The Study of Cell Dynamics with a Novel Phase Referenced Low Coherence Interferometer with sub-wavelength and sub-hertz Sensitivity

We report the use of a highly sensitive phase based motion measurement technique to study the correlation of cellular metabolic rate with cellular motions. The technique is based on a modified Michelson interferometer with a composite laser beam of 1550 nm low coherence light and 775 nm CW light. In this system, motional artifacts from vibrations in the interferometer are completely eliminated. We demonstrate that the system is sensitive to motions as small as 3.6 nm and velocities as small as 1 nm/s. Using the system, we show that the cellular motions are strongly dependent on the ambient temperature. We observe that the dependency does not conform to Brownian motion predictions but instead appears to correlate with the optical ambient temperature that the cells have evolved to operate in.