AsianScientist (May. 2, 2014) – Scientists have engineered a water-sensitive material that can be used to create high-precision maps of the sweat pores on fingertips. Compatible with existing inkjet technology, the material known as hydrochromic polydiacetylene (PDA) is colorless when first printed, blue upon UV treatment and turns red upon contact with water.
Current fingerprinting methods rely on the detection of unique ridge patterns of an individual’s fingertips. However, when you touch an absorbent material such as paper, what gets left behind is the pattern of sweat pores rather than the complete ridge patterns themselves. High resolution imaging of the sweat pores requires complicated software, and is unable to distinguish active sweat-secreting pores from those that are not functioning.
To get around this problem, a team of scientists led by Dr. Kim Jong-Man from Hanyang University has come up with a polymer that changes color upon contact with water. When dry, hydrochromic PDA exhibits a layered structure. The absorption of water twists the layers apart, causing the material to absorb longer wavelengths of light and appear red.
Hydrochromic PDA is sensitive enough to detect the sub-nanoliter amounts of water in fingertip sweat pores, changing instantly from blue to red and also emitting red fluorescence. The fluorescent images from hydrochromic PDA films reliably matched latent fingerprints. Furthermore, the technique is able to make matches based on smaller or fragmentary prints and can be used to distinguish between functioning and non-functioning pores.
Apart from applications in fingerprint identification, the technology might also be useful in the diagnosis of sweat-pore disorders.
The article can be found at: Lee et al. (2014) Hydrochromic Conjugated Polymers for Human Sweat Pore Mapping.
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Copyright: Asian Scientist Magazine; Photo: Nature Publishing Group.
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