The idea of a lab-on-a-fiber is similar to a lab-on-a-chip, which already exists. The main problem with using an integrated electronic chip in human health is that we’re very wet and goopy inside. A lab-on-a-chip is made largely of metal semiconductors that corrode under such conditions, but a glass optical cable doesn’t have that problem. These chips are also too large to be implanted in the body, but fiber optics could be threaded directly into the blood vessels for real time monitoring.
Making a photonic cable system capable of analyzing chemical signatures is, in some ways, very similar to making it work in telecommunications. The inner surface of a standard fiber optic cable is coated with tiny amounts of germanium oxide, making it more reflective. When light is sent down the cable, it bounces off the inner surface and remains confined to the core. That’s why fiber optic cables can transmit data so far with little to no signal loss. The most promising approach to building a lab-on-a-fiber relies on this property of optical fibers to control when and how light leaves the core to detect target molecules.