disclosed is a double - sided grating waveguide biosensor . the double - sided grating waveguide biosensor is used to sense the properties of a sample solution . the double - sided grating waveguide biosensor comprises a sequential stack of a plastic grating having a grating part , a waveguide layer having a double - sided grating structure , and a channel chip . furthermore , the sample solution is guided into the channel chip ; the light beam is coupled into the waveguide layer via the double - sided grating structure , propagates in the waveguide layer , and penetrates outward . the double - sided waveguide biosensor detects the properties of the sample solution via a variation of a light beam intensity of the outgoing light beam .