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# c12) United States Patent Roper et al. 

# (54) DEVICES FOR CHARGE-TITRATING PARTICLE ASSEMBLY, AND METHODS OF USING THE DEVICES 

(71) Applicant: HRL Laboratories, LLC, Malibu, CA (US) 

(72) Inventors: Christopher S Roper, Santa Monica, CA (US); Adam F. Gross, Santa Monica, CA (US) 

(73) Assignee: HRL Laboratories, LLC, Malibu, CA (US) 

( *) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 106 days. 

(21) Appl. No.: 15/241,661 

(22) Filed: Aug. 19, 2016 

(60) Provisional application No. 62/212,969, filed on Sep. 1, 2015, provisional application No. 62/213,044, filed on Sep. 1, 2015. 

(51) Int. Cl. 

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(52) U.S. Cl. CPC ....... BOJJ 1910046 (2013.01); COIF 1710062 (2013.01); COJG 4910045 (2013.01); 

( 58) Field of Classification Search CPC .............. B0lJ 19/0046; COIF 17/0062; C0lG 49/005; C0lG 49/02; C03B 7/10; 

## Related U.S. Application Data 

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# (10) Patent No.: US 9,981,240 Bl 

# May 29, 2018 (45) Date of Patent: 

## (56) References Cited 

Barnov et al., "Chemically induced self-assembly of spherical and anisotropic inorganic nanocrystals," J. Mater. Chem. 2011, 21, 16694. 

Primary Examiner - Jennifer Wecker 

(74) Attorney, Agent, or Firm - OConnor & Company 

## (57) ABSTRACT 

Methods to fabricate tightly packed arrays of nanoparticles are disclosed, without relying on organic ligands or a substrate. In some variations, a method of assembling par› ticles into an array comprises dispersing particles in a liquid solution; introducing a triggerable pH-control substance capable of generating an acid or a base; and triggering the pH-control substance to generate an acid or a base within the liquid solution, thereby titrating the pH. During pH titration, the particle-surface charge magnitude is reduced, causing the particles to assemble into a particle array. Other varia› tions provide a device for assembling particles into particle arrays, comprising a droplet-generating microfluidic region; a first-fluid inlet port; a second-fluid inlet port; a reaction microfluidic region, disposed in fluid communication with the droplet-generating microfluidic region; and a trigger source configured to trigger generation of an acid or a base from at least one pH-control substance contained within the reaction microfluidic region. 

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US009981240Bl 

## U.S. PATENT DOCUMENTS 

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## OTHER PUBLICATIONS 

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## 25 Claims, 20 Drawing Sheets 

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