Smart holographic sensors can test for and monitor diseases | Open Mind & Open Heart |



A person would just have to check the hologram's color against a chart or use a camera phone to read the results. As these holographic sensors don't require batteries, electricity or lasers to function, it's possible to create inexpensive portable tests for healthcare workers to use or people to self-administer, that could help them potentially diagnose diseases in their earliest stages.


"We often see holograms on banknotes, credit cards, as security features, or artwork," Ali Yetisen, a PhD student at the University of Cambridge, UK, who led the research, tells Gizmag. "However, these type of holograms do not response when they encounter a health condition indicator such as glucose or blood electrolytes. We have developed techniques to make these holograms 'smart,' so that they can respond to a wide range of disease markers."


The holographic sensors are made out of hydrogels (a highly absorbent material) that are doped with silver nanoparticles. These silver nanoparticles are then organized into three-dimensional holograms of predetermined shapes using a multi-megawatt laser. The final sensors resemble the iridescent hardened forewings of beetles, and normally diffract light in a green color. 


However, when the holographic sensor is exposed to a person's breath, urine, tears or a drop of their blood or saliva, the hydrogel in the sensor, which is sensitive to specific disease indicators, reacts if any of them are present. The hydrogel either swells or shrinks, causing a change in the hologram's color in the entire visible spectrum. It's the first time, the researchers claim, that they've been able to achieve such a result with a colorimetric sensor. 


"It's pretty much like a butterfly wing," says Dr. Haider Butt, a Lecturer in Micro Engineering and Nanotechnology, at the University of Birmingham and a co-author of the study. "But this is a butterfly wing that changes color depending on the solution we dip it in."

Via Jeff Morris, Dr. Stefan Gruenwald