Electrochromic fluorescent film can make fingerprints higher-res, help solve crime

You’re likely quite familiar with the standard method of dusting for fingerprints portrayed in so many movies and TV shows, but that method doesn’t pick up every potential fingerprint. Using fluorescent films that change color, researchers have figured out a better way to reveal fingerprints that might have otherwise gone undiscovered or been unidentifiable.
Though you may love Law & Order and all of its permutations, Dick Wolf may have steered you wrong. When using the standard method of dumping powder on leftover finger sweat and grease, only about 10% of those fingerprints found at crime scenes are able to be used in court. This is because the sweat-and-grease leftovers are susceptible to a wide variety of outside forces, such as surrounding environmental effects, as well as someone attempting to wipe down the area with simple cleaning solutions. However, thanks to a joint effort by researchers at the University of Leicester, STFC, and the Institut Laue-Langevin, a quick wipe from a hanky won’t necessarily remove fingerprints from, for example, the grip of a gun.

The Leicester researchers developed a method of fingerprint detection that, rather than hoping powder sticks to human residue, sticks to the residue thanks to its naturally electrically insulating properties. By using a film that employs electrochromic polymers, the researchers can exploit those insulating properties by applying an electrical charge. This causes the film to highlight the areas in between the finger residue, which provides accurate fingerprint data for the same reason why we can easily recognize an illustration made using negative space instead of standard outlines. Unfortunately, this technique by itself requires the human residue to be left extremely intact, and can be easily foiled by any disruption of the residue. However, this method can be bolstered thanks to the addition of fluorophore, which is a compound that can emit light if excited.
When the new fluorescent film is applied to a fingerprint, the quality of the print may not be up to electrochromic par, but the team can invoke the light from the fluorophore compound, creating a clearer picture of the print. Using this new combination of methods, the resolution of fingerprints can be adjusted to the best possible clarity and level of detail — perhaps like focusing the lens of a camera, but with chemicals and electricity.
In the testing lab, the team was able to better identify fingerprints using the method, but they admittedly haven’t tried the method out in the real world just yet, where fingerprints are exposed to a host of potentially deleterious forces. However, if they can adjust the resolution on somewhat deteriorated fingerprints, it could prove to be a much more useful tool than the standard method, since powder is just powder and can’t be zoomed or enhanced.