In this work we present a double modified internal gate (MIG) pixel structure, fabricated in a slightly modified 0.35 mum CMOS process, to be effectively used in, e.g. low-level irradiance fluorescent imaging applications. The pixel structure enables a non-destructive readout, which facilitates a constant monitoring of the molecule fluorescence process. The readout is based on signal averaging and up-the-ramp sampling current differential readout, which drastically reduces the amount of noise in the pixel output signal. The modified internal gates enable extremely low dark-current and very low-noise operation.