Collection of rolling fingerprints by the electrochromism of Prussian blue

Abstract

The collection of rolling fingerprints with the electrochromismic method was presented with electrochemically deposited Prussian blue film on an ITO plate. The morphology of the film was characterized by optical microscopy, scanning electron microscopy and electrochemical method. It was found that the obtained film is compact and uniform with a thickness of ca. 500 nm. The electrochromism of the film was explored for fingerprint collection. The influences of the applied potentials and the humidity on the electrochromism were investigated. When the applied potentials were controlled in the range of 25–40 V and the humidity of the environment was in the range of 65–80%, clear fingerprints can be obtained by rolling the bare finger on the Prussian film. The second-level details, such as the ridge lakes, termination, crossover and bifurcation can also be clearly observed. This fingerprint collection method is simple, rapid, and non-invasive, and the collected fingerprints could be readily electronized for the establishment of a fingerprint library.