US009981240Bl  (10)  Patent No.:  US 9,981,240 Bl  May 29, 2018  (45)  Date of Patent:  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.  (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;  Barnov et al., "Chemically induced self-assembly of spherical and  anisotropic inorganic nanocrystals," J. Mater. Chem. 2011, 21,  16694.  (Continued)  (Continued)  Primary Examiner  - Jennifer Wecker  (74)  Attorney, Agent, or Firm  - OConnor & Company  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.  (Continued)  (Continued)  (Continued)  BOJJ 19100  COJG 49102  (2006.01)  (2006.01)  5,534,461 A  5,591,535 A  7/1996 Kuwajima  l/ 1997 Hisano et al.  (56)  References Cited  U.S. PATENT DOCUMENTS  Related U.S. Application Data  (57)  ABSTRACT  OTHER PUBLICATIONS  25 Claims, 20 Drawing Sheets  Fluid 2  *See F!G. 4B  +:.-.  •, ----Trigger source 