Abstract
Manipulation of small-scale matter is a fundamental topic in micro and nanorobotics. Numerous magnetic robotic systems have been developed for the manipulation of microparticles in an ambient environment, liquid, as well as on the air-liquid interface. These systems move intrinsically magnetic or magnetically tagged objects by inducing a magnetic torque or force. However, most of the materials found in nature are nonmagnetic. Here, we report a ferrofluidic manipulator for automatic 2-D manipulation of nonmagnetic objects floating on top of a ferrofluid. The manipulation system employs 8-cm-scale solenoids, which can move nonmagnetic particles by deforming the air-ferrofluid interface. Using linear programming, we can control the motion of the nonmagnetic particles with a predefined trajectory of a line, square, and circle with a precision of 25.1 ± 19.5, 34.4 ± 28.4, and 33.4 ± 26.6 μm, respectively. The ferrofluidic manipulator is versatile with the materials and the shapes of the objects under manipulation. We have successfully manipulated particles made of polyethylene, polystyrene, a silicon chip, and poppy and sesame seeds. This article shows a promising venue for the manipulation of living and nonliving matter at the air-liquid interface.
Highlights
M AGNETIC field-driven manipulation of miniaturized robotic agents has attracted great research attention with a wide range of applications
We have recently reported the underlying physical mechanism of displacing and trapping micro and millimeter-sized particles at the air–paramagnetic liquid interface [33]
We have shown that nonmagnetic particles besides being pushed can be pulled, and eventually trapped at the air–paramagnetic liquid interface
Summary
M AGNETIC field-driven manipulation of miniaturized robotic agents has attracted great research attention with a wide range of applications. Manipulation of nonmagnetic objects on the air–liquid interfaces has been previously done using other methods, e.g., mechanical contact [28] and thermocapillary convention [29]. Magnetic liquids such as paramagnetic solutions and ferrofluids have found applications in microrobotics. We propose a ferrofluidic manipulator that can automatically manipulate nonmagnetic objects by controlling the curvature of the air–ferrofluid interface using eight solenoids. The ferrofluidic manipulator can manipulate nonmagnetic particles on the air–ferromagnetic interface along predefined trajectories, without contact with a solid tool, moving magnetic agent, coating the objects, or heating.
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