The idea is that readings from the sensor could use a smartphone app to give results and the scientists suggest that combined with GPS an app could tell a patient to the way to a hospital or a doctor.
Writing in Optics Express, the scients said that the sensor uses surface plasmon resonance (SPR) to detect what’s in a liquid.
SPR happens when light strikes a metallic film and while most of the light gets reflected, a small band is picked up by surface electrons, making them resonate. By adding recognition elements to the film, an app can use a biological sample to detect its composition.
SPR devices usually need bulky lab equipment using a light detector and light source but a smartphone already has both.
The prototype the scientists made (pictured) uses a 400 micrometre diameter core multimode fibre with a silver coated sensing region.