Fibre optic sensors that dissolve in the body could open door to new treatments

Researchers have created fibre-optic sensors designed to dissolve in the body after use. They could be used for monitoring the healing of bone fractures, or safely exploring sensitive organs such as the brain.

The sensors, made by a Greek and Italian research team, are a form of Bragg grating (pictured), which work by turning an optical fibre into a sensing element by reflecting a specific wavelength back in the direction it came.

They are usually used for real-time monitoring on large structures such as bridges or airplane wings, but thanks to this new development they could now be used inside the body too. “Our work paves the way toward optical fibre sensors that can be safely inserted into the human body,” said Maria Konstantaki, one of the researchers from the Institute of Electronic Structure and Laser at the Foundation of Research and Technology-Hellas in Greece. “Because they dissolve, these sensors don’t need to be removed after use and would enable new ways to perform efficient treatments and diagnoses in the body.”

Working with scientists from the Politecnico di Torino and Istituto Superiore Mario Boella in Italy, they created a special type of glass that could be safely used in the body. It is made of phosphorous oxide, combined with oxides of calclum, magnesium, sodium and silicon.  "This glass combines excellent optical properties with biocompatibility and water solubility, thus providing a reliable platform from which to make optical fibers that dissolve in water or biological fluids," said Daniel Milanese from Politecnico di Torino. "The properties of the optical fibers can be tuned by properly changing the glass composition."

They then demonstrated that they could etch working Bragg gratings onto the fibres, and immersed them in fluid that simulated the pH and temperature of the human body.

The fibres could be used to sense pressure at joints, or tiny probes for the heart and other organs. They could also be used to deliver and measure laser treatment for removing tumours. "This is the first time that a widely used and well-calibrated optical element such as a Bragg grating has been etched into a bioresorbable optical fiber," said Konstantaki.

"Our approach could potentially be used to create various types of interconnected structures in or on bioresorbable optical fibers, allowing a wide range of sensing and biochemical analysis techniques to be performed inside the body."