Graphene And Fingerprints

As a forensic chemist, I was fascinated by “Covering Up For A Clear View,” on using graphene to reveal the structure of water on a surface (C&EN, Sept. 6, page 11).

The most common and abundant component of a typical latent fingerprint is water. I realize that the work done by Caltech chemists Ke Xu, Peigen Cao, and James R. Heath was done on a nanoscale. However, I wonder what you would see if you covered a partial latent fingerprint with such a thin graphene blanket?

Historically latent prints have been identified and compared on the basis of ridge detail. “Poroscopy” was a rather esoteric feature with which any experienced latent print examiner would have knowledge but would seldom if ever actually use in the course of a career. In a developed fingerprint that is of exceptionally high quality one can see a pattern of pores within the ridgelines.

Would the “graphene blanket” technique be able to reveal poroscopy patterns that were so detailed that a statistically valid identification could be made? (That is, assuming the corresponding area could be found on the record print and over only a relatively small area, since it is just a “partial” latent.) At least initially, this method would only be of use when you already had a strong suspect or you strongly suspected the victim (perhaps an abducted child) had been in a vehicle or some other location associated with a suspect. (Noble, D. “Vanished into thin air: The search for children’s fingerprints,” Anal. Chem. 1995, 67:435A.)

But wouldn’t it be great if this method could develop identifiable latents deposited by children where other past methods just didn’t produce enough ridge detail? Many potential latent print-bearing surfaces might not be amenable to the graphene blanket process, but if the Caltech chemists used a mica substrate then I should think that a glass pane (for example, the inside surface of a vehicle window) might also work.

Robert D. Blackledge
El Cajon, Calif.