Finger mark identification, which is one of the biological recognition methods, has a history of more than 100 years. In this study, polyvinyl alcohol (PVA)/ninhydrin blend nanomembranes were prepared using needleless electrospinning and applied in latent finger mark detection. The morphology and structure of the PVA/ninhydrin nanomembranes were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results showed that the preferable composition for the best spinnability of the complex solution was 86.9 g/L PVA and 76.1 g/L ninhydrin, using water as solvent. The ninhydrin was uniformly dispersed in the PVA/ninhydrin nanomembranes in the amorphous regions. There was a small amount of hydrogen bonds between the PVA and ninhydrin. The addition of ninhydrin did not affect the crystal structure of PVA. When subjected to hot steam of a weak acidic water bath (pH = 6), the PVA/ninhydrin nanomembranes completely displayed the latent invisible finger marks left on glass or ceramic surfaces in purple within 3–5 min of the steam exposure, which were easily observed by the naked eyes. The purple finger marks on the nanomembranes were due to the reaction of ninhydrin with amino acids in sweat released from the fingers. Both chemical cross-linking and physical adhesion of the membrane to the surface occurred in the area of the finger mark regions. Physical adhesion also developed in the regions without finger marks. Therefore, finger marks identification using electrospun PVA/ninhydrin nanomembranes is simple, rapid, harmless, and sensitive, and does not need large instruments or any type of liquid chemical reagent.

指纹识别是一种生物识别方法，已有100多年的历史。在这项研究中，聚乙烯醇（PVA）/茚三酮共混纳米膜是使用无针静电纺丝技术制备的，并用于潜在的指印检测。使用扫描电子显微镜，傅立叶变换红外光谱和X射线衍射研究了PVA /茚三酮纳米膜的形貌和结构。结果表明，以水为溶剂，使复合溶液具有最佳可纺性的优选组成为86.9 g / L PVA和76.1 g / L茚三酮。茚三酮均匀地分散在非晶区的PVA /茚三酮纳米膜中。PVA和茚三酮之间存在少量氢键。茚三酮的添加不影响PVA的晶体结构。当暴露于弱酸性水浴（pH = 6）的热蒸汽中时，PVA /茚三酮纳米膜在暴露于蒸汽中的3–5分钟内完全显示出残留在玻璃或陶瓷表面上的潜在的不可见指纹，呈紫色。肉眼观察。纳米膜上的紫色指印是由于茚三酮与手指释放的汗液中的氨基酸反应所致。膜与表面的化学交联和物理粘附都发生在指印区域。在没有手指印痕的区域也出现了物理粘附。因此，使用电纺PVA /茚三酮纳米膜进行指纹识别非常简单，快速，无害且灵敏，