# US 9,750,436 B1 · Method for detecting fingerprints

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- Number: US 9,750,436 B1
- Document ID: US9750436B1
- Status: Granted
- Kind: B1
- Application number: 14/682,984
- Filed: 2015-04-09
- Granted: 2017-09-05
- Earliest claimed: 2014-04-11
- Assignees: Air Science USA LLC
- Applicants: Air Science USA LLC
- Inventors: Paul Chambre
- Web page: https://patentgrep.com/patent/US9750436B1

## CPC

- A61B 5/1172: using fingerprinting
- C08F 122/32: Alpha-cyano-acrylic acid; Esters thereof
- C08J 3/12: Powdering or granulating
- C08J 2335/04: Homopolymers or copolymers of nitriles (C08J2335/06, C08J2335/08 take precedence)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

Process for producing powdered polycyanoacrylate polymer by charging a reaction vessel with an aqueous mist, dripping a 2-cyanoacrylate into the reaction vessel, allowing the resulting reaction mass (polycyanoacrylate polymer) to cool, removing the polycyanoacrylate polymer from the reaction vessel, drying it, and pulverizing the dry solid into a powder. Powdered polycyanoacrylate polymer having a particle diameter in the range of from 1 to 200 microns. The particle size and shape herein contribute to uniform distribution of fumes during fingerprint capture. A high level of accuracy in fingerprint detection is provided among three distinct levels which include: (a) first level detection from ridge flow patterns such as whorl or loop; (b) second level detection from ridge flow singularities such as ridge endings and bifurcations; (c) and third level detection from pore configuration.

## Claims

### Claim 1

A method for detecting fingerprints, said method comprising:
vaporizing a powdered polycyanoacrylate polymer wherein more than 95% of the particle mass comprises particles having a particle diameter in the range of from 1 to 200 microns in the vicinity of a substrate suspected of containing fingerprints; and
allowing the vaporized polycyanoacrylate to settle onto the substrate suspected of containing the fingerprints.

### Claim 2

A method for detecting fingerprints, said method comprising:
vaporizing a powdered polycyanoacrylate polymer having one or more of the following particle size characteristics: (i) at least 50 weight-% of the powder particles have a feret length of from 20 to 80 nanometers; (ii) at least 50 weight-% of the powder particles have a feret width of from 10 to 40 nanometers; and (iii) at least 50 weight-% of the powder particles have a rectangularity ranging from 60 to 75 in the vicinity of a substrate suspected of containing fingerprints; and
allowing the vaporized polycyanoacrylate to settle onto the substrate suspected of containing the fingerprints.

### Claim 3

A method for detecting fingerprints, said method comprising:
vaporizing a powdered polycyanoacrylate produced by a process comprising: (a) charging a reaction vessel with a mist comprising water; (b) adding methyl or ethyl 2-cyanoacrylate to the reaction vessel by dripping it into the water mist, thereby producing an exothermic reaction, while decreasing the rate of addition of methyl or ethyl 2-cyanoacrylate or temporarily halting addition of the methyl or ethyl 2-cyanoacrylate if the temperature in the reaction vessel becomes too high for uniform polymerization; (c) once all of the methyl or ethyl 2-cyanoacrylate has been added, allowing the reaction mass to cool; (d) removing the polycyanoacrylate polymer from the reaction vessel; (e) drying the polycyanoacrylate polymer to provide a dry solid polycyanoacrylate polymer; and (f) pulverizing the dry solid into a powder in the vicinity of a substrate suspected of containing fingerprints; and
allowing the vaporized polycyanoacrylate to settle onto the substrate suspected of containing the fingerprints.

### Claim 4 (depends on 1)

The method for detecting fingerprints of claim 1, wherein said powdered polycyanoacrylate polymer has a median particle diameter of approximately 20 microns and a mean particle diameter of approximately 60 microns.

### Claim 5 (depends on 2)

The method for detecting fingerprints of claim 2, wherein said powdered polycyanoacrylate polymer has all three of characteristics (i), (ii), and (iii).