Reflective fiber-optic sensor for on-line nondestructive monitoring of Aspergillus on the surface of cultural paper relics

A reflective fiber-optic sensor was created to realize on-line nondestructive monitoring of the growth process of Aspergillus on the surface of cultural paper relics. The sensor consisted of one tapered input and six output optical fibers. The operating principle of the device was established. The sensitivity of the sensor was checked. Sensors were used to monitor the growth of Aspergillus niger, Aspergillus flavus, and Aspergillus tamarrii on the papers. The morphology of Aspergillus was characterized. The sensor reveals a linear relationship between the output signal of the sensor and the thickness of Aspergillus biofilm with a detection limit of 10 µm.