A fiber-optic biosensor is a type of sensor that uses light-based technology to detect and measure biological molecules or processes. This is done by transmitting light along a fiber-optic cable and measuring the light that is reflected back, which is then analyzed to determine the presence or absence of biological molecules. Fiber-optic biosensors are highly sensitive, versatile, and capable of detecting a wide range of biological molecules, making them an important tool in medical diagnostics, drug development, and food safety.