Label-free biosensing method based on refractive index modulation time response

The invention discloses a label-free biosensing method based on a refractive index modulation time response, and belongs to the technical field of label-free biosensors. According to the method, functional magnetic nanoparticles in biomolecule induced magnetic fluid to be detected are self-assembled, a magnetic nanoparticle cluster with a large volume is generated, and the refractive index modulation time response of the magnetic fluid is changed when the modulation magnetic field is applied or removed. Under the action of the same modulation magnetic field, the biomolecules with different concentrations enable the magnetic fluid to generate different refractive index modulation time responses. The refractive index sensor is used for measuring a refractive index modulation time response process of the self-assembled magnetic fluid under the action of an external magnetic field, so that the detection of biomolecules can be realized. The refractive index sensor does not need to be functionalized, the detection