The invention discloses a
cascade seven-
core optical fiber sensor applied to
folic acid detection and a preparation method of the
cascade seven-
core optical fiber sensor, and belongs to the technical field of
optical fiber sensing and biological analysis detection. The sensor comprises a first single-mode
optical fiber, a seven-
core optical fiber section and a second single-mode
optical fiber, a double-
microsphere-cavity structure is arranged at the optical
fiber connecting position to form a
cascade interference
optical path, and tapering is conducted on the middle portion of the seven-core optical
fiber section to form a sensing area. According to the invention,
mode matching is improved through the
microsphere cavity, an evanescent field is enhanced through tapering, and high-sensitivity
specific detection of
folic acid is realized in cooperation with the
folic acid binding protein biological functional layer fixed on the surface; the sensor obtains stable linear response to a folic acid
standard solution in the range of 0-50 ng / mL, a clinical serum sample verifies that the detection result of the sensor is highly consistent with that of a
chemiluminescence method, the sensor has good
reusability, and the sensor has the advantages of being easy to prepare in structure, rapid in response, high in sensitivity, capable of being matched with a
complex matrix and the like, and has good application prospects. The method has huge potential in clinical folic acid quantitative detection.