Atomic Force Microscopes (AFM) have tips that are of nanometric scale (a nanometer is one-billionth of a meter). By measuring and analyzing the deflection of the lever to which the tip is attached, information about the invisibly small measured object can be computed.
The scientific support unit of Northamptonshire Police, UK, has now found a way to lift fingerprints from bullets and other metal objects using AFMs. Fingerprint recovery from bullets is currently very low and even a small increase in the success rate is considered significant for forensics.
Earlier, fingerprints were being lifted by applying powder to the material, a method that can damage the evidence. Scientists at the police support unit now employs natural heat and humidity to let the fingerprint image be enhanced and uses AFM and other tools to recover the image.
When a finger touches a metal surface, it leaves a residue that interacts with the metal. Using temperature and humidity, the interaction results can be converted into a permanent image. Components of the sweat deposit can even survive washing and wiping.
Read the story at: Fingerprint Detection with Nano Device
