Fingerprints can be latent (invisible), patent (visible), or plastic (impressions in materials). Latent prints contain residue from sweat and skin oils and can be developed chemically or physically. Ninhydrin and diazafluorenone react with amino acids in fingerprints. New methods like vacuum metal deposition and laser fluorescence allow fingerprints to be developed without destroying their chemical composition, allowing for DNA analysis. Researchers at Penn State have developed a new conformal evaporation technique using gold and chalcogenide glass to amplify fingerprint ridges for analysis while preserving DNA.

1. Outline: Current Event on Fingerprinting
Chris Strein
A fingerprint is an __________________ of the friction ridges of all or any part of the
finger.
• Types of fingerprints:
• Latent
• __________________
• Plastic
Latent:
• A fingerprint is any chance of accidental impression left by friction ridge skin on
a surface, regardless of whether it is visible or invisible at the time of
___________________
• Electronic, chemical and physical processing techniques permit visualization of
invisible latent print residue whether they are from natural secretions of the
_____________________ glands present on friction ridge skin (which produce
palmar sweat, consisting primarily of water with various salts and organic
compounds in solution), or whether the impression is in a contaminant such as
motor oil, blood, paint, ink, etc.
Patent:
• These are friction ridge impressions of unknown origins which are obvious to the
human eye and are caused by a transfer of ____________________ material on
the finger, onto a surface
Plastic:
• A plastic print is a friction ridge impression from a finger or palm (or toe/foot)
deposited in a material that retains the shape of the ridge detail
Methods of Detection:
• Ninhydrin and Diazafluorenone
• Vacuum Metal Deposition
• Ethyl Cyanoacrylate Polymerisation
• _____________________
• Argon Ion Lasers
Ninhydrin:
• Fingerprint reagents that are specific, for example Ninhydrin or Diazafluorenone
react only with amino acids to show the fingerprint
Various Methods:
• _________________ cyanoacrylate polymerisation, work apparently by water
based catalysis and polymer growth
• Vacuum metal deposition using gold and zinc has been shown to be non-specific
but detect fat layers as thin as one molecule
Adhesives:
• More mundane methods such as application of fine powders work by adhesion to
___________________ deposits and possibly aqueous deposits for fresh
fingerprints that outline the print

2. • Argon Ion lasers use a wide range of fluorescence techniques primarily for the
enhancement of chemically developed fingerprints but also for some detection of
inherent fluorescence of the ________________ fingerprints
DNA vs. Development:
• Fingerprint Development like the traditional methods just explained have a
downside though. In fact, the chemical methods have multiple downsides. The
chemistry of the fingerprint is destroyed or altered during the process of
development and forensics have issues in obtaining the DNA of the fingerprint.
Also, the methods rely on specific substances and sometimes are not effective
based on the traces left.
The New Method:
• The method was developed at Penn State University and is being patented by
professors Robert ___________________ and Ahklesh Lakhtakia via provisional
patent application for the process
• “The process is called conformal-evaporated-film-by-rotation, and was originally
developed to create highly-detailed copies of biological surfaces such as insect
eyes or butterfly wings. It utilizes a form of physical vapor deposition where
materials are heated in a vacuum, causing them to vaporize and then condense on
the surface of an object rotating above them, covering that object in a thin film.”
• “In the case of Penn State’s technique, the materials that they heated were
_______________ ___________________ and chalcogenide glass, which is a
combination of germanium, antimony and selenium. The film created was only
about one micron thick, but that was enough to essentially “amplify” the ridges
and valleys of fingerprints, allowing analysts to read them with an optical device.”