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According to a report in the journal Advanced Optical Materials, “smart” holograms are currently being tested to monitor diabetes and could be used to monitor a range of medical and environmental conditions in the future.
The responsive holograms, which change color in the presence of certain compounds, are being developed by investigators in the U.K. The goal of the new research is to eventually use the holograms in portable medical tests and devices to monitor diabetes, cardiac function, infections, electrolyte or hormone imbalance, and other conditions.
The holograms test blood, breath, urine, saliva, or tear fluid for a range of compounds, including glucose, alcohol, hormones, drugs, and bacteria. When one of these compounds is present, the hologram changes color, potentially making the monitoring of various conditions as simple as checking the color of the hologram against a color gradient.
Clinical trials of the holographic sensors to monitor glucose levels and urinary tract infections in diabetic patients are currently under way at Cambridge University Hospitals.
The investigators are using a highly absorbent hydrogel, similar to contact lenses, impregnated with tiny particles of silver. When exposed to a single laser pulse, the silver nanoparticles form into three-dimensional holograms of predetermined shapes in a fraction of a second.
In the presence of certain compounds, the hydrogels either shrink or swell, causing the color of the hologram to change to any other color in the entire visible spectrum — the first time that this has been achieved in a hydrogel-based sensor, the investigators say.
Source: University of Cambridge; January 22, 2014.