Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Inverse Fingerprints on Paper

05.11.2012
Visualization of Latent Fingermarks by Nanotechnology: Reversed Development on Paper: A Possible Remedy to the Variation in Sweat Composition

Paper is one of the surfaces most commonly tested for fingerprints in forensics. Unfortunately, it is particularly difficult to make fingerprints on paper visible. In the journal Angewandte Chemie, Israeli scientists have now introduced a new method developed specifically for use on paper.



It produces a “negative” of the fingerprint and is, in contrast to conventional methods, independent of the composition of the sweat residue left behind.

In many criminal cases, paper evidence plays an important role and it would be useful to know through whose hands checks, documents, or paper currency have passed. Studies have shown that only about half of the fingerprints present on paper can be made sufficiently visible. The main reason that this does not work consistently seems to be the highly variable composition of the sweat left behind on the paper.

A team led by Daniel Mandler and Joseph Almog at the Hebrew University of Jerusalem has now developed a procedure that avoids these problems. It involves a sort of inversion of an established method in which gold nanoparticles are first deposited onto the invisible fingerprints, followed by elemental silver, similar to the development of a black and white photograph.

In the conventional technique, the gold particles get stuck to components of the sweat in fingerprints. In contrast, the gold nanoparticles in the new method stick directly to the paper, not the sweat. This technique uses the sebum from the fingerprints, which effectively shields the paper beneath it from the gold nanoparticles. Treatment with a developer containing silver, which turns the areas with gold on them black, results in a negative image of the fingerprint.

The secret to the success of these researchers is a special bifunctional reagent. The head of this molecule is an acylpyridazine group, which can bind to cellulose. The tail is made of hydrocarbon chains with a sulfur-containing group at the end, which binds to gold and attaches the molecule to the surface of the gold nanoparticles. When gold particles coated with these molecules are deposited onto paper with a fingerprint on it, the heads bind to the cellulose in the paper, avoiding the fat-containing lines.

Because only the fatty components of the fingerprints are used, the possibly unfavorable composition of the sweat in the fingerprint plays no role in this method. This technique also promises to alleviate another problem: if paper has become wet, it has previously been nearly impossible to detect fingerprints because the amino acids in the sweat, which are the primary substrate for current chemical enhancement reactions, are dissolved and washed away by water. The fatty components are barely effected.

About the Author
Joseph Almog is a Professor of forensic chemistry at the Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem, and formerly the director of the Division of Identification and Forensic Science (DIFS) of the Israel Police. His main research topics are development of crime-scene techniques, explosives detection and identification and enhancement of latent fingermarks. He is the 2005 laureate of the American Academy of Forensic Sciences' Lucas Medal "for outstanding achievements.
Author: Joseph Almog, Hebrew University of Jerusalem (Israel), http://www.huji.ac.il/dataj/controller/ihoker/MOP-STAFF_LINK?sno=208470

Title: Visualization of Latent Fingermarks by Using Nanotechnology for Reversed Development on Paper: A Remedy to the Variation in Sweat Composition

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201205259

Joseph Almog | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht Rapid adaptation to a changing environment
28.04.2016 | Christian-Albrechts-Universität zu Kiel

nachricht Tiny microscopes reveal hidden role of nervous system cells
28.04.2016 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

Im Focus: New world record for fullerene-free polymer solar cells

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences (CAS). This work is about avoiding costly and unstable fullerenes.

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences...

Im Focus: Ultra-thin glass is up and coming

As one of the leading R&D partners in the development of surface technologies and organic electronics, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP will be exhibiting its recent achievements in vacuum coating of ultra-thin glass at SVC TechCon 2016 (Booth 846), taking place in Indianapolis / USA from May 9 – 13.

Fraunhofer FEP is an experienced partner for technological developments, known for testing the limits of new materials and for optimization of those materials...

Im Focus: Measuring the heat capacity of condensed light

Liquid water is a very good heat storage medium – anyone with a Thermos bottle knows that. However, as soon as water boils or freezes, its storage capacity drops precipitously. Physicists at the University of Bonn have now observed very similar behavior in a gas of light particles. Their findings can be used, for example, to produce ultra-precise thermometers. The work appears in the prestigious technical journal "Nature Communications".

Water vapor becomes liquid under 100 degrees Celsius – it condenses. Physicists speak of a phase transition. In this process, certain thermodynamic...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

Possible Extragalactic Source of High-Energy Neutrinos

28.04.2016 | Physics and Astronomy

University of Illinois researchers create 1-step graphene patterning method

28.04.2016 | Materials Sciences

Rapid adaptation to a changing environment

28.04.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>