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. 2021 Apr 7;12(4):410.
doi: 10.3390/mi12040410.

Magnetic Driven Two-Finger Micro-Hand with Soft Magnetic End-Effector for Force-Controlled Stable Manipulation in Microscale

Dan Liu  1 , Xiaoming Liu  1 , Pengyun Li  1 , Xiaoqing Tang  1 , Masaru Kojima  2 , Qiang Huang  1 , Tatsuo Arai  1   3
Affiliations

Magnetic Driven Two-Finger Micro-Hand with Soft Magnetic End-Effector for Force-Controlled Stable Manipulation in Microscale

Dan Liu et al. Micromachines (Basel). .

Abstract

In recent years, micromanipulators have provided the ability to interact with micro-objects in industrial and biomedical fields. However, traditional manipulators still encounter challenges in gaining the force feedback at the micro-scale. In this paper, we present a micronewton force-controlled two-finger microhand with a soft magnetic end-effector for stable grasping. In this system, a homemade electromagnet was used as the driving device to execute micro-objects manipulation. There were two soft end-effectors with diameters of 300 μm. One was a fixed end-effector that was only made of hydrogel, and the other one was a magnetic end-effector that contained a uniform mixture of polydimethylsiloxane (PDMS) and paramagnetic particles. The magnetic force on the soft magnetic end-effector was calibrated using an atomic force microscopy (AFM) probe. The performance tests demonstrated that the magnetically driven soft microhand had a grasping range of 0-260 μm, which allowed a clamping force with a resolution of 0.48 μN. The stable grasping capability of the magnetically driven soft microhand was validated by grasping different sized microbeads, transport under different velocities, and assembly of microbeads. The proposed system enables force-controlled manipulation, and we believe it has great potential in biological and industrial micromanipulation.

Keywords: force-controlled; magnetically driven; micromanipulation; micronewton; stable grasping.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic of the magnetically driven soft microhand. (a) Schematic of the manipulation system. (b) The fabrication method based on injection molding. (c) Illustration of the hydrogel skin formation onto the surface of the magnetic end-effector.
Figure 2
Figure 2
System setup.
Figure 3
Figure 3
Finite element simulation of magnetic field distribution and tip displacement.
Figure 4
Figure 4
Schematic of the magnetic driven soft end-effector calculation. (a) Stiffness calibration of the magnetic end-effector. (b) Magnetic force measurement of the magnetic end-effector under an applied magnetic field.
Figure 5
Figure 5
Forces acting on a microobject.
Figure 6
Figure 6
Motion analysis of the magnetic end-effector under a magnetic field. (a) The relationship between the magnetic field, displacement, and magnetic force; (b) The step response to the current of 8A.
Figure 7
Figure 7
Micromanipulation of microbeads: (a) grasping microbeads with diameters of 50, 100, 200, and 300 μm; (b) Alignment; (c) Clamping microbeads; (d) Translating microbeads; (e) Releasing microbeads.
Figure 8
Figure 8
The relationship between clamping force and success rate of grasping microbeads.
Figure 9
Figure 9
Assembly of the 2D pattern. (a) Optical microscopy image of collected 15 microbeads. (b) The assembled triangle pattern.
See this image and copyright information in PMC

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