Lorentz Force-Driven Autonomous Janus Swimmers

Abstract

Autonomous swimmers have been intensively studied in recent years due to their numerous potential applications in many areas ranging from biomedicine to environmental remediation. Their motion is based either on different self-propulsion mechanisms or on the use of various external stimuli. Herein, the synergy between the ion flux around self-electrophoretic Mg/Pt Janus swimmers and an external magnetic field is proposed as an efficient alternative mechanism to power swimmers on the basis of the resulting Lorentz force. A strong magnetohydrodynamic effect is observed due to the orthogonal combination of magnetic field and spontaneous ionic currents, leading to an increase of the swimmer speed by up to 2 orders of magnitude. Furthermore, the trajectory of the self-propelled swimmers can be controlled by the orientation of the magnetic field, due to the presence of an additional torque force caused by a horizontal cation flux along the swimmer edges, resulting in predictable clockwise or anticlockwise motion. In addition, this effect is independent of the swimmer size, since a similar type of rotational motion is observed for macro- and microscale objects.

Magnetic Nanomotors in Emulsions for Locomotion of Microdroplets

“…The world of micro-/nanomotors is extremely diverse. − The wide research interest in such systems is due to a variety of applied problems, which can be solved with their use in fields such as medicine, − ecology, − elaboration of sensors, − degradation of antibiotics, and antibiotic therapy. , Nowadays, many micro-/nanomotors are under study: Janus micro- and nanomotors, − helical micromotors, tubular micromotors, self-propelled droplets, − biohybrid robotics, and micromotors on the base of metal oxides. − The motion of micro-/nanomotors can be due to different factors such as light, − chemical reactions, − and effects of acoustic, electric, or magnetic fields. − In the case of using a magnetic field, micro-/nanomotors can convert the energy of magnetic field into mechanical energy. Significant research interest to this method of micro-/nanomotor locomotion is because a low-intensity magnetic field is harmless for living organisms.…”

Refillable Fuel-Loading Microshell Motors for Persistent Motion in a Fuel-Free Environment

“…4 Similar to biological motors, artificial micro-/nanomotors also harvest environmental energy to move and accomplish on-demand tasks. The driving force of micro-/nanomotors comes from the energy conversion of chemical/biochemical reactions, 5,6 acoustic waves, 7 light, 8 magnetic, 9 electric fields, 10 or their combined field. 11 To date, various micro-/nanomotors of different shapes have been prepared from different materials.…”

“…Similar to biological motors, artificial micro-/nanomotors also harvest environmental energy to move and accomplish on-demand tasks. The driving force of micro-/nanomotors comes from the energy conversion of chemical/biochemical reactions, , acoustic waves, light, magnetic, electric fields, or their combined field . To date, various micro-/nanomotors of different shapes have been prepared from different materials. − Unfortunately, most micro-/nanomotors need to be present in energy supply surroundings, for example, existence in fuel solutions of H 2 O 2 , N 2 H 4 , and Ag + , or with real-time stimuli of external energy sources, − which greatly limit their applications, especially in the biological field.…”

Autonomous Chiral Microswimmers with Self‐mixing Capabilities for Highly Efficient Enantioselective Synthesis

“…The rational design of micro‐ and nano‐swimmers has gained considerable attention during the last decade, [12–21] due to the increasing number of potential applications in biomedicine, [22–27] environmental remediation, [28, 29] (bio)sensing [30, 31] and to mimic collective behavior of microorganisms [32–34] . The motion of these devices can be powered either by applying external stimuli (light, ultrasound, and magnetic or electric fields) or by the conversion of chemical energy into motion via different mechanisms, such as Marangoni effect, self‐diffusiophoresis, self‐electrophoresis and bubble propulsion [35–45] . Recently, the use of self‐propelled swimmers as microreactors, coupling the autonomous motion with the possibility to convert a substance in loco into a desired product, has been extensively studied.…”

“…[32][33][34] The motion of these devices can be powered either by applying external stimuli (light, ultrasound, and magnetic or electric fields) or by the conversion of chemical energy into motion via different mechanisms, such as Marangoni effect, self-diffusiophoresis, self-electrophoresis and bubble propulsion. [35][36][37][38][39][40][41][42][43][44][45] Recently, the use of self-propelled swimmers as microreactors, coupling the autonomous motion with the possibility to convert a substance in loco into a desired product, has been extensively studied. Such dynamic processes, also known as "chemistry on the fly", [46][47][48] are based on the synergy between an efficient propulsion and a specific surface functionalization, allowing these mobile platforms to move and actively mix reactants in the solution, combined with a high intrinsic surface reactivity towards the target molecules.…”