Professors of Chemistry at Purdue University have discovered a fingerprint test that can identify what you’ve been touching, whether it be your pet, food, illicit substances, or explosives.  One can get fingerprinted and figure out what they’ve touched which has medical and criminal applications.

The test involves spraying electrically charged liquid onto a small portion of the fingerprint.  Droplets would form on the fingerprint and discharge certain chemical compounds into an analyzer.  The liquid would then be evaporated via heat, and the electrical charge is shifted to the fingerprint molecules.  We can then identify these electrically charged fingerprint molecules using a mass spectrometer.  To get a two-dimensional image of the entire fingerprint, we simply need to repeat the process for the rest of the print.

This test is called Desi, which stands for Desportion Electrospray Ionization.

One advantage that this technique has over others is that it does not only detect the presence of certain substances, but it can literally capture the pattern of the substance in the shape of the fingerprint.  For example, as part of Desi trials, the professors at Purdue experimented with the cocaine-stained fingerprints of volunteers who have touched glass, paper, and plastic.  When the professors applied Desi to the fingerprints on the glass/paper/plastic, they captured cocaine in the exact shape of the fingerprint, thus making certain that the presence of the fingerprint and the cocaine is no accidental matter.

Unfortunately, due to the expensive equipment required for Desi, this method is available only for the largest crime laboratories.