Berlin: Small add-on devices could allow your smartphone to take pregnancy tests or monitor diabetes, scientists say. Researchers at the Hanover Centre for Optical Technologies (HOT), University of Hanover, Germany, have developed a self-contained fibre optic sensor for smartphones with the potential for use in a wide variety of biomolecular tests, including those for detecting pregnancy or monitoring diabetes.
According to the researchers, the readings of the sensor can run through an application on a smartphone which provide real-time results. When properly provisioned, the smartphone user has the ability to monitor multiple types of body fluids, including blood, urine, saliva, sweat or breath.
In case of medical applications, the sensor readings can be combined with the GPS signal of a smartphone and users can then be guided to the next drug store, hospital or the ambulance, the researchers said. The sensor uses the optical phenomenon of surface plasmon resonance (SPR) - which occurs when light causes electrons on the surface of a thin film to jostle - to detect the composition of a liquid or the presence of particular biomolecules or trace gases.
"We have the potential to develop small and robust lab-on-a-chip devices for smartphones. So, surface plasmon resonance sensors could become ubiquitous now," said Kort Bremer, co-author of the new study with Bernhard Roth, director, Hanover Centre for Optical Technologies (HOT), University of Hanover.
Surface plasmon resonance is a phenomenon commonly used for biosensing, but typically requires bulky lab equipment involving both a light detector and light source. Smartphones already have both of these, allowing the minimalist, U-shaped device the researchers designed to consist solely of a 400-micrometre diameter core multimode fibre with a silver-coated sensing region.
In a proof-of-concept version of the sensor, Bremer carefully excised the polymer coating from a 10 millimetre segment of the optics cable to expose the bare 400 micrometre diameter glass fibre core. He then cleaned the segment, subjected it to a silver-coating process, added a small well in which to pour the solutions being observed, and polished both ends of the fibre to 45 degree angled faces.
They were then adhered to the phone's case and, thus, to its LED and camera, the latter of which was affixed with a diffraction grating to separate the light beam into an emission spectrum. In subsequent experiments, the device's sensitivity was tested using various concentrations of glycerol, and the team confirmed it was on par with current equipment, at a fraction of the cost and size. The study was published in Optics Express, a journal of The Optical Society.
