DEVELOPMENT OF NEAR-FIELD OPTIC ATOMIC-FORCE MICROSCOPE FOR BIOLOGICAL-MATERIALS IN AQUEOUS-SOLUTIONS

This paper reports improvements of optical fiber cantilevers and the s canning near-field optical microscopy imaging of biological materials in liquid. In our scanning near-field optical/atomic-force microscope (SNOAM), the scanning of an optical fiber cantilever over the specimen was controlled by dynamic mode AFM to reduce damage to the probe acid soft specimens, The typical resonant frequency of the optical fiber c antilever was 19.5 kHz, while it was 23.0 kHz in air. The Q-factor of the cantilever depended on the vibration amplitude and was typically 2 60-600 in air and 40-240 in water. The relationship between the vibrat ion amplitude and the average sample-probe separation indicated that t he cantilever worked in the non-contact mode in water, while it worked in the cyclic-contact mode in air, Cultured cells in aqueous solution s were visualized by the SNOAM, indicating that the SNOAM is suitable to observe soft specimens.