Methods and systems for optical control of metal particles with thermophoresis

Patent metadata

Field	Value
Publication number	US-11060976-B2
Application number	US-201716331249-A
Country	US
Kind code	B2
Filing date	Sep 8, 2017
Priority date	Sep 9, 2016
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

Disclosed herein are methods comprising illuminating a first location of a plasmonic substrate with electromagnetic radiation, wherein the electromagnetic radiation comprises a wavelength that overlaps with at least a portion of the plasmon resonance energy of the plasmonic substrate. The plasmonic substrate can be in thermal contact with a liquid sample comprising a plurality of metal particles and a surfactant, the liquid sample having a first temperature. The methods can further comprise generating a confinement region at a location in the liquid sample proximate to the first location of the plasmonic substrate, wherein at least a portion of the confinement region has a second temperature that is greater than the first temperature such that the confinement region is bound by a temperature gradient. The methods can further comprise trapping at least a portion of the plurality of metal particles within the confinement region.

First claim

What is claimed is:

1. A method comprising:
illuminating a first location of a plasmonic substrate with electromagnetic radiation at a power density of 0.1 mW/μm2 or less;
wherein the electromagnetic radiation comprises a wavelength that overlaps with at least a portion of the plasmon resonance energy of the plasmonic substrate such that the plasmonic substrate converts at least a portion of the electromagnetic radiation into thermal energy by plasmon-enhanced photothermal effects; and
wherein the plasmonic substrate is in thermal contact with a liquid sample comprising a plurality of capped metal particles and a surfactant, the liquid sample having a first temperature;
wherein the plurality of capped metal particles comprise a plurality of metal particles capped with a capping material;
wherein the capping material comprises a cationic material or an anionic material, such that the plurality of capped metal particles have a surface charge;
wherein the surfactant comprises a cationic surfactant or an anionic surfactant, such that the surfactant has a charge;
wherein the surface charge of the plurality of capped metal particles and the charge of the surfactant are both positive or are both negative; thereby,
generating a first confinement region at a location in the liquid sample proximate to the first location of the plasmonic substrate by plasmon-enhanced photothermal effects, wherein at least a portion of the first confinement region has a second temperature that is greater than the first temperature such that the first confinement region is bound by a temperature gradient;
repulsing at least a portion of the surfactant from the first confinement region via thermophoresis, such that the surfactant has a nonuniform concentration in the liquid sample, thereby inducing a thermoelectric field within the liquid sample; and
trapping at least a portion of the plurality of capped metal particles within the first confinement region via thermophoresis and a thermoelectric effect, said portion of the plurality of capped metal particles being a trapped portion of the plurality of capped metal particles.

2. The method of claim 1 , wherein the electromagnetic radiation is provided by a light source and the light source is a laser.

3. The method of claim 2 , wherein the light source is configured to illuminate a mirror and the mirror is configured to reflect the electromagnetic radiation from the light source to illuminate the first location of the plasmonic substrate.

4. The method of claim 3 , wherein the mirror comprises a digital micromirror device.

5. The method of claim 1 , wherein the plasmonic substrate comprises a plurality of plasmonic particles and the plurality of plasmonic particles comprise a metal selected from the group consisting of Au, Ag, Al, and combinations thereof.

6. The method of claim 1 , wherein the capping material and the surfactant are the same material.

7. The method of claim 1 , wherein the surfactant is selected from the group consisting of cetrimonium bromide (CTAB), cetrimonium chloride (CTAC), sodium dodecyl sulfate (SDS), and combinations thereof.

8. The method of claim 1 , wherein the surfactant has a concentration in the liquid sample and the concentration of the surfactant in the liquid sample is above the critical micelle concentration of the surfactant, such that the surfactant forms a plurality of surfactant micelles in the liquid sample.

9. The method of claim 1 , wherein the trapped portion of the plurality of capped metal particles is one capped metal particle.

10. The method of claim 1 , wherein the trapped portion of the plurality of capped metal particles is further trapped by an electrostatic force, a van der Waals force, or combinations thereof.

11. The method of claim 1 , further comprising illuminating a second location of the plasmonic substrate thereby:
generating a second confinement region at a location in the liquid sample proximate to the second location of the plasmonic substrate by plasmon-enhanced photothermal effects, wherein at least a portion of the second confinement region has a third temperature that is greater than the first temperature such that the second confinement region is bound by a temperature gradient; and
translocating the trapped portion of the plurality of capped metal particles from the first confinement region to the second confinement region, trapping at least a second portion of the plurality of capped metal particles within the second confinement region, or a combination thereof.

12. The method of claim 11 , wherein:
the plasmonic substrate is translocated to illuminate the second location;
the electromagnetic radiation is provided by a light source and:
the light source is translocated to illuminate the second location; or
the light source is configured to illuminate a mirror and the mirror is configured to reflect the electromagnetic radiation from the light source to illuminate the plasmonic substrate, and the mirror is translocated to illuminate the second location;

or a combination thereof.

13. The method of claim 1 , wherein the plasmonic substrate comprises a portion of a substrate, the substrate further comprising a non-plasmonic portion and wherein the substrate is in thermal contact with the liquid sample, wherein the method further comprises illuminating a location of the non-plasmonic portion of the substrate, thereby:
generating a second confinement region at a location in the liquid sample proximate to the location of the non-plasmonic portion of the substrate, wherein at least a portion of the second confinement region has a third temperature that is greater than the first temperature such that the second confinement region is bound by a temperature gradient; and
translocating the trapped portion of the plurality of capped metal particles from the first confinement region to the second confinement region.

14. The method of claim 13 , wherein:
the substrate is translocated to illuminate the location of the non-plasmonic portion of the substrate;
the electromagnetic radiation is provided by a light source and:
the light source is translocated to illuminate the location of the non-plasmonic portion of the substrate; or
the light source is configured to illuminate a mirror and the mirror is configured to reflect the electromagnetic radiation from the light source to illuminate the substrate, and the mirror is translocated to illuminate the location of the non-plasmonic portion of the substrate;

or a combination thereof.

15. The method of claim 13 , wherein the non-plasmonic portion of the substrate comprises glass, quartz, silicon dioxide, a polymer, or a combination thereof.

16. The method of claim 1 , wherein the trapping of the trapped portion of the plurality of capped metal particles is reversible.

17. The method of claim 1 , further comprising removing the illumination, such that the temperature of the liquid sample equilibrates, thereby:
eliminating the first confinement region;
redispersing the surfactant in the liquid sample, such that the surfactant has a uniform concentration in the liquid sample; and
releasing the trapped portion of the plurality of capped metal particles.

Assignees

• Univ Texas

Inventors

• Zheng Yuebing
• Lin Linhan
• Peng Xiaolei

Classifications

• G01N21/64

  Fluorescence; Phosphorescence · CPC title

• G01N21/658 Primary

  enhancement Raman, e.g. surface plasmons · CPC title

• G01N21/01

  Arrangements or apparatus for facilitating the optical investigation · CPC title