A flexible optic fiber sensor film, a mat structure comprising the same and a method of use of the mat structure are provided. The flexible optic fiber sensor film comprises a sandwiched layer and an optic fiber cable arranged in the sandwiched layer the flexible optic fiber sensor film further comprises protrusions arranged on the sandwiched layer to abut against the optic fiber cable. The flexible optic fiber sensor film is configured for generating light loss in the optic fiber cable when there are body movements of a human subject lying on top of the flexible optic fiber sensor film. The application is safe and comfortable to the human subject.