Holograms cost only fractions of a cent, and the technology could usher in an era of "smart labels" that show when food is spoiled or when body glucose and alcohol levels are too high, said Chris Lowe, a professor at Cambridge University, who has started a company, Smart Holograms, based on his technology. Lowe described his work Friday here at a conference sponsored by the American Association for the Advancement of Science.
Prototypes have already been made for contact lenses that monitor glucose levels, thin badges that detect alcohol levels, and sticks that can tell, instantly, if milk has spoiled or become contaminated. The technology promises to be quicker and cheaper than tests used today. It will also require less training, because the hologram itself can be designed to show results graphically.
A test showing that fuel has been contaminated with trace amounts of water reads "dry" or "wet." In a breath alcohol test intended for police offices, suspects breathe onto tiny cards that either show a green automobile or a red X, establishing whether a person is sober enough to drive.
One advantage of the technology is that each hologram costs only a fraction of a cent to produce. Another is the wide applicability. The holograms can detect pH to four decimal places and chemical concentrations of hormones and other biologically important substances. The samples tested do not need to be pure: The holograms can work in milk or even in stool samples from newborns, said Lowe.
The image that appears on the hologram is caused by silver particles on a "smart polymer," a lightweight material similar to everyday plastic. These polymers can be designed to change shape in different chemical environments. This shape change moves bands of silver particles, and patterns of silver particles control the brightness and color of the hologram. Thus, the hologram can be used to display a message, a numerical scale or other readout.