Why your phone might one day tell you that you're pregnant

Fiber-optic sensor could enable smartphone pregnancy tests

German researchers have hacked together a fiber-optic sensor that uses a smartphone's flash and camera to perform a variety of biomolecular tests, including pregnancy diagnosis.

It works using a phenomenon called 'surface plasmon resonance', which is when light jiggles around the electrons on the surface of a thin metallic film in contact with a fluid. From the way the electrons jiggle, it's possible to work out the composition of that fluid, or the presence of particular molecules or gases.

Normally the process needs bulky lab equipment, but the team from the Hanover Centre for Optical Technologies managed to slim it down to something that'd fit on the rear side of a smartphone.

The flash provides the light through a fiber-optic cable, and the reflection is then carried to the camera through a diffraction grating that splits it into its component colours. From the way the brightness of the colours differs, it's possible to tell what's in the liquid.


Tests showed that the device's sensitivity is comparable to the aforementioned bulky lab equipment, despite the tiny device coming in at a fraction of the cost.

As well as letting researchers perform more complex analysis in the field, it could eventually allow smartphone owners to diagnose pregnancy or monitor diabetes - though we're still some way away from that point.

"We have the potential to develop small and robust lab-on-a-chip devices for smartphones," said Kort Bremer, who invented the technique. "So, surface plasmon resonance sensors could become ubiquitous now."

The device was detailed in a paper in Optics Express.

Duncan Geere
Duncan Geere is TechRadar's science writer. Every day he finds the most interesting science news and explains why you should care. You can read more of his stories here, and you can find him on Twitter under the handle @duncangeere.