Three-Dimensional Conductive Fingerprint Phantoms Made of Ethylene-Vinyl Acetate/Graphene Nanocomposite for Evaluating Smartphone Scanners

Fingerprints consist of unique patterns of skin ridges and valleys, and are commonly described by three levels of feature details. Most fingerprint identification systems rely on matching only first- and second-level details; their calibration using unrealistic targets combined with human sampling are cumbersome and time-consuming. We have developed a true-to-life fingerprint phantom with optimized conductive properties and third-level fingerprint details for developing more reliable matching algorithms for popular capacitive fingerprint scanners. An impression of a live finger is made into a solvent-softened polycarbonate template, which is subsequently adapted to thermally mold ethylene-vinyl acetategraphene (EVA-G) nanocomposite of satisfactory conductivity (1.2 ± 0.1 × 10–3 S/m) and mechanical flexibility. It was confirmed with SEM, optical, and profilometry imaging that the phantom made of EVA-G nanocomposite replicates the three-dimensional morphology of fingerprint with high fidelity, including well-defined third-level details. The EVA-G phantoms can operate capacitive scanners in popular brands of smartphones and tablets with either iOS or Android operating systems (>80% success rate). As these permanent phantoms include defined third-level details based on real fingerprints, their potential application as calibration standards for developing the next generation of scanners with improved security is warranted.