Flexible thermosensitive films based on shallow-trap persistent luminescence for high-resolution texture imaging of fingerprints even through latex gloves

Abstract

Here, we have developed a novel thermosensitive technique based on shallow-trap persistent luminescence to achieve high-resolution and long-duration texture imaging of fingerprints even through latex gloves. A thermosensitive flexible film that consists of a transparent silica gel embedded with a shallow-trap Bi₂Ga₄O₉:Eu³⁺,Cr³⁺ (BGO) phosphor microarray exhibits broadband near-infrared PersL, which enables sensitive temperature sensing using a thermally stimulated luminescence (TSL) method. The uniform surface conical arrays of the BGO film ensure a high thermal sensing resolution. Only a simple touch is enough to induce thermal distribution that can be easily visualized as luminescence using an EMCCD camera. Furthermore, the BGO film responds rapidly to small temperature fluctuations with high sensitivity (8.10 ± 0.476% K⁻¹), enabling fingerprint imaging even through latex gloves in only a few seconds. This imaging strategy is very promising for sensitive temperature sensing without power supply, and it also opens new application opportunities for shallow-trap PersL materials.