A powder made up of zinc oxide nanoparticles can give crime fighters a clearer image of fingerprints, even on wet surfaces, say Australian researchers.
McDonagh says traditional powder reveals fingerprints by sticking to the oily residues left on the surface - but this doesn't always work.
Elusive fingerprints include those found on wet surfaces such as sinks or bath tubs, especially when part of the print has been washed away.
Working with the Australian Federal Police, McDonagh and team tested a new fingerprint powder based on zinc oxide nanoparticles on surfaces such as glass, polyethylene and aluminium.
He says the 20-nanometre zinc oxide particles clump together in 1 micrometre sized flower-like crystals - much smaller than the current 10 micrometre fingerprint powder particles.
When illuminated with ultraviolet light the nanoparticles fluoresce without the addition of any fluorescent dyes.
Compared to conventional powders the researchers found the zinc oxide nanoparticle powder gave a much clearer picture of the fingerprints.
"When you dust with a powder, you're hoping that it will stick only to the fingerprint, but often it will stick to everything," says McDonagh.
"[The nanoparticles are] very good at sticking to the fingerprint residue but not to the background surface."
The researchers also found the system worked exceptionally well in wet conditions.
When they immersed the material with fingerprints into a solution of the nanoparticles, it delivered very clear prints.