Researchers from the University of Cambridge, UK, are working to develop portable medical tests and devices, which could be used to monitor conditions such as diabetes, cardiac function, infections, electrolyte or hormone imbalance easily and inexpensively using color-changing holograms that react in the presence of certain compounds.

The “smart” holograms can be used to test a variety of bodily fluids, including blood, urine, saliva, or tears for a wide range of compounds, such as glucose, alcohol, hormones, drugs, or 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 chart.

The project uses hydrogels impregnated with tiny particles of silver. Using a single laser pulse, the silver nanoparticles are formed into three-dimensional holograms of predetermined shapes.

When 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 any hydrogel-based sensor, they say. A major advantage of the technology is that the holograms can be constructed in a fraction of a second, making the technology highly suitable for mass production.

Clinical trials of the holographic sensors to monitor glucose levels and urinary tract infections in diabetic patients are currently underway at Addenbrooke's Hospital, part of Cambridge University Hospitals.

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