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One major challenge for untethered microscale mobile robotics is the manipulation of external objects. We work on various methods to manipulate micro-objects in both 2D and 3D. Such manipulation could be implemented in microfabrication and assembly of biological microobjects for medical application. The primary goal is the precise 6-DOF manipulation of complex parts in aqueous media.

Project Members:

Past Members:

Joshua Giltinan

Zhou Ye

Su Eun Chung

Xiaoguang Dong

Wenqi Hu

Hakan Ceylan

Eric Diller

Chytra Pawashe

Steven Floyd

Magnetic Micro-Gripper

Selected Research Results and Papers

Three-dimensional programmable assembly by untethered magnetic robotic microgrippers

Mobile sub-millimeter microrobots have demonstrated untethered motion and transport of cargo in remote, confined or enclosed environments. However, limited by simple design and actuation, they lack remotely-actuated on-board mechanisms required to perform complex tasks such as object assembly. A flexible patterned magnetic material which allows internal actuation, resulting in a mobile microgripper which is driven and actuated by magnetic fields, is introduced here. By remotely controlling the magnetization direction of each microgripper arm, a gripping motion which can be combined with locomotion for precise transport, orientation, and programmable three-dimensional assembly of micro-parts in remote environments is demonstrated. This allows the creation of out-of-plane 3D structures and mechanisms made from several building blocks. Using multiple magnetic materials in each microgripper, the addressable actuation of gripper teams for parallel, distributed operation is also demonstrated. These mobile microgrippers can potentially be applied to 3D assembly of heterogeneous meta-materials, construction of medical devices inside the human body, the study of biological systems in microfluidic channels, 3D microdevice prototyping or desktop microfactories.

E. Diller and M. Sitti, “Three-dimensional programmable assembly by untethered magnetic robotic micro-grippers,” Adv. Funct. Mater., vol. 24, no. 28, pp. 4397–4404, Jul. 2014.

Remotely-actuated untethered microgripper designs. a–c) Torque-based addressable microgripper. This microgripper is closed by application of a constant uniform magnetic field, which exerts a torque on each gripper arm. The “mobility magnet” acts to move the gripper as a mobile robotic device. c) A scanning electron microscope (SEM) image of a fabricated torque-based gripper. d–f) Force-based addressable microgripper. The gripping state is changed through the application of a large magnetic field pulse, which switches the ferrite magnet magnetization directions. This changes the arms from a repulsive to attractive state. The microgripper can be re-opened by applying a field pulse in the opposite direction. f) An SEM image of a fabricated force-based gripper. g) Magnetic coil system used to apply low and moderate fields of up to 22 kA m−1.

Untethered microrobotic coding of three-dimensional material composition

A method is used to code complex materials in three dimensions with tunable structural, morphological and chemical features using an untethered magnetic microrobot remotely controlled by magnetic fields. This strategy allows the microrobot to be introduced to arbitrary microfluidic environments for remote two- and three-dimensional manipulation. We demonstrate the coding of soft hydrogels, rigid copper bars, polystyrene beads and silicon chiplets into three-dimensional heterogeneous structures. We also use coded microstructures for bottom-up tissue engineering by generating cell-encapsulating constructs.

S. Tasoglu, E. Diller, S. Guven, et al., “Untethered microrobotic coding of three-dimensional material composition,” Nat. Commun., vol. 5, p. 3124, Jan. 2014.

Snapshots of manipulation stages are shown in each subfigure, with the completed structure shown in schematic form in (g) and (l), corresponding to panes (e) and (k), respectively.

Dynamic trapping and two-dimensional transport of swimming microorganisms using a rotating magnetic microrobot

Manipulation of microorganisms with intrinsic motility is a challenging yet important task for many biological and biomedical applications. Currently, such a task has only been accomplished using optical tweezers, while at the risk of averse heating and photodamage of the biological samples. Here, we proposed a new microrobotic approach for fluidic trapping and two-dimensional transportation of motile microorganisms near a solid surface in fluids. We demonstrated selective trapping and transportation of individual freely swimming multi-flagellated bacteria over a distance of 30 μm (7.5 body length of the carrier) on a surface, using the rotational flows locally induced by a rotating magnetic microparticle. Only a weak uniform magnetic field (<3 mT) was applied to actuate the microparticle. The microparticle can translate on a glass substrate by rotating at a speed of up to 100 μm s−1, while providing a fluidic force of a few to tens of pico-Newtons.

Z. Ye and M. Sitti, “Dynamic trapping and two-dimensional transport of swimming microorganisms using a rotating magnetic microrobot”, Lab on Chip 14, 2177-2182.

Trapping and transportation of a living motile bacterium

Selected Videos

Assembly of 3D four-bar linkage

Microrobotic coding of a heterogeneous structure

Transport of Swimming Microorganisms

Assembly of 3D four-bar linkage from polyurethane links by untethered magnetic robotic micro-grippers

Three-dimensional microrobotic coding of a heterogeneous structure consisting of PEG microgels which totally encase 100 μm diameter copper cylinders and 200 μm diameter polystyrene spheres.

Dynamic Trapping and Two-Dimensional Transport of Swimming Microorganisms Using a Rotating Magnetic  (2014)

List of Publications



Three-dimensional heterogeneous assembly of coded microgels using an untethered mobile micro-gripper

S. E. Chung, X. Dong, and M. Sitti

Lab on a Chip, in press.





Addressing of Micro-robot Teams and Non-contact Micro-manipulation

E Diller, Z Ye, J Giltinan, M Sitti

Small-Scale Robotics. From Nano-to-Millimeter-Sized Robotic Systems and Applications



Three‐Dimensional Programmable Assembly by Untethered Magnetic Robotic Micro‐Grippers

E Diller, M Sitti

Advanced Functional Materials 24, 4397–4404



Untethered micro-robotic coding of three-dimensional material composition

S Tasoglu, E Diller, S Guven, M Sitti, U Demirci

Nature Communications 5, DOI: 10.1038/ncomms4124



Three-dimensional robotic manipulation and transport of micro-scale objects by a magnetically driven capillary micro-gripper

J Giltinan, E Diller, C Mayda, M Sitti

Robotics and Automation (ICRA), 2014 IEEE International Conference on, 2077-2082



Dynamic Trapping and Two-Dimensional Transport of Swimming Microorganisms Using a Rotating Magnetic Micro-Robot

Z Ye, M Sitti

Lab on a Chip 14 (13), 2177-2182





Micro-manipulation using rotational fluid flows induced by remote magnetic micro-manipulators

Z Ye, E Diller, M Sitti

Journal of Applied Physics 112 (6), 064912



Two-dimensional autonomous microparticle manipulation strategies for magnetic microrobots in fluidic environments

C Pawashe, S Floyd, E Diller, M Sitti

Robotics, IEEE Transactions on 28 (2), 467-477





Rotating magnetic micro-robots for versatile non-contact fluidic manipulation of micro-objects

E Diller, Z Ye, M Sitti

Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International ...





Two-dimensional contact and noncontact micromanipulation in liquid using an untethered mobile magnetic microrobot

S Floyd, C Pawashe, M Sitti

Robotics, IEEE Transactions on 25 (6), 1332-1342



Funding Agency

National Robotics Initiative