Figure 1.

Live cell interferometer (LCI). The LCI (a) is a Michelson-type interference microscope that compares the optical thickness of a reference cell to the optical thickness of samples placed in the observation chamber. Suspended in the observation chamber is a mirrored substrate, allowing the LCI to make measurements of optical thickness on transparent cells. The relative position of the microscope objective and observation chamber is controlled by computer and translatable in three-dimensions allowing for rapid, automated image acquisition. Throughout data collection, cells in the observation chamber are maintained in standard cell culture conditions (e.g., pH 7.4, 37°C, 5% CO₂). The LCI is capable of measuring the mass of both adherent and nonadherent cells. Frame (b) shows several nonadherent H929 cells attached to the observation chamber substrate after coating the substrate with Poly-L-Lysine solution, whereas frame (c) shows adherent female Indian Muntjac (9) cells cultured directly on the substrate. The color maps show optical thickness measurements with blue being a low optical thickness relative to background and red being a high optical thickness.