Responsive holograms monitor diabetes
Responsive holograms that change colour in the presence of certain compounds are being developed into portable medical devices for monitoring conditions such as diabetes, cardiac function or hormone imbalance.
The researchers at the University of Cambridge are also developing a prototype smartphone-based test suitable for both clinical and home testing of diabetes.
The technique uses an absorbent material known as a hydrogel, which is similar to that used in contact lenses and impregnated with tiny particles of silver.
Illuminated by a laser pulse, the silver nanoparticles are formed into three-dimensional holograms of predetermined shapes in a fraction of a second. When in the presence of certain compounds, the hydrogels either shrink or swell, causing the colour of the hologram to change to any other colour in the entire visible spectrum.
As a result the holograms can be used to test blood, breath, urine, saliva or tear fluid for a wide range of compounds, such as glucose, alcohol, hormones, drugs, or bacteria.
When one of these compounds is present, the hologram changes colour, potentially making the monitoring of various conditions as simple as checking the colour of the hologram against a colour gradient.
The significance of this technique for medical monitors is the speed with which the holograms can be constructed. 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.
“Currently, a lot of medical testing is performed on large, expensive equipment,” said Ali Yetisen, a PhD student in the Department of Chemical Engineering & Biotechnology, who led the research. “While these sorts of inexpensive, portable tests aren’t meant to replace a doctor, holograms could enable people to easily monitor their own health, and could be useful for early diagnosis, which is critical for so many conditions.”
The team at Cambridge estimates that a single sensor would cost just ten pence to make.