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. Those systems move intrinsically magnetic or magnetically tagged objects by inducing a magnetic torque or force. However, most of the materials found in nature are non-magnetic. Here, we report a novel ferrofluidic manipulator for automatic two-dimensional manipulation of non-magnetic objects floating on top of a ferrofluid. The manipulation system employs eight centimeter-scale solenoids, which can move non-magnetic particles floating on the air-liquid interface by deforming the air-ferrofluid interface. Using linear programming, we can control the motion of  non-magnetic particles with a predefined trajectory of a line, square, and circle with a precision of 57.4 +/ -33.6 um, 74 +/ -44.4 um , and 67.2 +/ -38.6 um, 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  .
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 non-magnetic. Here, we report a ferrofluidic manipulator for automatic two-dimensional manipulation of non-magnetic objects floating on top of a ferrofluid. The manipulation system employs eight centimeter-scale solenoids, which can move non-magnetic particles by deforming the air-ferrofluid interface. Using linear programming, we can control the motion of the non-magnetic particles with a predefined trajectory of a line, square, and circle with a precision of 25.1 +/ -19.5 um, 34.4 +/ -28.4 um and 33.4 +/ -26.6 um, 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 work shows a promising venue for the manipulation of living and non-living matter at the air-liquid interface .
R
Those
These
D
novel
D
floating on the air-liquid interface
A
the
R
57.4
25.1
R
-33.6 um, 74
-19.5 um, 34.4
R
-44.4 um , and 67.2
-28.4 um and 33.4
R
-38.6
-26.6
A
. This work shows a promising venue for the manipulation of living and non-living matter at the air-liquid interface