Press-And-Go Fingerprinting

By spinning nanosized fibers from a polyurethane resin and the dye fluorescein, chemists have developed a portable mat that can quickly detect latent fingerprints on surfaces such as glass, wood, or marble (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201006537). The mats don’t require pre- or posttreatments, lift prints nondestructively, and display prints in 30 seconds after exposure to hot air. Shengyang Yang, Cai-Feng Wang, and Su Chen from China’s Nanjing University of Technology applied an electrospinning technique to solutions of commercial thermoplastic polyurethane resin and fluorescein to obtain the mats. The team suggests that chemical components of sweat in fingerprint residues react with trace isocyanate groups in the polyurethane to produce cross-links, releasing fluorescein from the nanofibers to produce images. A given spot on a mat is not reusable, but the mats, which measure about 12 × 50 cm, can be divided for multiple uses, Chen says. In the absence of fingerprints, the mats have proven stable for six months so far, Chen notes, so they could be useful for forensics or medical diagnostics.