Smartphone Pregnancy Test

A self-contained fiber-optic sensor for smartphones has been developed that could enable users to conduct a wide variety of biomolecular tests, including pregnancy testing or diabetes monitoring. It uses the principle of surface plasmon resonance (SPR) to detect the presence of biomolecules and/or trace gases in basically the same way that a bulky laboratory analyzer functions. However, the new device is a small and robust lab-on-a-chip that is attached to a smartphone and can be designed to monitor a variety of body fluids or gases, such as blood, urine, saliva, sweat and exhaled air.

The u-shaped device is comprised of an optical fiber with a diameter of about 400-micrometers, the ends of which are polished to a 45-degree angle. A portion of the glass fiber is coated with silver, and a small well holds the solution to be analyzed. When attached to the phone case, light from the phone’s LED passes through the sample and is separated into an emission spectrum by means of a diffraction grating. The camera records the spectrum and an onboard app analyzes it to provide real-time results.

In experiments using varying concentrations of glycerol, the sensitivity of the new device was demonstrated to be comparable to current laboratory equipment. In addition to being only a fraction of the size and cost, the ability to provide direct feedback could be lifesaving. For example, if sensor readings indicate a possible emergency, the app could be programmed to automatically interrogate the smartphone’s GPS locator, guide the user to a nearby hospital or drug store, or even send for an ambulance.