Interface colloidal robotic manipulator
A magnetic colloidal system confined at the interface between two immiscible liquids and energized by an alternating magnetic field dynamically self-assembles into localized asters and arrays of asters. The colloidal system exhibits locomotion and shape change. By controlling a small external magnetic field applied parallel to the interface, structures can capture, transport, and position target particles.
1. An system for manipulating particles comprising:
a first liquid and a second liquid, the first and second liquid being immiscible;
magnetic microparticles dispersed at the interface of the two immiscible liquids; and
a magnetic source positioned to apply an alternating magnetic field to the dispersed magnetic microparticles.
2. The system of claim 1 , wherein the magnetic source is positioned to apply a uniform vertical magnetic field.
3. The system of claim 1 , wherein the frequency of the alternating magnetic field is between about 20 Hz and about 50 Hz.
4. The system of claim 1 , wherein the microparticles self-assemble to form a structure selected from the group consisting of asters, anti-asters, snakes, and dense clusters.
5. The system of claim 1 , further comprising an in-plane magnetic field.
6. The system of claim 5 , wherein the in-plane magnetic field is about 10 Oe to about 22 Oe.
7. The system of claim 5 , further comprising an aster formed by the magnetic microparticles, the aster having deformation from the in-plane magnetic field and a fluid flow providing locomotion to the aster.
8. The system of claim 5 , further comprising an array of asters self-assembled from the microparticles.
9. A self-assembling structure comprising:
a plurality of magnetic microparticles suspended at a liquid-liquid interface;
the plurality of magnetic microparticles arranged by dipole-dipole magnetic interactions with an external magnetic field; and
a deformation resulting in a non-symmetrical shape of the self-assembled structure.
10. The self-assembling structure of claim 9 , wherein the microparticles self-assemble to form a structure selected from the group consisting of asters, anti-asters, snakes, and dense clusters.
11. The self-assembling structure of claim 10 , wherein the self-assembled structure is an aster.
12. The self-assembling structure of claim 11 , wherein the aster has an associated toroidal hydrodynamic fluid flow.
13. A method for magnetic manipulation of self-assembled asters comprising:
suspending magnetic particles at an interface between two immiscible liquids;
energizing the ferromagnetic suspension by application of a vertically positioned alternating current magnetic field;
forming chains of magnetic particles;
rocking the chains of magnetic particles by action of the alternating current magnetic field;
deforming the interface; and
generating a hydrodynamic streaming flow associated with the chains of magnetic particles.
14. The method of claim 13 , wherein the chains of magnetic particles are organized as an aster.
15. The method of claim 14 , wherein fluid flow is from a periphery of the aster to the center.
16. The method of claim 14 , wherein fluid flow is from a center of the aster to the periphery, forming an anti-aster.
17. The method of claim 13 , wherein the hydrodynamic streaming forms jets perpendicular to the interface.
18. The method of claim 13 , wherein an in-plane static magnetic field is applied.