Comparative Study of latent fingerprint impression over different materials like plastic sheets, Mica, Aluminium (Al), Copper (Cu) and their Interpretation in terms of Potential surge instead of old classical theories

Fingerprints over various metals like aluminium (Al), copper (Cu) and various non metals like mica and plastic sheets have been investigated in this work and an approach is being made to interpret the results in terms of potential surge as compared to old classical theory of open pit corrosion on the basis of two major facts. Firstly, we all know that corrosion is a very slow process but fingerprints are formed very frequently in a short interval of time then how come we understand the role of open pit corrosion theory? Secondly, how come we interpret the formation of finger prints over non metals like thin plastic sheets and mica? It is strongly assumed by me (dhir) that this theory is not fully justified for fingerprint impressions over different non metals & metals. Instead of this theory I proposed a new theory based on potential surge (i.e. Energy gap). Moreover, it is being observed by me that the formation of finger prints over thin film of plastic sheets (having fine edges) is more readily and brightly as compared to film having high thickness. Different types of metals & non metals have been investigated in this study and fingerprint over different thin plate of various metals & non metals like aluminium (Al), copper (Cu), thin plastic sheets & mica have been used. Ionic salts present in the fingerprint residue corrode the metal surface of these metals to produce an image of the fingerprint. It is being noted that the imprint of finger print on metals are brighter as compared to on non metals. However the trend appears as follows:

Copper > aluminium > thin plastic transparent sheets > mica > thick transparent sheets

However, I interpret the results on the basis of potential surge (i.e. Energy gap). The magnitude of this potential difference is affected by electrolytes present in solution on the surface of the metal, which, in the case of fingerprints, are ionic salts such as sodium chloride (NaCl) present in the fingerprint residue. Ionic adsorption and redox corrosion reactions at the metal surface produce the observed variations in potential difference across the metal surface. By measuring this variation in potential, an image of the fingerprint was visualized in terms of potential surge.