Abstract: The present invention relates to optical ion sensors, including fluorescence optical ion sensors for use in liquid media in the fields of biology, biotechnology, chemistry, medicine, etc. The present invention provides for optical ion sensors that may be attached to dry hydrophilic or hydrophobic surfaces so as to allow continuous sensing. The optical sensors of the present invention may be sterilized and stored for extended periods of time before use.

Abstract: The present invention provides ratiometric fluorescent pH sensors for non-invasive, continuous monitoring of pH in such applications as fermentation processes. The ratiometric fluorescent pH sensors comprise a fluorescent dye that exhibits a shift in excitation wavelength with a corresponding shift in pH in the local environment of said fluorescent dye. Ratiometric measurements of the emission intensities at dual excitation maxima correlate to pH. Also provided is a fluorescent dye 6-methacryloyl-8-hydroxy-1,3-pyrene disulfonic acid (MA-HPDS). Further provided are systems and methods to non-invasively and continuously monitor pH.