Electrochromic enhancement of latent fingerprints on stainless steel surfaces

The visualization of latent fingerprints on a metallic (stainless steel) surface is described by means of spatially selective deposition of an electrochromic polymer (polyaniline). Inhibition of electrochemical processes on areas of the surface masked by the fingerprint results in polymer deposition generating a negative image of the fingermark. By variation of the applied potential, the polymer optical characteristics can be continuously and reversibly adjusted to optimize visual contrast of the fingerprint.