Due to the uniqueness of each fingerprint, latent fingerprints are often used as proof that a person was present at a scene. Latent fingerprints are not normally visible in daylight, so several methods have been developed to enable their visualization. These can take over 15 min per fingerprint.

Su Chen and co-workers, Nanjing University of Technology, China, have developed a method that uses a commercial resin that allows ultrafast identification of latent fingerprints. They use an electrospun thermoplastic polyurethane/fluorescein nanofiber mat which could be pressed against various surfaces containing fingerprints. The fingerprints could then be visualized after exposing the mat to hot air (100 °C).

This technique is unique in that latent fingerprints can be non-destructively lifted from surfaces and developed within 30 s in daylight without the need for laborious pre-/post-treatment processes.

• A Release-Induced Response for the Rapid Recognition of Latent Fingerprints and Formation of Inkjet-Printed Patterns
  S. Yang, C.-F. Wang, S. Chen,
  Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201006537
• News: See Hidden Fingerprints
  Fingerprints that have been washed off metal surfaces can now be retrieved