The electrochromic detection of latent fingermarks on polished or unpolished, flat or curved metal surfaces is described using electrochromic material, 1,1’-dibenzyl-4,4’-bipyridinium dichloride. The surface area covered by fingermarks acts as an insulating mask, causing 1,1’-dibenzyl-4,4’-bipyridinium dichloride to change color and produce inversed images of the fingermark. By changing the applied potential, the optical properties of 1,1’-dibenzyl-4,4’-bipyridinium dichloride can be continuously and reversibly adjusted to optimize the visual contrast of fingermarks, so as to realize the detection of latent fingermarks on stainless steel surface. It is demonstrated that the fabricated electrochromic devices can detect the fingermarks on these types of surfaces within twenty seconds at −1.0∼−2.0 V. This work can qualify as a tangible improvement in fingermark detection of the natural fingermarks on the never-cleaned (more than 3 years) and curved surfaces of daily-used container, e. g. cup, and the handle of cleaning tool, mop.

中文翻译：

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使用 1,1'-二苄基-4,4'-联吡啶二氯化物对金属表面潜在指印进行电致变色检测

使用电致变色材料 1,1'-dibenzyl-4,4'-bipyridinium dichloride 描述了抛光或未抛光、平坦或弯曲金属表面上潜在指印的电致变色检测。指纹覆盖的表面区域充当绝缘掩模，导致 1,1'-dibenzyl-4,4'-bipyridinium dichloride 改变颜色并产生指纹的反转图像。通过改变外加电位，可连续可逆地调节1,1'-二苄基-4,4'-二氯化联吡啶的光学性质，优化指印的视觉对比度，从而实现对不锈钢潜在指印的检测表面。结果表明，制造的电致变色器件可以在 -1.0∼-2.0 V 的 20 秒内检测到这些类型表面上的指纹。这项工作可以说是对从未清洁过（超过 3 年）和日常使用容器的弯曲表面上的自然指纹检测的明显改进，例如。G。杯子，以及清洁工具，拖把的手柄。