Microsphere-fiber optic biosensor for yeast vibration measurement

We propose an integrated fiber optic biosensor based on a microsphere lens, consisting of a tapered single-mode optical fiber and a microsphere with a diameter of 5 μ m . The sensor operates based on the photon nanojet phenomenon, where the interaction between the microsphere and the surrounding medium is significantly enhanced when the microsphere surface is illuminated by light emitted from the optical fiber. This phenomenon provides a new approach for the precise detection of biological cell activity. During the experiments, we utilized a Mach-Zehnder interferometer as an edge filter to convert amplitude modulation and frequency modulation signals, thereby effectively improving signal quality. Experimental results demonstrate that the sensor achieves a detection accuracy of 1 nm. Leveraging this high-precision capability, we successfully applied the sensor to measure the respiratory vibrations of yeast cells and were able to detect the characteristic frequency of yeast respiration at varying activity levels. This sensor holds promising potential as a technological tool for biosensing and single-cell research.