Fingerprints move over time

What is it about?

Fingerprints deposited on surfaces are a complex mixture of water, fats and salts. Our work shows that over a period of up to 2 months as thin layer of material, about 4nm , 4 millionths of a millimetre, thick moves across the surface, migrating away from the original print. Initially visualised on silicon, using this atomically smooth surface enables us to visualise the phenomenon, we have adapted the technique to allow us to study more forensically relevant surfaces such as Formica, where instead of imaging the height as shown here we study the physical stiffness of the surface. This work has been partially funded by the Home Office.

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Why is it important?

Movement and distribution of components of the fingerprint over a surface has implications in the development of the fingerprint, for example with vacuum metal deposition or nanostructured powders. Knowledge of these processes will help ensure choice of the best technique for fingerprint development and help future research into mark visualisation, for example on polymer banknotes. There is potential for further exploration to help with determining the age of the fingerprint.