSCA–IF–2020 (Grant 101030666) fellowship. The use of magnetic fields offers an external, versatile way of controlling self-assembly of colloids. This review provides an exhaustive overview of unsteady fields that can vary in one, two, or three dimensions of space, as a powerful tool to direct the self-assembly of magnetic colloids into structures with tunable properties. Unlike steady fields, unsteady (nonstationary) fields can overcome the limitations of classical dipolar interactions, leading to a much wider range of structures, ranging from dense crystalline aggregates to 3D spanning networks, or dynamic clusters. The ability to precisely control the amplitude, frequency, and field direction allows for finetuning the interplay of interparticle forces, resulting in controllable assembly pathways. This review analyzes how different types of unsteady fields influence the morphology and dynamics of the self-assembled structures. Key parameters, such as the Mason number, are discussed to characterize the governing driving forces, and potential applications are highlighted. 2025-05-07T06:29:47Z 2025-05-07T06:29:47Z 2025-05-06 journal article Camacho Villar, Guillermo; Morillas Medina, José Rafael y Vicente Álvarez-Manzaneda, Juan. DeCurrent Opinion in Colloid & Interface Science 2025, 76:101903. https://doi.org/10.1016/j.cocis.2025.101903 https://hdl.handle.net/10481/103968 10.1016/j.cocis.2025.101903 eng info:eu-repo/grantAgreement/EC/H2020/101030666 http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier