Three-Dimensional Conductive Fingerprint Phantoms Made of Ethylene-Vinyl Acetate/Graphene Nanocomposite for Evaluating Smartphone Scanners
Clayton W. Schultz, Mirette Fawzy, Farzad Nasirpouri, Karen L Kavanagh, Hua‐Zhong Yu · ACS Applied Electronic Materials · 2021
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.