Dumbbell Fluidic Tweezers for Dynamical Trapping and Selective Transport of Microobjects

Abstract

Mobile microvortices generated by rotating nickel (Ni) nanowires (NW) have been reported as capable of inducing fluidic trapping that can be precisely focused and translated to manipulate microobjects. Here, a new design for significantly enhanced fluidic trapping is reported, which is a dumbbell (DB)-shaped magnetic actuator, assembled by a Ni NW and two polystyrene microbeads. In contrast to the single mode of tumbling trapping possessed by Ni NW, the magnetic dumbbell is able to perform dynamical trapping and implement on-demand transport of microobjects in three modes, i.e., tumbling, wobbling, and rolling. Experiments are conducted to demonstrate the robustness and efficacy of the fluidic trap by the DB actuator. And simulations using a finite element model compare the fluidic traps induced by NW and DB, followed by further discussion on the actuation and transport efficiency of NW and DB fluidic tweezers (FT). At last, some practical issues regarding the application of DB FT are addressed.

Programmable Locomotion Mechanisms of Nanowires with Semihard Magnetic Properties Near a Surface Boundary

“…[23][24][25] Barbot et al have recently manufactured helical microswimmers with conical heads that switch between rolling, spintop motion, and corkscrew swimming by adjusting both the direction and the frequency of the rotating magnetic field. 26 Recent studies on small-scale robotic structures, which are closely related to ours in terms of configuration, are those reported by Zhou et al and Mair et al 19,27 Zhou et al reported a motion change of a dumbbell-like magnetic microstructure, fabricated by assembling two polystyrene microbeads to the tips of a magnetic nanowire. 27 They demonstrated that the microstructure "walks" on a solid boundary under a rotating magnetic field.…”

“…26 Recent studies on small-scale robotic structures, which are closely related to ours in terms of configuration, are those reported by Zhou et al and Mair et al 19,27 Zhou et al reported a motion change of a dumbbell-like magnetic microstructure, fabricated by assembling two polystyrene microbeads to the tips of a magnetic nanowire. 27 They demonstrated that the microstructure "walks" on a solid boundary under a rotating magnetic field. However, the change of motion of the microstructure was due to its weight-imbalance by a slight variation in the size of the microbeads.…”

Irreversible hydrodynamic trapping by surface rollers

“…In what is perhaps the simplest configuration suitable for the manipulation of objects in a fluid at small scales, rotating nanowires have been shown to be capable of trapping and transporting small particles within hydrodynamic vortices, as shown in Fig. 1a [23,26,37].…”

Hypersonic‐Induced 3D Hydrodynamic Tweezers for Versatile Manipulations of Micro/Nanoscale Objects

“…Because of their promising potential in micro/nanoscale manipulation and biomedical applications, microrobots have attracted a lot of research interest in the last decade. [1][2][3][4][5][6] One key function in microrobot is to precisely trap, manipulate, and remote transfer targeted objects (cells, micro/nanoscale carriers, etc.) in a size-compatible environment (micro/nano channels, blood vessels, stomach, etc.).…”