A low-cost modification package will be developed to enhance the sensitivity of a standard confocal microscope and to upgrade its functionality as a tool for studying biological specimens. Replacing analog detectors with photon counting devices will improve signal-to-noise ratio. Digital detection through a confocal port will enable fluorescence correlation spectroscopy (PCS) to study single-molecule kinetics, diffusion, aggregation, viscosity and dynamics of cellular structures. Preliminary data obtained at moderate light levels show > 100% sensitivity enhancement with a digital detection. A much greater enhancement is expected at very low light levels. The pulse-counting electronics, new data acquisition hardware and firmware will be integrated into a compact microcontroller module with a USB connection to a PC with a Lab VIEW user interface and image analysis software. Separate circuitry to control the galvo mirrors will be devised to improve the control over the scanning process and to immobilize the galvo for the fixed-point measurements. Fixed-point measurement mode is necessary for the FCS, single-molecule spectroscopy and pharmaceutical multi-well screening. A custom-designed sideport with collimation optics will be included in the modification package to enhance the microscope collection efficiency. A low-cost fiberoptic spectrometer will be attached to the sideport to extract single molecule dynamics information from fluorescence signal (fixed-point mode) and to obtain hyperspectral image (scanning mode) of the sample. The proposed improvements are relatively simple, inexpensive and not tied to a specific brand of instrument. To facilitate a future commercialization, a microscope maintenance/modification company that is interested in distribution of the product version of the modification package has been identified
