This pressure-responsive polymer collapses when a small force is applied to it and quickly returns to its original shape when no longer compressed. The technology is useful for identity authentication systems. The Federal Bureau of Investigation (FBI) alone maintains the fingerprints of more than 100 million American citizens and new entries are added every day. Stored fingerprint images and fingerprint readers allow law enforcement officers and others to track individuals' security clearances and criminal activity. Proper fingerprint image acquisition is critical for later authentication.
Researchers at the University of Florida have developed a polymer that memorizes the shape of 3D objects, such as fingers' friction ridges (unique raised patterns of the epidermis). While in its collapsed state, the polymer is transparent. It changes color in response to pressure, providing visual proof that a high-quality fingerprint has been acquired. The technology can be adapted for other optical applications, such as anti-glare and anti-counterfeiting coatings.
A pressure-responsive polymer for improved fingerprint acquisition and recognition, which changes color when compressed
University of Florida researchers have developed a pressure-responsive polymer that changes color when compressed and memorizes the shape of any 3D object. The polymer is comprised of hydrogel-like macroporous membranes with highly ordered pores. The pores collapse under pressure and immediately recover when pressure is alleviated. In its compressed state, the polymer is transparent due to the collapsing of the pores. In the locations of pressure, the film recovers its 3D structure and becomes iridescent. It shows a rainbow of colors at the points of pressure due to the Bragg diffraction of visible light from the 3D ordered crystalline structure.
